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View Full Version : SC making boost in nuetral...car accelerating on it's own new tranny slipping!!!



superdadsc
08-02-2014, 06:11 PM
My car has demon's and needs help in a big way!!! I got the tranny from Alan at Dirty Dog put in and was so excited to drive a SC that would run properly. Not a chance as there are to many issues and I don't know what to think or how to fix it. I swapped the blower, plenum and DIC onto the 94 auto that just got the new tranny installed. When we went to start the car it was running really rough and figured it was a vacuum leak. The car's cat on the driver side started glowing red hot. Shut it down let it cool and started again. Thinking it had bad gas I put some more in and the cat wasn't hot anymore, red hot that is. Took the car for a drive in the neighborhood and it stumbled and drove poorly but if you gave it 1/2 throttle it ran just fine. At this point I figured I had a vacuum leak and called Mike and drove the car down to his house to check it all out.

Driving to Mikes the tranny started slipping in OD. Great not even 30 miles and it's slipping. Plus when you put it in reverse it feels really strange like it is fighting itself. I get it to Mikes and we replaced tightened the egr plate. We found a vacuum hose that was sounding like a fog horn and the car was still stumbling running like crap. Then we noticed that when we gave the car some gas that the car went out of vacuum and into boost 5 to 7 lbs depending upon the amount of gas you gave it. Weird. How does it show boost in neutral.... clogged exhaust? Bad O2's?

We noticed if it started running poorly, after a few minutes that when you shut the car down it would run better for a bit then you would repeat that process and it would continue. So when I had to come home when it would start to loss power, I would be giving the car gas, boost is climbing and the car would have no power. It would stumble, sound like a truck drive like crap then I would throw it in neutral, restart it and I could accelerate again.

Then something really weird happened. The car would accelerate on it's own. It would rev up to 3.5k I would throw it in neutral and it would climb to 5k and I would shut it off. Then start the car again, car was getting gas like I had my foot on the gas but I had it behind the pedal to stop it from accelerating and the pedal was doing nothing. I wasn't moving but the car would rev and then after a few minutes it felt like someone was trying to floor it but the pedal was doing nothing.

The worst part was the tranny on first glance feels like it has very soft shifts and starts slipping on the highway the minute it go to much gas. Luckily on the way home there was a lot of traffic so I was doing 30 to 50mph on the way home.

To sum it up

Cat on driver side got red hot, got a little better but still hot.
Car makes boost in neutral or park
stumbles and will lose all power after being driven for a few minutes, restart and repeat process to get home.
Accelerates on it's own then it acts like it is getting floored
tranny slips

Two nice SC's and they both won't stop causing me trouble. Now I guess I have to switch everything over to drive the 89. Spent 2600 on a tranny that slips but I am hoping that it is somehow related to these issues but I don't know why OD would slip.

Help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Mike8675309
08-02-2014, 09:19 PM
Massive Vacuum leak for one.
TV cable adjustment for the other.

superdadsc
08-02-2014, 09:56 PM
It is a late model mustang tranny with SC internals so no TV cable. It's electronic.
There are no vacuum leaks but I guess we could have missed one.

How about the car accelerating on it's own.......cruise control malfunction?

Why does the car make 8lbs of boost when you hit the gas pedal in park?

Does a vacuum leak cause the cat to get so hot? Chicken before the egg scenario bad cat causing the O2 to malfunction or a bad O2 causing a lean condition causing the cat to heat up? Why one side and not the other?

What about the O2 sensor as the car seems to drive differently in open and closed loop?

Car ran flawlessly before the tranny swap so what could have happened in a 3 to 4 month period as it sat in my driveway?

superdadsc
08-02-2014, 10:02 PM
Spoke to alan and he stated that the tranny could be different things so we will look into that. If need to I will drive it to his shop when I get it running right.

Monday I will drop the exhaust and see what is there. Probably punch out the cats or see if there is some kind of blockage somewhere.

Frustrated in GA!

Mike Puckett
08-03-2014, 09:25 AM
It seems like my old 35th slipped in O/D after a rebuild and it turned out to be a bad valve body.

1FSTBRD
08-03-2014, 01:54 PM
Sorry to hear, man. You have a bunch of stuff you've done and are feeling good and then wham! It's not running right.

I suppose that it may possibly be a plugged cat, but a glowing cat is indicative of a lean condition--way too much air in the air/ fuel mix.

I know that the transmission goes by what the TPS is sending it......could it be a faulty TPS or maybe the TPS connection had got unplugged? I had a faulty TPS on my Mustang after installing a bigger throttle body, and the car wouldn't shift right and felt like the tranny was slipping. Try to get a voltmeter to see if it's reading properly.

Mike's right on the vacuum leak. Check all connections and hoses, especially something like PCV hoses.

Mike Puckett
08-03-2014, 06:16 PM
I sprayed starting ether all around and nothing really changed no matter which connection I sprayed it on. I think it needs to be smoke tested.

superdadsc
08-04-2014, 11:55 AM
Got the car jacked up and there is only one O2 sensor on the car and it is on the passenger side
There is nothing on the drivers side.

Going to gut the cat and replace the o2

It is a true duel setup so is one o2 on the passenger side adequate?

KMT
08-04-2014, 12:01 PM
Got the car jacked up and there is only one O2 sensor on the car and it is on the passenger side
There is nothing on the drivers side.


Does it throw any codes?

Les Borda
08-04-2014, 12:20 PM
One O2? That seems odd on a 90 should be one in the exhaust manifold on the drivers side and a 3rd one,can't recall where the 3rd one is.

I may have your year wrong but one O2 sensor still seems odd.

Mike8675309
08-04-2014, 02:56 PM
SC strategy requires 2 narrow band o2 sensors. One on each side. The tune can be modified to cause the car to pull o2 signals off of just one of the two, and by default it will stop looking at one of them if it is too crazy (and it sets a MIL).

California SC's may of have 3 sensors, but if they did I've not seen them. I'm not sure where the after cat feedback would go into the stock strategy.

superdadsc
08-04-2014, 03:10 PM
The car is a 94 auto. We had a coder on it. It was throwing a code then counting the beeps we lost track then reset and there were no codes.:confused: The car has a custom exhaust. It is a true duel setup. One o2 on passenger side. The car ran flawlessly with the exhaust setup w/ one o2 before the tranny failed. Then upon restart with new tranny these issues showed up. So nothing was changed but the tranny so something happened when it sat for 3 months.

superdadsc
08-04-2014, 10:46 PM
Well I was wrong as usual. There was anothet o2 on the drivers side, I replaced it tonight, gutted the cats and took of the ic tubes and checked for any blockage. Everything looked fine but when I hooked up the Ic tubed, stock tubes with a DIC, I didnt use ultra blak so this time I did. Before I did the ultra black on the ic tubes I started the car. I had disconnected the cruise on the Tb and when I started the car it idled and then the car accelerated to 4500 rpm and I wasnt even sitting in the car. Then I resealed the tubes and it will sit over night.

What can cause the car to rev so high on its own? What causes the car to show 5 lbs of boost at idle in park with gutted cats? Could a vacuum leak do that?

superdadsc
08-05-2014, 12:24 AM
So I let the car sit for a few hrs. Took the car for a spin thru the neighborhood. Bad idea! The car showed zero vacuum. I took the car out and it accelerated to 50mph on it own w/ my foot hitting the fing brake!!. I didn't even hit the gas pedal!!! ~~~!!

No boost at idle, maybe a few pounds but the car drives itself!

No one has any clue or no one has seen this before.

If by chance you don't like me or my post's for whatever reason if someone has a clue they should respond to help out a fellow member in the future.

I almost crashed the car coming down a hill in a 25 zone as with my foot on the brake hard was still doing over 50 and I had no brakes

202 views and 5 reply's. No one has a clue? I am starting to get really pissed.

I guess it is a vacuum leak!!

SC Freak
08-05-2014, 01:01 AM
I am far from an expert, and far more knowledgeable people than myself have already responded, but I have to respond because I am sensing your frustration and maybe I can help.

My SC would also accelerate on it's own a few years ago. It turns out that my throttle cable had a burr in it that was causing it to stick. Very scary stuff indeed! Nearly messed myself. Lol.

Check the cable. You never know.

Sorry, but my limited experience/knowledge prohibits me from helping with your other issues.

I hope you get it running right.

Best of luck.

1FSTBRD
08-05-2014, 01:21 AM
It's tough to diagnose, because it sounds like you have a few problems that are coinciding with each other.

I don't think that a vacuum leak would give you this sort of problem. You'd have severe idle problems (ie: would idle really high or would stutter and stumble and would stall out). It's possible that you do have a vacuum leak, but i'm not sure if it's the cause here.

Like I mentioned in my post in here before, it sounds like you have a throttle position sensor issue. Since you replaced the plenum, i'm assuming that you had taken the throttle body off or put on a new or different one. If you're using a different throttle body, troubleshoot the TPS first......try putting your old one on (if you've used a different one). If it is a Standard TPS, don't use it....they're crap. I used one and will never use anything else but a CTS/ Ford one.

Test your TPS voltage. If the TPS is shot, it will make your transmission think that your car is accelerating and will make the transmission either shift shouldn't or not shift when it should. It also sounds like your accelerator cable might be binding or sticking somewhere--make sure that the throttle body moves freely and that the cable isn't sticking.

I really think that your problem lies in the TPS and throttle cable. And that you need a tune, because the car is running extremely lean (glowing cats). Again, check all your hoses and connections and make sure nothing is disconnected. At any rate, I would park it until the problems are fixed.

Also, with the boost in neutral, I wonder if the vacuum solenoid (or is it called boost vacuum actuator?) isn't faulty or disconnected somehow. If it's not working or is faulty, it will start building boost or not building boost on it's own. I'm not a big expert on that vacuum solenoid thing, but from what I know, when it's dying or disconnected, it will cause issues with those things. Check to see that it's moving freely and that when you step on the accelerator (hood up, car parked), that you can see it moving.

superdadsc
08-05-2014, 01:21 AM
Thank you for your reply. I have a feeling that the tb is a issue but i keep getting told that it is just a butterfly and have checked it an others have too but my gut tells me something is wrong with it. I am not saying that is the only issue but it is so weird that the car ran fine before sitting for a few months and now it seems like such a mystery

1FSTBRD
08-05-2014, 01:34 AM
Whoa, that was a fast reply!

Yeah, with the TPS, as i'd mentioned, when I put a bigger Accufab throttle body on my Mustang, I couldn't get the stock Ford one off of the stock throttle body, so i'd bought a Standard one from the parts store, and then hooked everything up, and the car wouldn't run right. It would shift weird, or not shift at all, and would stumble, as if there was a transmission or even possibly a compression issue. With fuel injected cars, they're told how much fuel to give the car and when to shift the car.......so i'm wondering if that isn't the cause of your glowing cats, too.

Going on common sense, if the TPS is reading that you're in a higher gear when you're actually not--and flooring it when you're driving normally (because the sensor is faulty) it's going to be sending some heavy duty information to the computer that is telling it that it should be preparing all the other engine things for that sort of driving. I'm wondering if the glowing cats aren't a result of the computer trying to send more fuel to the system, and then the fuel trims are cutting back the fuel big time at the O2 sensors of what they're actually reading, resulting in a super messed up air/ fuel reading. For example, that's what those Ebay chips do--"adds 50 hp!" they're resistors that fool the computer into reading lean, and then people end up with a messed up engine.

The fact that your engine is reading way lean and that it's shifting weird--i'm almost positive that it's a TPS issue.

superdadsc
08-05-2014, 07:06 AM
If the TPS is on the right side of the TB Mike and I switched it out with another and there was no change.

Another clue the DIC gets real hot, within a minute from starting it the top of it gets very hot.

Tim Groth
08-05-2014, 08:54 AM
If the TPS is on the right side of the TB Mike and I switched it out with another and there was no change.

Another clue the DIC gets real hot, within a minute from starting it the top of it gets very hot.

on the backside of the motor where you have the Christmas tree of vac hoses (usually right behind the Supercharger) are any of those hoses loose. One of those is actually for Brake vac and makes me wonder if its not loose.

With the problems you're having it sounds like a vac leak for the car will incerease idle speed to compensate the leaks, thus causing it to drive itself persay.

-Tim

joenintiesc
08-05-2014, 09:13 AM
Start over. Remove everything you installed, inspect, and inspect everything still on the engine now that you have extra room to see it. Check the entire length of vac hoses, not just the ends. Check inside the DIC and everywhere else for rags, paper towels or blockage. Then reinstall everything carefully. ~~~~, but at least you can either find, or thoroughly rule out something. I agree with others about the tps or iac usually being the #1 cause of ghost acceleration. Did you look at the iac at all yet?

Good luck and hopefully the trans issues are directly related to these other issues!

(Lol, really? "P I T A" gets censored?)

Mike Puckett
08-05-2014, 10:20 AM
Stephen, I've got spare TPS sensors if we need to replace it. Since we replaced the IAC I think we can rule it out unless it is being activated incorrectly. Try stating it up and wait until the engine wants to race and pull the IAC connector and see if the rpm drop back down. Something else I wonder about is that when I pulled the MAF sensor plug the engine stalled. It should have kept running.

Mike8675309
08-05-2014, 10:24 AM
What can cause the car to rev so high on its own? What causes the car to show 5 lbs of boost at idle in park with gutted cats? Could a vacuum leak do that?

Vacuum leak will do that. Vacuum holds the bypass valve open. If not held open you will make boost even at idle depending on your blower overdrive. For an engine to run it needs air. For an engine to rev higher that means it has more air. Assuming you are not pressing on the throttle means that you have a leak somewhere between the back of the throttle blades and the back of the intake valve. In other words you have a vacuum leak.

Throttle position sensor is only a problem if it is not behaving linearly or it is hitting max value before throttle is opened all the way. TPS doesn't indicate what gear you are in.

I would stop driving it until you can get it to hold idle in the driveway and while in gear with the parking brake on.

1FSTBRD
08-05-2014, 10:32 AM
If the TPS is on the right side of the TB Mike and I switched it out with another and there was no change.

Another clue the DIC gets real hot, within a minute from starting it the top of it gets very hot.

The idle air control is on the right side of the TB, if you're looking at it from the front of the car. The TPS is on the left side.

If the DIC is getting super hot, that's weird. That may point to that boost solenoid being faulty or sticking, because it's building boost when it shouldn't be.

Others may know more about this--if the TPS is faulty, would it then cause the car to build boost, as well, seeing as that the vehicle's computer would be telling the car that it would be otherwise using the blower at that speed?

At any rate, if you're testing the car, get ready to use the e-brake. I'm just glad that you didn't get in a crash.

1FSTBRD
08-05-2014, 10:38 AM
Vacuum leak will do that. Vacuum holds the bypass valve open. If not held open you will make boost even at idle depending on your blower overdrive. For an engine to run it needs air. For an engine to rev higher that means it has more air. Assuming you are not pressing on the throttle means that you have a leak somewhere between the back of the throttle blades and the back of the intake valve. In other words you have a vacuum leak.

Throttle position sensor is only a problem if it is not behaving linearly or it is hitting max value before throttle is opened all the way. TPS doesn't indicate what gear you are in.

I would stop driving it until you can get it to hold idle in the driveway and while in gear with the parking brake on.

I know that there's a sort of hidden hose/ connector on the bottom side of the air intake tube--could this have been forgotten to have been hooked up? I believe that it goes to the driver's side valve cover. I know that there were a couple of times where I almost forgot to hook that up after I'd removed the intake tube. Sometimes it's the really simple things that cause the most aggravation. I know that from past experience, even sometimes after double checking, i'll miss hooking something up. That's why I triple check everything that could have possibly been disconnected.

superdadsc
08-05-2014, 11:09 AM
The car seems to hold idle a little longer before it revs. Mike when it started to rev I pulled the IAC and nothing changed. It still reved. If I pull the maf sensor off while it is running the car dies.

David Neibert
08-05-2014, 12:00 PM
Sounds like the bypass valve behind the supercharger is stuck in the closed position. If vacuum hose is not connected or vacuum signal is weak the bypass will stay shut. Sometimes the linkage binds against the SC top.

David

Mike8675309
08-05-2014, 12:14 PM
That may point to that boost solenoid being faulty or sticking, because it's building boost when it shouldn't be.
...
Others may know more about this--if the TPS is faulty, would it then cause the car to build boost, as well, seeing as that the vehicle's computer would be telling the car that it would be otherwise using the blower at that speed?


The SC motor uses a butterfly valve that under manifold vacuum is open causing air from the blower outlet to recycle into the blower inlet. This reduces the work of the supercharger when power is not needed decreasing the load the blower puts on the engine crankshaft and increases overall efficiency. If there is a lack of vacuum (i.e. from a leak) then the butterfly valve will close causing the blower output to be bypassed. Depending on how much you overdrive the blower, you could create positive pressure in the manifold at idle. there is no "solenoid".

Airflow into the engine is the single most important limitation to the RPM of the motor. The throttle blades are responsible for controlling the air that enters the engine. Leaks of air into the engine from other parts of the intake tract will cause uncontrolled RPM changes. The TPS sensor is responsible for telling the engine management system how wide the throttle is opened and how fast the throttle is opened to improve fueling. The TPS sensor has very little to no impact on Engine RPM, that is what the throttle blades are for.


I know that there's a sort of hidden hose/ connector on the bottom side of the air intake tube--could this have been forgotten to have been hooked up?

That is the crankcase vent that should be connected to the intake tube in front of the throttle blades. Leaving it disconnected can affect engine idle quality as it is a leak of metered air. But in general it doesn't play enough of a role to cause large increases in Engine RPM as the only air running through that is what is in the engine crankcase, not air from the intake manifold


The car seems to hold idle a little longer before it revs. Mike when it started to rev I pulled the IAC and nothing changed. It still reved. If I pull the maf sensor off while it is running the car dies.

Pulling the IAC should not cause any change other than a CEL light triggered. If you remove the MAF sensor the engine will shut down as it no longer can track the mass of air entering the engine. Our engine strategies require a engine mass input to compute fueling. Without that it becomes very confused and shuts down. It may be able to limp home with a bad MAF if you start the car with the MAF disconnected (but not missing) but it won't run right as it will be guessing about fueling values.

You have a vacuum leak somewhere. You need to approach this problem very methodically, and check literally EVERYTHING. The leak seems pretty large so I would focus on things bolted to the blower and bolted to the intake manifold. That means all plenums (throttle body to plenum, plenum to blower, blower to SC top, SC top to tube, tube to intercooler, intercooler to tube, tube to intake manifold plenum, intake manifold plenum to intake manifold.)

Miller
08-05-2014, 02:39 PM
I had a problem a few years back where my car would all of a sudden go WOT and stick. I couldnt figure it out for a while until I had my friend sit under my hood while i drove :rolleyes::cool: it turned out, that during some sort of work I did, i bent the AC accumulator tank a bit towards the TB. Also, my motor mount was bad, so engine would torque towards the tank, and pin the throttle body up against the ac line keeping it stuck open.

KMT
08-05-2014, 03:25 PM
Take a close look between the engine and trans to be sure no wires etc. got sandwiched/pinched during the install.

Remove the throttle cable from the throttle body to confirm the pedal and cable aren't acting up.

superdadsc
08-05-2014, 08:33 PM
Thanks so much for all the reply's!!! I have some work to do. Hopefully tomorrow I will have time to work on the car!!

Mike Puckett
08-06-2014, 07:59 AM
The bypass valve is moving back and forth with changes in vacuum but I'm now wondering if it is leaking real bad. I'm thinking the supercharger assembly needs to come back off, have everything checked and then be reinstalled.

superdadsc
08-06-2014, 08:16 AM
Also something Mike noticed is the maf sensor is a 89-93 w/ a 55 number and he stated that it should be a 70 number so that needs to be replaced.

Mike8675309
08-06-2014, 09:37 AM
The bypass valve is moving back and forth with changes in vacuum but I'm now wondering if it is leaking real bad. I'm thinking the supercharger assembly needs to come back off, have everything checked and then be reinstalled.

Is the bypass open or closed when he saw this? A rag didn't get sucked into or left in the intake did it?:

What causes the car to show 5 lbs of boost at idle in park with gutted cats?

What do you think is a possible cause for this? I'm not clear that this occurred "on it's own" but either there is a vac leak playing hide and seek or there is a problem with the throttle setup. (Cable binding, linkage binding, throttle plate loose):

Then something really weird happened. The car would accelerate on it's own. It would rev up to 3.5k I would throw it in neutral and it would climb to 5k and I would shut it off. Then start the car again, car was getting gas like I had my foot on the gas but I had it behind the pedal to stop it from accelerating and the pedal was doing nothing. I wasn't moving but the car would rev and then after a few minutes it felt like someone was trying to floor it but the pedal was doing nothing.
What can cause the car to rev so high on its own

And whatever all those other things are, this needs to get resolved before running the car on the street, at least making sure the TV cable is properly adjusted. Problems like those described below just don't go away and can be very expensive if they are ignored.

Driving to Mikes the tranny started slipping in OD. Great not even 30 miles and it's slipping. Plus when you put it in reverse it feels really strange like it is fighting itself.
The worst part was the tranny on first glance feels like it has very soft shifts and starts slipping on the highway the minute it go to much gas. Luckily on the way home there was a lot of traffic so I was doing 30 to 50mph on the way home.

superdadsc
08-06-2014, 11:13 AM
Mike the car isn't being driven. It is sitting in my driveway and today I will get a chance to work on it. The episode that I had was driving in my neighborhood and I drove it down the street and back home. My mechanical skills suck so I am only able to do so much. I will get the blower intake off and see what I can. I appreciate everyone's time and help. I have no car to drive which puts strain on the family. I had my business burn down and two SC's fail in one month. A tranny in one and a motor in the other so it has been tough. The wife is really sick of me and my cars and at this point I don't blame her. I wasn't so concerned with the low mileage 89 as I was going to put her in the garage and let her sit and DD the 94. You have mentioned the tv cable but on this tranny it is electronic so no tv cable.

S_Mazza
08-06-2014, 12:33 PM
Smoke testing is the best way to find intake tract leaks. If you don't want to, or can't, find a mechanic to do it, you can make your own cheaply.

http://forums.corral.net/forums/13963633-post39.html

https://www.youtube.com/watch?feature=player_embedded&v=FFlyAqiYMro

1FSTBRD
08-06-2014, 12:47 PM
I have no car to drive which puts strain on the family. I had my business burn down and two SC's fail in one month. A tranny in one and a motor in the other so it has been tough. The wife is really sick of me and my cars and at this point I don't blame her. I wasn't so concerned with the low mileage 89 as I was going to put her in the garage and let her sit and DD the 94. You have mentioned the tv cable but on this tranny it is electronic so no tv cable.

Sorry to hear. Hopefully the money that you'd got from the stuff that i'd bought off you had helped a little bit.

In the case of the problems you're having on this SC, I think it's just minor voodoo in the system....a small thing that's creating a big problem.

superdadsc
08-06-2014, 02:52 PM
I agree!! Small issue big problem!! 1FSTBRD did you get everything on the car? How does it feel?:D

superdadsc
08-06-2014, 08:35 PM
Well hopefully I have found the problem but I won't know until tomorrow. I took the blower off and check all the vacuum lines and everything looked normal. Checked out the blower and the plenum and noticed oil on the bottom of the blower where the plenum attaches. The whole line was oily. Took the plenum off the blower and you could see how on the plenum and blower where it attaches the horizontal connection had a oil on it and was pretty big. The plenum and blower had no sealant on it so I lightly sanded it down and made it smooth and resealed the blower and plenum. So I am hoping that it was the problem. I will know for sure tomorrow but I won't be able to do any work on it till 9pm.

Do you think this could cause all my problems?

Mike8675309
08-07-2014, 09:23 AM
Do you think this could cause all my problems?

Slipping transmission? No, but I guess I'm not sure. Make sure your check engine light is working and make sure it isn't lit. with the electronic trans it can set a CEL as well.

Weird Boost and high idle problems? Yes. Those are machined surfaces on both the Plenum, and the intake manifold. What did you sand them with, and what sealant did you use? That usually has a gasket though a high quality RTV should work.

elanoresc
08-07-2014, 10:25 AM
Not saying this is you problem but my trans went out and started by slipping then went to weak 2nd gear then first gear was not fully engaging. I would say if your gear is not fully engaging that would cause boost in nuetral it could think its in 4th and just not fully engaging just a little food for thought.

superdadsc
08-07-2014, 11:18 AM
Mike I used some sandpaper from and old car painting project so it was a light grit. Just enough to get that burnt oil off and I used Black ultra on the plenum and blower.

David Neibert
08-07-2014, 11:36 AM
Where did the oil come from ? It's normal to get some oil into the supercharger inlet plenum from the PCV valve hose, but adding an oil separator will address that problem.

The plenum not being sealed would cause a vacuum leak, but I've never seen a vacuum leak cause the car to accelerate as much as you were describing. Normally a big vacuum leak would make it nearly impossible to keep the car running at an idle and require constant throttle input, but would feel pretty good under acceleration. Throttle hanging up is not something that makes any sense. I would check for a binding throttle cable or cruise control cable.

David

Mike8675309
08-07-2014, 01:46 PM
The plenum not being sealed would cause a vacuum leak, but I've never seen a vacuum leak cause the car to accelerate as much as you were describing.


I agree that this might not be the full solution, but that was the location I was figuring there was a leak as it is easy to not get that tightened down flat because of the use of only 3 bolts and the offset weight that has. I believe that for sure that leak is responsible for the random signs of boost with only light or no throttle. My guess is there could be other leaks, in particular at the SC top, or the lower intercooler line to intercooler connection.

shoalcracker
08-07-2014, 04:30 PM
I had my engine smoked about a mth ago.

Discovered 3 leaks including CA Plenum.

Car idle was choppy and boost was a bust.

Interesting side effect.

Car on occasion would go done the street at 25 mph.

My foot wasn't on the gas.

This is a 5 speed.

My uneducated guess was the computer continued to hunt for intact air consistency and kept trying to correct.

Hence the drive on the fly moments.

Paul

1FSTBRD
08-08-2014, 10:13 AM
I agree!! Small issue big problem!! 1FSTBRD did you get everything on the car? How does it feel?:D

I've put the DIC on and the IC tubes seem like they're way cooler, just by the fact that I can leave my hand on them after the car is at full operating temps. Definitely feels like the car pulls harder in the upper RPM's! Haven't put the supercharger on, nor the MAF/ TB, because i'm probably going to do that next year when I buy 36 lb injectors and port/ polish the lower manifold while I have things apart.

superdadsc
08-08-2014, 12:43 PM
Got everything back on except the SC belt. But I started the car and the symptoms are the same. I will get the belt on tonight with help from a friend as last time we needed to rotate the pulley to get it on. I have a feeling nothing has changed. Mike has a tps sensor that he will be bringing on sat. I don't get it.

S_Mazza
08-08-2014, 01:15 PM
Got everything back on except the SC belt. But I started the car and the symptoms are the same. I will get the belt on tonight with help from a friend as last time we needed to rotate the pulley to get it on. I have a feeling nothing has changed. Mike has a tps sensor that he will be bringing on sat. I don't get it.

Obviously, as Mike said, the engine runs on air and fuel, not on magic. So the engine is getting air from somewhere. Either it's getting past the throttle plate, past the IAC, or sneaking in from one of the manifold or hose connections.

You said you checked the vacuum lines? Did you actually try the smoke test? I think that would be a productive use of your time.

You said you "pulled the IAC". I assume you mean that you unplugged it? If so, I wouldn't expect that to make a change. The car is already getting more air than it needs. The IAC probably is pegged at minimum already because the car knows it should do everything it can to stop the excess air.

Did you physically remove the IAC and check it for a torn bellows?

Did you check the throttle body and make sure the blade is closing properly, not bent?

There are other things to check in the future, and I suspect that one or more of them may need to be fine tuned before the car runs perfect, but the items above are the most basic and must be addressed before moving on.

superdadsc
08-08-2014, 01:47 PM
IAC was checked and swapped out with another and there was no change. Check TB and everything is in order. Car was smoke tested and there was no leaks. Cruise cable has been disconnected.

S_Mazza
08-08-2014, 01:51 PM
IAC was checked and swapped out with another and there was no change. Check TB and everything is in order. Car was smoke tested and there was no leaks. Cruise cable has been disconnected.

Ok, thanks for clarifying.

This is a 1994, rght? If so, here's another thought - the brake booster. Maybe try disconnecting the brake booster vacuum hose and plugging it, then see what it does.

superdadsc
08-08-2014, 02:27 PM
Thanks I will give that a shot!!

joenintiesc
08-08-2014, 02:50 PM
You thoroughly checked the IC tubes for cracks/holes? How about the intake manifold?

superdadsc
08-08-2014, 03:19 PM
Haven't removed and reinstalled manifold. The ic tubes were removed and resealed with ultra black rtv. If nothing changes i will have to get the silver car running. I just didnt want to put miles on it and it looks like it needs a new fuel pump. More money and i am still not out of hot water financially yet. Lots of stress around here! !

elanoresc
08-08-2014, 03:59 PM
I have a stock fuel pump and assembly almost new only a trip from Michigan to Kentucky and back way under 1000 miles. $30 plus shipping

Mike8675309
08-08-2014, 04:42 PM
Bummer... Perhaps the car is possessed? I have heard that goes around with these SC's from time to time.

1FSTBRD
08-08-2014, 05:39 PM
I don't know what else there is to advise. With the smoke test and the re-checking of hoses, lines, connections, etc, it almost seems like the ECU is damaged......is it a possibility that a couple of wires had got shorted out and possibly damaged the ECU? There's so many issues here that seem to go beyond any rational explanation anymore.

S_Mazza
08-08-2014, 08:32 PM
I don't know what else there is to advise. With the smoke test and the re-checking of hoses, lines, connections, etc, it almost seems like the ECU is damaged......is it a possibility that a couple of wires had got shorted out and possibly damaged the ECU? There's so many issues here that seem to go beyond any rational explanation anymore.

Even a fried ECU can't make the car rev up without air. And it can't open the throttle by itself, especially if the cruise control is disconnected.

Another thought of a vacuum leak possibility: heater control vacuum hoses (if the 1994 still has those).

superdadsc
08-08-2014, 09:16 PM
Will check the heater hose. Could something have been damaged when the tranny was installed? Pulled the brake vacuum line and there was no change. When I sprayed the maf looking for leaks it ran better but would still rev on it own regardless. Still running the same!!

SC Freak
08-08-2014, 11:48 PM
have you checked the throttle cable?

superdadsc
08-09-2014, 07:04 PM
Problem solved! !!! Mike can over to my house today and we checked things out looking for a way to get it running right. No luck and I had a stock TB from a old 89 and we decided to swap it out and the problem was solved. Car ran they way it should. Looks like i need a new maf sensor and the tranny shifts fine but on the highway if you kick it down it feels like OD is slipping but I guess there is no OD the way alan set it up but that can be solved in the future. I have wheels and can get to all my lessons without making my schedule around sharing my wifes car. She is happy!!!!!

A big thanks to Mike Puckett for his help and his friendship!!!

mywhite89
08-09-2014, 07:32 PM
Problem solved! !!! Mike can over to my house today and we checked things out looking for a way to get it running right. No luck and I had a stock TB from a old 89 and we decided to swap it out and the problem was solved. Car ran they way it should. Looks like i need a new maf sensor and the tranny shifts fine but on the highway if you kick it down it feels like OD is slipping but I guess there is no OD the way alan set it up but that can be solved in the future. I have wheels and can get to all my lessons without making my schedule around sharing my wifes car. She is happy!!!!!

A big thanks to Mike Puckett for his help and his friendship!!!

So was the problem the tps, or was the throttle blade sticking open?

Mike8675309
08-09-2014, 08:22 PM
Slipping in Overdrive during high acceleration is the standard way that SC Automatic Transmissions work. The over drive band is not large enough to deal with the power of the engine at that rpm. This is one of the reasons why it is common for SC owners to lock out overdrive either through programming or through a third party valve body that supports an overdrive lock out switch.

It is important that you do not do a floored run into overdrive. That will essentially just kill overdrive quickly.

superdadsc
08-09-2014, 10:14 PM
Slipping occurs at part throttle, quarter throttle or less at low rpm
The tps worked fine but was leaking but didn't show when sprayed.

Mike8675309
08-09-2014, 10:30 PM
Slipping occurs at part throttle, quarter throttle or less at low rpm


For sure contact the person that you go the transmission from. Seems that is an issue within that transmission.

S_Mazza
08-10-2014, 12:02 AM
Excellent! I am glad it's working for you.

Now, what makes you say you need a new MAF? Just the mismatch you noted before between the stock size and what you have now?

Mike Puckett
08-10-2014, 12:48 AM
The TPS sensor doesn't mount directly to the throttle body. There a round spacer about 1/2" thick. It resembles the coupler inside the supercharger. It's slotted to allow adjustment of the TPS voltage. It was mounted without any sealer and the the TPS sensor was screwed down to it. The whole thing leaked big time. Now the engine racing on its own makes sense. It acted just like opening up the throttle and that's where the leak was. Also, the crossover hose wasn't snug on the air inlet tube fitting so I hose clamped it. I ended up putting RTV on just about every connection chasing this thing around. Finally, something a former German colleague from work told me came to mind, " Sometimes you just have to start replacing parts till you find it". Fortunately, we made the right guess and hit it right off the bat. The battery needs to be disconnected overnight to clear the codes so we can check them again. The check engine light is still coming on and there are so many codes in the EEC I can't tell which one is triggering the CEL.

KMT
08-10-2014, 01:26 AM
The check engine light is still coming on and there are so many codes in the EEC I can't tell which one is triggering the CEL.

Always focus on the first code first. Some may be responsible for others. Keep eliminating codes until the list clears. You may get lucky and have the list clear sooner than later.

As for the TPS, isn't there supposed to be a rib type rubber o-ring/gasket involved that sits on the shaft bushing where it goes into the TB?

David Neibert
08-10-2014, 11:13 AM
Slipping occurs at part throttle, quarter throttle or less at low rpm
The tps worked fine but was leaking but didn't show when sprayed.

Are you sure you don't have a non-locking converter ?

David

shoalcracker
08-10-2014, 11:44 AM
[QUOTE=Mike Puckett;1072224]The TPS sensor doesn't mount directly to the throttle body. There a round spacer about 1/2" thick. It resembles the coupler inside the supercharger. It's slotted to allow adjustment of the TPS voltage. It was mounted without any sealer and the the TPS sensor was screwed down to it. The whole thing leaked big time. Now the engine racing on its own makes sense. It acted just like opening up the throttle and that's where the leak was.

Mike

Pretty sure your referring to the PP Throttle Body.

I just reworked the one I have here.

The wheel that the TPS mounts to is free floating for finite voltage adjustment.

If you look inside the centre of the ring you should see a black bushing that surrounds the shaft. They are just press fit in and I know in my case it would fall out if the TB was tilted. (ie loose enough to leak)

You should have bushings at both ends and O Rings on the shaft at each end internally.

If in fact the bushing is present, you can pop it out and RTV it back in. You should find it eliminates the bulk of your problem.

Of course if this is an issue you are best to pull the shaft out and redo the spring side as well.

Paul

superdadsc
08-10-2014, 01:13 PM
The tranny seems to be working better, Around town it is great, It works a little funky on the highway if you are cruising and want the tranny to downshift it will rev and take it's time getting into gear. All and all I am very pleased.

The MAF sensor is a number 50 and the 94 should be a 70, Also the cover has a slight crack in it so I will replace it when I catch up on my bills. The car wants to stall at lights sometimes and stumbles a little but once the car gets some gas she runs great. I know I have a exhaust leak as I gutted my cats and put them back on and they are not welded as they have a sleeve with clamps on it.

David I am not sure what the convertor is but it was built by Alan, I think when money is available I will get a better convertor from him. drive to his shop so he can go thru everything.

Mike Puckett
08-10-2014, 03:36 PM
It chirped and barked the tires a few times when shifting going up to Canton, so that part's working.
Paul, I don't remember seeing that bushing inside but it could be there. I was thinking that RTVing the heck out of it should seal it up. There was no sealer, o'ring, or gasket on it. The sensor itself was good. I put a voltmeter on it and the voltage changed smoothly with no jumps or 'noise'.

shoalcracker
08-10-2014, 06:57 PM
Paul, I don't remember seeing that bushing inside but it could be there. I was thinking that RTVing the heck out of it should seal it up. There was no sealer, o'ring, or gasket on it. The sensor itself was good. I put a voltmeter on it and the voltage changed smoothly with no jumps or 'noise'.

Mike if you can't see a solid black around the TB shaft it's fallen out.

It would be huffing air.

Paul

1FSTBRD
08-12-2014, 11:32 PM
Problem solved! !!! Mike can over to my house today and we checked things out looking for a way to get it running right. No luck and I had a stock TB from a old 89 and we decided to swap it out and the problem was solved. Car ran they way it should. Looks like i need a new maf sensor and the tranny shifts fine but on the highway if you kick it down it feels like OD is slipping but I guess there is no OD the way alan set it up but that can be solved in the future. I have wheels and can get to all my lessons without making my schedule around sharing my wifes car. She is happy!!!!!

A big thanks to Mike Puckett for his help and his friendship!!!

That's great--glad to hear!