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ndiiorio
05-02-2008, 05:21 PM
i ve stated before in another thread i have a check engine light for low maf voltage, but car seems to run fine. occaisonally, when im accelerating heavily the car feels like it cuts out for a second, then its back to normal acceleration, but the check engine light goes off until i get off the gas then it comes back on. the engine was just put all back together. i havent checked the plugs yet but could all of this be related?

BRIAN WALTER
05-02-2008, 07:10 PM
Get a new maf and go from there. I just bought a xr7 with no maf attached to the tube.....ran fine....but would only cut out under WOT under certain loads. A new maf from sccoa member for $20 fixed it

f1rocco
05-02-2008, 07:14 PM
Clean the maf sensor and check your plugs....

If your running rich your oil is taking it on and your bearings next...Maybe 02 sensors as well.............

ndiiorio
05-02-2008, 10:42 PM
changed maf electronics and the same, o2 sensors brand new, i found a vacuum leak and now thats fixed, but still the same. i havent checked my plugs yet.

Thundersc90
05-03-2008, 01:46 AM
hi i have exactly the same problem and i lost 4lbs of boost.

Scott Long
05-03-2008, 09:32 AM
Change the plugs and wires, it's getting spark blow out under boost. Either the plugs are bad, or the wires are bad.

Get some autolite plugs and I've personally had good experience with the $30 set of plug wires from Auto Zone. They have a lifetime warranty so you can replace them for free every other year too. :D

cbt
05-03-2008, 12:16 PM
im with scott change out the plug wires, Borg Warner Select / super mags CH8651 is a nice set of wires ,with some autolites, all-ways run good wires and plugs, if you just got it back together check/make sure there's, no air leaks

Scott Long
05-03-2008, 01:13 PM
Plugs and wires are essential on a supercharged motor. On an N/A motor, you can get by longer on old plugs and weak wires than you can with a supercharged motor. When you go into boost you are literally ramming air into the motor, so the engine has to have more fuel and a stronger spark to ignite the mixture. Weak wires that would work fine on an N/A motor can't provide a strong enough current to the plugs. Then again the best wires in the world won't make ~~~~~~ plugs fire any better.

Stay away from any of the Bosch platinum plugs, they suck for forced induction because the electrode is microscopic and sheilded into the insulation of the plug. They don't make a very powerful spark (contrary to what Bosch says in their advertising) the plugs are crap. They lasted me 6 months in my stock SC. Ever since I've ran autolites and have not a bad thing to say about them.

cbt
05-04-2008, 12:07 AM
bucks under boost?

just know that the minute you feel something like that coming on ( the bucking or or missing ) get off the throttle, and try and figure out why, it's not good for the motor any at all....( hg's)

dwayne
05-04-2008, 02:11 AM
just a thought,have you changed the fuel filter latley.

ndiiorio
05-04-2008, 02:29 AM
changed the plugs, filter is new, and I just replaced hg and a whole lot of other stuff... this just started happening. im also getting a rough idle sometimes. I haven't found a vac leak and the factory gauge is reading 19-20 at idle. im going to get some more wires but its gonna be a while Because there is nothing local... I was convinced it was the plugs, I don't know, im stumped.

dwayne
05-04-2008, 03:23 AM
my 89 idles at 20,but runs great at wot 15 psi of boost,no problem their.it did however start a bucking like it was running out of fuel,got to looking the SCbelt was cutting through a wireing harness,left of water pump 2 wires tuching taped them upand zip tiedthe harness away from SC belt.fixed the problem,might be worth looking into.

David Neibert
05-04-2008, 10:06 AM
changed the plugs, filter is new, and I just replaced hg and a whole lot of other stuff... this just started happening. im also getting a rough idle sometimes. I haven't found a vac leak and the factory gauge is reading 19-20 at idle. im going to get some more wires but its gonna be a while Because there is nothing local... I was convinced it was the plugs, I don't know, im stumped.

If your using stock wires, older ones can be damaged just by changing the plugs. Install a new set of wires (suggest Taylor Spiro Core) before doing anything else.

David

RoccoRock05
05-05-2008, 11:27 AM
if you took off the lower intake manifold, thats probably the problem. i had similar problems under boost. just a thought.

fturner
05-05-2008, 11:45 AM
Did you by any chance get a chip done for that setup? You've got a 76mm MAF and hopefully the right sized sampling tube for those 38# injectors, and a 85mm TB, and an s-ported blower with 10% OD on it.

I can see where the MAF low voltage is coming from so a chip will need to be done to get rid of that error. The hesitation or what ever your feeling is probably the car going way lean momentarily as you dramatically increased the amount of air thats allowed to go in at once and nothing in place to compensate injector wise, which would need to be done by a chip. Also without a chip, your load calculations will be skewed down and that number is used to calculate fuel and spark.

Frit

Tech_Greek
05-05-2008, 12:39 PM
my 89 idles at 20,but runs great at wot 15 psi of boost,no problem their.it did however start a bucking like it was running out of fuel,got to looking the SCbelt was cutting through a wireing harness,left of water pump 2 wires tuching taped them upand zip tiedthe harness away from SC belt.fixed the problem,might be worth looking into.

Same issue I had, it was the DIS Harness at that...but mine was rubbing the pulley instead...

ndiiorio
05-05-2008, 02:04 PM
wires have been ordered as we speak, even if thats not the case its worthwhile for me. i was thinking too that the car is running lean and that was the problem... chip is also on its way. the wires are all clear of the belts and none appear to be damaged.
the sampling tube is correct... 38lb. inj + 76mm = orange

kenewagner
05-05-2008, 02:49 PM
Change the plugs and wires. Scott and David on right. Most of the time its the basic problem that needs addressing. My car wouldnt even start a week ago. I changed the plugs, started right up and idles beautifully. Of course I have some of David's go fast red plug wires on it too;)

Ken

ndiiorio
05-05-2008, 08:45 PM
thats exactly what i have on its way... should have them by the end ofo the week, i will let you know what happens.

ndiiorio
05-20-2008, 12:28 PM
alright heres the update... new plugs and wires and got a chip from dave. well the bad news is the problem is now worse. and addition to the 66 code i also have 87 and 95 now. this all definately seems some sort of fuel delivery problem. i havent checked the fuel pressure at the rail yet as im trying to get a hold of a gauge. the 87 and 95 have to do with the fuel pump circuit? if the car is getting fuel then im assuming everything is getting turned on, could there just be a lack of voltage or ground issue? i need some big help, this is the last thing i need to get everything running right. thanks everyone

old_coot
05-20-2008, 01:09 PM
have you replaced the throttle position sensor---Anthony Arnold's motor looked like it wanted to jump out of the car on the dyno until we changed it and then it was full on..............Dan

David Neibert
05-20-2008, 01:16 PM
Double check the plug wires to make sure they are installed as shown on this diagram. Some of the repair manuals have the coil pack numbers shown wrong.

http://members.tccoa.com/dneibert/PlugandWireLayout.jpg

David

nickleman60
05-20-2008, 02:38 PM
If your using stock wires, older ones can be damaged just by changing the plugs. Install a new set of wires (suggest Taylor Spiro Core) before doing anything else.

David

David, where can you get those wires and how much are they? I found a model # , 74X69 , but that's it.

ndiiorio
05-20-2008, 03:17 PM
I rechecked the plug wires and they are correct.

David Neibert
05-20-2008, 04:25 PM
David, where can you get those wires and how much are they? I found a model # , 74X69 , but that's it.

These are the ones I'm using. They also make them in blue, but I don't have the part number handy.


http://store.summitracing.com/partdetail.asp?autofilter=1&part=TAY%2D74269&N=700+0&autoview=sku

David

RoccoRock05
05-20-2008, 06:19 PM
if you took the lower intake manifold off at all, recheck to torque on the bolts. I wrenched on them hard from the inside out only twice. I should have done it a few more times. The car would idle a little rough, but it would run. whenever it went above 5 lbs of boost it would sound like it was missing, like a fuel or ignition problem. once i found the leak, i retorqued the bolts, several times, seated the injectors a little bit further then they were and bingo, problem solved. ran like a champ till i blew the HG's :D

ndiiorio
05-20-2008, 08:51 PM
i got the blue ones...

i will go through and recheck for vacuum leaks again.

now i get a loss of power at any speed with slow acceleration. its like the car is not gettin any fuel. once i take my foot off the accelerator its like it turns back on. what problems would amplify because of a chip? i dont think the chip is causing the problem but it may be amplifying a problem that i had earlier. i just picked up a fuel pressure gauge and i will check that out. i believe it should be in the 40psi range at idle correct? thats why im stuck on the fuel thing, i believe there was an underlying fuel issue now made more noticeable because of the chip and along with the new 87 and 95 codes which point to the fuel circuit it really seems to point in that direction. i havent changed the tps but im not ruling it out. it just seems if it was a bad tps i would have the same problems with or without the chip. any other suggestions?

XR7 Dave
05-20-2008, 09:34 PM
You'll need to verify fuel pressure under load. This means driving with the gauge connected so you can observe pressure when you press on the gas. It should go up and hold steady and not drop off. I see that you have a 255lph fuel pump but it is still possible to have a leak in the tank or something that would cause fuel pressure to be weak. Also, when you have an adjustable regulator you MUST set pressure. 43psi with the vacuum line removed from the regulator. Another way to set pressure is to turn the key on and jumper the fuel pump wires in the diagnostic connector so that the pump runs continually. That makes it easy to set pressure without disconnecting the vacuum line.

ndiiorio
05-20-2008, 11:59 PM
ok... checked for vacuum leaks and I couldn't find any. fuel pressure was low but has now been adjusted and test drove to make sure pressure raised with throttle and maintained. it does drive a little better, but still idles a little rough but not as bad. I still have cel and still have same three codes 66, 87, 95. the other thing I discovered is when maf sensor is disconnected it stops the loss of power when driving, when plugged back in it resumes. what are the four wires at the plug and where do they go. I need to check continuity and if that's ok, im thinking its the maf sensor. this is my second one but I guess it could be bad as well.

ndiiorio
05-21-2008, 01:13 PM
any other thoughts out there?

XR7 Dave
05-21-2008, 02:33 PM
I have tried sending you emails but they are not getting through.

1990XR7SC
05-21-2008, 03:05 PM
ive been keeping an eye on this as well and i suspect the maf. Since you said it gets better with it unplugged vs plugged in. so id say swap it out with a known working one to see if it goes away. if it does then theres your culprate. if not then keep digging. have you thought about the coil pack being bad? since i havent seen it covered. or what bout the crank and cam sensors? new? bad? good? what? But keep digging you will get her right.

ndiiorio
05-21-2008, 05:13 PM
almost every sensor is new, I have a brand new coil pack, this is my second mafs, im thinking it might be the ecc.

don't know what's wrong with my email, pm me?

XR7 Dave
05-21-2008, 06:14 PM
almost every sensor is new, I have a brand new coil pack, this is my second mafs, im thinking it might be the ecc.

don't know what's wrong with my email, pm me?

I didn't realize you were having these issues prior to sending out the chip. Send it back and I will make some changes that may help you out. Don't swap any more parts for now.

ndiiorio
05-21-2008, 09:00 PM
ok it will have to be next week, im on another island working right now.
I read on another post about someone having similar problems and they got a new ecc. I was thinking this is where I was headed.
dave ou responded to one of my previous post when I was trying to use my eec tunerbeen and having an sct chip made by a local shopping and it has similar effects to what is going on now. like the rougher idle. I knew there was something going on wih the fuel I wish I could have got a gauge to read the pressure sooner to make sure, but now that is taken care of in my head all that is left is either the mafs or the ecc. I definatel don't want to mask something with a chip as I still have more upgrades to do in the future. I really want to make sure that everything is working properly.

my problem started out as very infrequent and now has become an almost always scenario with or without the chip.

XR7 Dave
05-21-2008, 10:32 PM
Oh, well I forget some of the things, too many situations going on to keep them all straight in my head. :rolleyes: An 89-90 EEC should be easy to come by used and relatively cheap. It doesn't have to be a specific EEC as long as it is from an 89-90. EEC problems are not common but they do happen.

ndiiorio
06-04-2008, 12:55 AM
put in a new eec and everything is working good. that has probably been my problem for a long time. thanks for the help.

sinhumane
08-15-2008, 11:33 AM
i see noone suggested an alternator as the culprit? i just replaced mine.. it remedied my spark blowout/ chugging, bucking, whatever....

35thauto
08-15-2008, 12:22 PM
i see noone suggested an alternator as the culprit? i just replaced mine.. it remedied my spark blowout/ chugging, bucking, whatever....

We also sealed your SC top & IC that were bare when we got it apart & your Alt. was pulsing 15 volts before replacement.