TPS "Code 23" Cause a No Start???

OK, for starters, I have No CE light at all and have had no starting problems either, until today. The car is a 90 SC 5spd w/100K mi. on it.

I will reveal that I have recently installed a 75MM Tbody and have had idle issues...I think the TPS voltage is too high @ idle...

OK, this is what it did to me today: I started it up "no issues" and went to an appointment. Was there for about an Hour. Came out to leave and the car just cranked over & over & over...It would not even stumbe a lil bit, no hint of a start happening at all. I am stunned at this point, since the car has NEVER done anything like this before. I disconnect and reconnect several sensor connections and try to start and keep getting the same result...The fuel pump is doing its thing, I mean the car has been running STRONG as ever...

OK...So I remember I have my Code Scanner in the car with me. I run a Scan Test and get the "CODE 23" for the TPS and nothing else. I just says that it is out of Range...Well I figured it was anyway...I thought well I will clear the code and see what happens. So it clears succesfully and I try to start. Well the car Touched off in a heartbeat, and never even acted like it was loaded up with fuel or anything. I get home and Shut it down and am able to start it back up time and time again with no problems.

Well I talked to Jason Marsh about it and we are thinking that the TPS can not cause this to happen. And at the same time you can't ignore the fact that clearing that code, the only code, and getting a normal start afterwards.

Now, on my way to work several hours later I got the exact same scenario. I cleared the TPS Code and it fired right up. This time I thought I would disonnect my IAC and see what happens, cuz the idle does not spazz with the IAC unplugged. Got to work and shut it down and was able to restart over and over again...I would add that the car runs GREAT once she is runnin'...

OK...Now I went out to the car after being at work for 3 hours "W/IAC Unpluuged". The car starts normal now...I guess I need to get the TPS voltage where it should be. The Tbody I put on there has a mechanical adjustment where the TPS attaches...Anyone have any exp. with these?

I am thinking maybe the IAC disconnected kept the TPS voltage within' limits, therefore it never popped the "Code 23" ...

I am still confused as to how either of these components keeps the car from firing...

Thanks for your support in advance...

Brad

TTT

ttt

Short answer: no. You can run and drive around (and race) all day with no TPS whatsoever.

Long answer: Well, it starts with me going through 6 of them, and I don't have time right now for the details

Try slotting the screw holes to make it (slightly) more adjustible. That can help one that would otherwise be junk.

IAC?

Someone please explain what IAC is and what it does. Can someone show me or tell me where its located?!!

thanks,

YES

If your tps fails your engine Will NOT start, or if it's out of range.
I had that class last semester, I can't explain it out of my head, so I 'll try to find the paper work that I have i will post it so you can read it.

The IAC is call the Idle Air Control. Basically, it controls your idle by controlling the amount of air entering the engine when no throttle is applied.

It is located on the throttle body.

Here's a picture of its location.

Dale

Re: YES

Superloop said:

If your tps fails your engine Will NOT start, or if it's out of range.
I had that class last semester, I can't explain it out of my head, so I 'll try to find the paper work that I have i will post it so you can read it.

Click to expand...

That's not correct.

You don't even need a TPS to operate/run the car. The EEC is able to estimate the throttle position from the other sensors (primarily the MAF). Unplug it and see for yourself.

Pretty much the only sensor that will cause a no start when it fails is the MAF, and even then, you may be able to sustain a rough idle depending on the type of failure. Other electrical parts on the other hand, no guarantees there.

Just as an FYI, I can tell you that you CAN run your car even with the MAF sensor electronics sitting in your garage.

Don't ask me how I know.

Dale

I didn't know,but know I do.
Why do they use TPS if the cars don't need it ?

Can someone show me a pic of the MAF censor and where its located?

OK Class is in!!!!!!!!!

Here's the low down.....


1) The only SENSOR (ONLY SENSOR), that will cause a no start condition is the CRANKSHAFT SENSOR.

This sensor gives injector pulse and without it, will not start.

Anyone that ever had one go bad knows this VERY WELL!!!


2) The TPS is a THROTTLE POSITION SENSOR. It tells the computer where the throttle plate is in relation to air flow. The more accelerator you give the engine, the more TPS voltage goes to the PCM. Normal voltage is .9 volts at idle to 4.9-5.1 at WOT.

With the TPS not plugged in, the engine should start and will immediately give a Check engine light.

When they go bad, you get a bog at part throttle or trying to accelerate. At WOT, the PCM does not use sensors and goes to a seperate WOT program anyway. Full fuel and just adjusts for timing.

If you are getting a no start thing, check to see if the Up-shift light on the tach is on while cranking. It should go off while cranking and engine starts. If while cranking, the up-shift light stays on, Crankshaft sensor is bad. Very common to go bad when oil or anti-freeze leak on it.

MAF will not cause a no-start, rather a very hard start.

IAC is IDLE AIR CONTROL. This bypasses air around the closed throttle plate to allow the engine to idle. Without this, you would have to keep your foot on the gas to keep it running.

Both the IAC and TPS sensors are located on throttle body. A very common mistake is the TPS goes bad due to someone twisting the actual piece inside. I have seen this WAY to many times.


Anyway, if you have any questions, feel free to call me at (973) 277-4294 (New Jersey).


I would be glad to help you in any way with the car.



Don

UPDATE!!!!

Since this problem described earlier started, the same scenario went on for a few more days and had me convinced that I had a foothold on the problem. "Wrong"

Well, I was on my way out of town and the wife needed to stop at the drug store. I pulled up to the store and set my brake and the car dies as though I had turned the key in the off postion. I went to check codes and I got a "14" for the crank sensor. I cleared it and I tried cranking and that is all that it did along with the "UP SHIFT" light...

Replaced Crank sensor as per "XRDaves" quick Cranks sensor thread in the TBSCEC FAQ and it fixed my problem...Thanks for the help Dave, it was nice to know exactly what to expect before I went under the car in 4" of snow...I know, it was kinda crazy/stupid to do it in the snow, but I needed my F*%$EN car...Since my #2 SC is without an engine right now...

So I guess I was possibly clearing the Crank sensor problem all those times...I don't really know for sure how I was able to clear codes and get a good start...Nor how I was able to get a good start with the IAC unplugged, up until my last described scenario...Or if any of it was even related...I should be half way use to this by now I guess...

Cheers

Brad

Sorry Lube...

But regardless of the theory, I've had a bad CAM sensor on 2 different 90 SC's keep the car from starting. No spark = no start.

Agreed....

It is hard to argue theory, when your problem defeats it everytime you go to start the thing. It is so common for the SC to get you on the wrong track in solving a problem. Bottom line is this thing never really showed its face until it popped the "14" code...It never gave that code before...This made more sense for my no start problem. Even after I got a good code to match the problem I was still being told that it could and probably is not the Crank Sensor, and that it would turn out to be the Cam Sensor or DIS module...Well I ordered a few spares anyways...I hit the 100K mark not too long ago on my 90SC so I think I need to pack some parts & tools around in her for awhile...

Thanks for all of the input gents...

Brad