I'm in dire need of help. I've done everything I can possibly think of to make this car idle and it has never helped. I've set the TPS to .540 volts, adjusted the IAC to 1 1/8" like my manual says, although I haven't cleaned out the passage way. The fuel pump is about 6 months old and I hear it prime every time I turn the key over, and I just finished replacing the injectors. EGR valve and FPR are a few months old and from what I can see, there are no vacuum leaks. Distributor, cap and rotor are about a year old, and plugs and wires have been on for a day. O2 sensor is new as well. I haven't had a way to check the fuel pressure, because I don't have a guage but I have no reason to believe it's not ok because of the new injectors, FPR and pump. MAF sensor is also no more than a year old. I've been battling this problem for a little over a year, ever since I bought the car. No codes are being thrown either. Thank you for any and all help.

 

Forgot to mention that it only idles if I have my foot on the pedal and as soon as I let off it dies. It doesn't eventually idle or anything. No matter what I do, it just dies. Now I can't even try anything because either my starter went bad, or the wires to the starter need to be replaced. Either way, the only way I got home (luckily I was in the neighborhood) was by pushing the car and popping the clutch and just made sure I stayed on the accelerator.

 

I had a similar problem with my S10 and it turned out to be the computer itself.

 

Well that was my next thing to try. I know I shouldn't have just thrown money at it with all these parts, but all the parts seemed like they had something to do with it.

Are the reman computers from Advanced Auto Parts fine to use?

 

I do all the wrenching on my Iroc, but for the daily driver, it's to the professionals!!!!!!!

........I have no advice or knowledge as to what's good and what isn't with regards to the computer itself.

 

have you tried adjusting the idle screw?if you dont have to hold it down much this may help jimmy

 

This is my DD because I'm only 17 so I can't afford another car. If I didn't love this car so much, I would have rid myself of this burden a long time ago. It's getting hard to keep up with it. And yes, I have adjusted the idle screw. I only adjusted it until my TPS read .54 volts though.

 

try adjusting the idle screw in until it does idle then readjust the tps to .54,jimmy

 

that maf allways goes bad,u replaced it before the computer should be the last thing u change,go get ur maf sensor tested,mine went bad after 8 months

 

Well I don't believe its the MAF because it didn't help the first time I replaced it. I'm pretty sure it's under warranty so I'll just go get another one. Thanks.

 

See if you can get it scanned and see what the IAC counts are. Should be around 20, hot at idle. They start at 140 or so then drop as the engine warms up.

 

My car behaved in a similar manner when the IAC valve went bad, combined with throttle body blades that were improperly adjusted (minimum air).

There is a good write-up here on this site on how to properly set idle (minimum air) and the TPS voltage. Look in the "Technical Articles" Section under "IAC and TPS Adjustment".

Once your minimum air is set correctly, you will be in a better position to determine if there are other problems, such as a bad/stuck IAC valve.

 

ohm test your injectors, they should be within 5 tenths of one another.

 

Thanks for all the replies guys. I'm going to see what I can do about scanning it and finding out what the IAC counts are. The injectors were just serviced and flowmatched so there should be no reason for them not too be good. And even if I ohmed them and they were spot on with each other, they could still be bad. Minimum idle is set properly and everything. I might have to clean out the passage to the IAC because last time I took it out it wasn't at the 1 1/8" I had it set at. I've read that it can damage the valve if the pintle is too long and forced into place. I'm beginning to think it could be the computer itself, though, because the SES light flashed extremely fast and the idle was surging between 3500-4500 before I shut it down.

 

I had a similar problem. Found out it was a broken computer chip. Mine did run and idle though.

 

another vote for adjusting idle screw then re-adj. TPS

 

The IAC Valve moves in and out to meter the air, so it is normal for it not to be in the same position as when you installed it.

Were you always getting an fast flashing SES light when this problem was occuring?

 

Don't make a mountain out of a moehill. Try this first. Cost = nothing.
immo

 

There is a way to make sure the IAC is all the way out. Jumper aldl pins a and b, turn key on, wait 1 min, then unplug the electrical connection of the IAC. This will leave it in the extended position (0 counts). Then remove IAC and set to 1 1/8".

 

Well it seems like everyone thinks that I need to reset the idle speed and then adjust the TPS. I might as well do this seeing as it can't hurt anything and may very well help. Thanks.

 

I adjusted the idle screw and then re-adjusted the tps and it still hasn't helped. I've been working on this problem for too long so I think I'm just taking to a reputable shop. Thanks for all your help guys. But if you think of anything else, please let me know.

 

And I forgot to mention that it is now throwing a code 32 which is and EGR code. I have a new valve, could the solenoid be bad?

 

have you checked the fuel pressure yet?
This past weekend,I replaced the fuel pump in my 91 v6 car(same fuel pump as a tpi) When the key was turned on,the pump would prime just fine,but when started it would struggle just to idle and if I tried to rev it up at all,would bog down and stall out.I hooked up my fuel pressure gauge,and found it had 12 lbs. of pressure instead of 40.5-47 lbs. that it should have.
new fuel pump in and all is well.Car now runs great!
If you were closer to me,I would bring my gauge and check it for ya.
I got the gauge at autozone for $40.
Might be something worth looking into for you.

 

Well my dad is bringing home a fuel guage tomorrow so I'll find out. I'm kind of hoping its that, but I really don't feel like replacing the fuel pump. PITA.

 

Total PITA!!!!
I don't know why gm made these cars like this.Totally dumb setup as far as I'm concerned.

 

I know that my dad and a friend changed mine for me in just a few hours when I was at work one night, but they did it by cutting a hole in the floor above the tank. I know there's some dispute about that, but they welded it back in.

 

did you replace the egr valve? if its stuck open it wont idle,later jimmy

 

Yes, I did.

 

With your foot on the pedal, are you able to get the engine to run smoothly at low RPM, say 1000prm or less? Does it run OK except at idle?

 

It seems to run smooth at any RPM if I have my foot on the pedal. And it seems to have plenty of power when I'm driving it, but as soon as I push in the clutch it'll just fall on its face.

 

I think I found a problem..
I got a fuel pressure guage and when I was testing it I noticed that it would shoot up to 50psi, drop to under 40 in no time at all, and then just keep going and finally stop at around 15. Any ideas?


Well I tried the fuel pressure at idle and it was at 41 and with the vacuum to the FPR it was at 49ish.

 

Having fuel pressure slowly bleed off after the engine is stopped is pretty normal. Is it dropping to 15 when the engine is running or after shutdown?

50 psi is on the high side for fuel pressure, do you have an adjustable fuel pressure regulator or is it stock?

The fuel pressure should go up after the vaccum line is disconnected, and go back down after the line is connected, is that what you were trying to say?

Having said all that, if you are able to get the engine to run smoothly at a low RPM with your foot on the thottle, then I wonder if minimum air is really set properly. What procedure did you use to set minumum air? Did you follow the procedure on this web site?

Basically, first you make sure the idle air valve is fully closed by jumpering ALDL A&B with key on, engine not running. Wait 30 seconds then unplug the IAC connector at the throttle body. Remove the jumper. Start the engine then adjust the throttle blades so the engine is idling at 450 RPM, or higher as neccesary to keep the engine alive. then reset the TPS voltage to 0.54V and reconnect IAC.

A sticking IAC valve combined with minimum air set too low can cause the exact behavior you are describing. I have an LB9 with a T5 and have had this happen more than once. I had minimum air set low intentionally, but that is another story.

How did you set minimum air?

 

Well the fuel pressure was bleeding off pretty fast. I know it is supposed to bleed down, but didn't know how fast. I only had the ignition on at that time. And yes,I did mean that with the vacuum disconnected it was higher, and lower with it connected when the engine was running. It was 40ish when connected, and upper 40s when disconnected.

As far as the minimum air goes, I tried doing it according to this website, but the car wouldn't stay on no matter what I did. I guess I'll retry it because the car stayed on for a little bit today, so maybe it will tomorrow when I try.

 

also chaeck you fuel flitter i had a prob like this on my it would idle go then you could go ran fine let off and flop died out what mine was was the gunk in the tank was cloging the fuel fliter when i was off the gass pressure was higher even though i was off the gas so change fuel filter ill look up some more for ya

 

I had a throw out bearing go bad and the motor would die as soon as you push in the clutch.

 

I was going to change the fuel filter. I've changed it a few times. As for the clutch, it's actually new.

 

possibly bad injectors. pull the large vacuum line off the brake booster, and listen as someone turns the key to the on position. it should be silent. if you hear hissing and the fuel pressure drops to 0 in under 15 minutes, you have a stuck open injector.

this just happened to me... mine would drop in less than a minute. i think it was 3 injectors that had stuck... but you could hear it quite clearly with that vacuum line off.

 

That's odd. Mine runs fine. Always has, just like every other TPI I've ever worked with. I follow standard diagnostic procedures. You should try it sometime.

 

Perhaps you're missing something here vader.
I was referring to the fuel tank/pump assembly.
The person that posted this thread has a non-running car,so I really have no clue what you're talking about. Anyway,glad to hear that yours runs fine,mine does too for now.

 

I had similar problems. My IAC was bad.

 

The best money I ever spent on this car was for a Factory Service Manual-it has paid for itself many times over.

Forget Chilton and Haynes, get a Factory Manual, published by Helm.

 

Agreed. The fuel pump is no fun chore, and could have been done differently. I thought it was a more general statement.

The suggestion to follow diagnostic procedure was intended for the original poster. Testing actual fuel pressure would be a good first step. Instead of replacing the EGR blindly, perform the diagnosis of the system. You may have to reset the throttle minimum air position screw (NOT an idle RPM screw) and TPS before you solve the problem(s). The procedure for that has been posted here numerous times. You'll need to have the engine at full operating temperature, disconnect the IAC, and set the stop to maintain 550 RPM.

 

Well I wasn't planning on replacing the EGR blindly..

As for the minimum air, I've tried numerous times and thought I had it done right. I read later that it has to be at full operating temperature to do it. My problem with that is, when it gets to that temp, it won't stay on at all. When it's cold, it runs pretty well..sometimes. As soon as it gets hot, it will surge for about a minute, and then die.

 

Please, someone. You have to know something that can help me. I just replaced the knock sensor because I couldn't get it to time well without jumping around. It seems to be a lot better now actually, but when it gets to operating temps, it starts to just die. No rough idles or anything. Just falls on its face. Help me, please.

 

probably injectors. you have touched on almost everythign else. are they the originals?

 

It seems as if you have two problems to first focus on.

Yes but it also may be as simple as a broken vacuum line to the egr valve. If you have the electronic temperature sender on the egr did you connect it? My 89 has this I'm not an expert enough to know if yours has this. PM me with your e-mail I will scan the 89 diagnostic sheet for egr to your e-mail. Should work the same for yours.

First things first, get the egr working correctly, then....

If your car won't idle how are you managing to set the IAC? That 1and 1/8" you mention is just an initial pintle length so that you don't damage it when you install the IAC.
Can you turn the mimimum air screw in far enough and force the engine to idle at any rpm?
If you can then read the tps voltage try to set it between .54v and .60v.

Write back if you get the EGR corrected, erase the code after you find the problem by disconnecting the battery for 10 seconds.

 

You keep asking for help. This is a very basic test and will start you to realize what is wrong. Slow down and fix something, before asking about everything.

This test will tell you if the IAC is set correctly or if the egr is leaking. You have fiddled with enough stuff already to totally confuse the original problem.

You just know, you have done it right, even without testing and verifing. Goodluck.

Rule of thumb clear all codes first.

There wasn't a code when you started now there is. Something has changed, and it needs to be corrected first.

Then set the idle.

Do it as many times as it takes to get it right. If it doesn't idle, don't move on, stay at it till it will stay running.

Anything else you do will be just be a waste of your energy and money.

 

Ok,, here's what I'd do if you brought it to me. First, I’d rap on the MAF sensor to see if that made any difference in idle,, then unplug it to see if that made a difference. If it checked out OK,,, knowing that the transmission was recently pulled for a clutch,,, I'd make sure there were no wires pinched somewhere and all the grounds from the engine to the firewall were good. If so, fix that and hope it didn’t fry the ECM.

If that checked out OK,, I'd check/set the base timing - unplug the timing wire, get it at 10-degrees,, cut the car off, set the min idle speed by jumping aldl pins a and b,, turn key to the on position (not cranked),, wait 30 or 40 seconds, unplug the connector to the IAC.

Pull the jumper off the aldl, crank the car (IAC and timing wire still unplugged), use the idle screw to get the idle to 500rpm, cut the car off, adjust the TPS to read .5 volts.

Crank the car and reset idle screw to idle at 500 (IAC and timing wire still unplugged) if needed. IF you had to idle it up or down,, cut off car, check TPS to see if it is between .45 and .55 volts. If so, leave it for now. Then, crank the car and reset the base timing back to 10 degrees (IAC and timing wire still unplugged) - it will be off if you moved the idle speed screw.

Cut the car off,, set min idle speed again,,, and keep repeating this whole scenario until you get the car idling at or around 500 rpm with the TPS at .5 volts and the base timing at 10 degrees with the IAC and the timing wire disconnected.

Once you get that dialed in,, and it may take three or four repeating cycles (depending on how off the idle speed screw was to begin with), cut off the car, hook up the IAC and the timing wire, disconnect the battery for a couple of minutes, then crank it up.

Check the timing,, the car should have around 26-degrees timing at idle (depending on how much your particular chip puts in it) and idle speed should jump up to around 650 rpm. If the timing doesn't jump up to around 26-degrees, there's something wrong with the computer.

If you do all this and the car still will not idle,, pull the throttle body, clean it out, put it back on the car then repeat the whole cycle again. If after cleaning the TB,,, it still won’t idle,,, or will until it warms up, there's something going on when it hits closed loop. At this point,,, you’re going to HAVE to get a scanning tool to see what’s going on (as others have suggested). An intermediate ECM problem is the hardest thing to pin point and that would be my guess if you did all this and still had trouble,, but get it scanned before you replace anything else.

Hope that helps.

 

Ok so I just kept trying over and over to set the minimum air properly and it finally worked, but I had to have the idle set at around 1000-1100 for it to idle with the IAC disconnected so it's idling around 1500 now. Should I keep doing this procedure until it goes down lower? But besides that, it's running great. Better than it ever has since I've owned it. I took it for about a 30 minute ride and absolutely nothing went wrong, but when I was pulling in the driveway the SES light came on. I checked it immediately and it was a 15 which says Coolant Temperature Sensor. I've read that there are more than 1 of those and would like to know if there is a way to find out which one it is, and how much it'll affect the car. Thanks for everything guys. Sorry I didn't slow down and just put a little more effort into this before.

 

right in the front of the manifold, there are 2 coolant sensors. one has a fuel injector type plug, the other has a weatherpack type plug. the second is the cts that the computer uses to operate the engine. if thats jacked up it will do all sorts of interesting things to your idle and engine operation.