Hey guys I'll try and keep this as brief as possible. Keep in mind I've done a ton of searches on this, and have found a lot of info, just can't find any solid answers that apply to me. Car is an '89 Camaro IROC-Z 350 TPI.

Symptoms:
---Wants to stall as soon as I start it up in the morning (engine is cold). I have to put my foot on the gas right away to keep it from stalling. Then I have to give it like 3 minutes to warm up before I leave.
----Once it is up to temerature, the car has a choppy idle and "surges" when I'm in traffic. Every once in a while it will stall on me like when I'm going slow in a parking lot.

What has been done already:
----AC/Delco IAC valve and O2 sensor, cleaned out EGR and TB, replace all vacum lines, PCV valve, and this has all been done after a good tune-up.

Tomorrow I plan on checking the TPS once my dad brings home the voltameter. After that, I'll let you guys know what I find.

Just wondering what else it could be? I was thinking maybe MAF relays?

Oh, and how do I go about checking the injectors? While I've got the voltameter home, I might as well check everything. Tell me what you all think. Thank you.

 

Anybody?

 

Do check the TPS for proper voltage or replace it. My old tps was right on .54v and over 4.0+ on WOT but on every cold start-up I still had to press the gas like your situation. I replaced the following: Maf burn off relay, Maf Power Relay, CTS Coolant Temperature Sensor, EGR valve, new sparkplugs/wire, IAC valve, but still yield the same problem every morning. I bought a brand new TPS for the hell of it and sure enough it solved the problem. No more cold problem startups and it idles perfectly. Be sure to have set at .54V and reset your computer by disconnecting the battery. Good luck.

 

Yesterday I attempted to check the TPS but the voltameter ws jumping all around. It was going from .1 up to .8 so it was impossible to get a reading. I didn't use the paper clip method that I read about after the fact. I will try again today. I un-plugged the battery yesterday, and it seemed to run a little better but I have no idea why.

How do I check the voltage on my injectors? Do I use OHMS? Thanks.

 

O.K., checked the TPS voltage today. I had much better luck....it was right at 3 milivolts. I loosened it up and moved it to where it was reading 4-5 milivolts and tightened it back down. Went to start the car and the idle was up at 1500! WTF? How do you guys adjust this thing without the idle going crazy? So I returned it back to the stock location since I don't feel like breaking my neck when I put the car in gear. Does this mean I need a new TPS sensor ($40)?

Now to the MAF relays.....when I check the kragen and autozone websites, all they show is a "MAF relay".....they don't show a "burn off" or "maf power". So do I need to get both? If I get the one they sell, will it which of the two relays will it replace? Thank you.

 

You may need a new TPS sensor. The maf burn-off relay and maf power relay have the same part number. If you check your old part number they are exactly the same thing.

 

85 views? C'mon guys, help me out here!

Today I put in two new MAF relays. Didn't seem to help much, maybe a little. Tomorrow I will be moving onto the TPS and will probably just replace it. Might also check power on injectors....how many ohms should I be looking for on the injectors? Does just the ignition need to be on?

Oh btw, I took off the entire MAF/air filter assembly just so the engine was breathing throug the TB and the idle was still bad, so thank *** it isn't the MAF itself.

 

Hi,

I had a posting sometime back when I documented all the things I tested. Do a search and see if you can dig it up.

In my case, the car started fine, but still had the surge. I've tested and checked pretty much everything and it still surges from time to time. I suspect a sensor is almost out of range.

Since yours stalls on cold days, that is different. Typically, if it is hard to start, and you have to put your foot down, it may be fuel leaking from the injectors when you shut the car off. The fuel drains into the intake, and you have to open up the throttle when you started. Just like it is flooded. It's a rather long process to check for leaking injectors.

Your TPS voltage seems very odd. At idle it should only be 0.54. You said you had 3.0! That is not right.

Do you have access to a scanner that can read the computer data? Not just the error codes, but the data?

Do you have a vacuum gauge? Just curious if you have a severe leak when it is cold. It does not sound like that, but something to check.

Mark.

 

Nope, no scanner and no vacum gauge. I think I just might replace the TPS. As far as the injectors, if that's the case, I will just have to live with it for a while until I get my new engine next year. I just hope they aren't causing the bad mpg.

 

Double check your timing with advance wire disconnected.

 

lol, I don't have a timing light either. What is the advance wire for? Why must it be disconnected?

 

You need to use a light to get it accurate...
Disconnecting the wire is necessary so the ECM doesn't advance the timing. Think of it this way..the computer constantly adjustst the timing (even at idle), if you move the distributor with the wire hooked up the computer will compensate, also you won't be able to see the timing marks (the usual advance at idle is off the scale ~20*), You need to disconnect the wire so that you can set an accurate base and it should match the base timing set in your prom....

 

if you replaced your iac valve and your tps voltage is only .3 volts at idle, i'd start with the obvious and go from there. you need to follow this tech article to set your minimum air and tps voltage correctly. https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

 

Alright, when I adjust the IAC, am I pulling the whold IAC out, or am I just disconnecting the wire to the IAC? When I disconnect this and start the engine (to adjust throttle) where will the idle be? I mean is it going to be way up high to where I will have to hurry and do everything or will it be idleing normally? Thanks all.

 

had the same exact problem on my 85 5.0tpi, and my 88 5.7 tpi , both times it was a faulty maf .... ouch very expensive! but it sounds like you have exactly ther same symptoms! not what you want to hear but I hope this helps?

 

Well, I don't think it is the Maf because when I disconnected all the intake stuff so that the engine was breathing just through the throttle body, it was still pretty rough, so fortunately I ruled out the maf being the culprit.

 

By disconnecting all this stuff, the car will still run poorly. It is still reading even though the snorkel is not hooked up. But anyway, I have this same problem right now with my 89 5.7 and it sucks monkey *****. It seems to get a little more and more under control as time goes on. This seems to happen really bad every few weeks. Another episode of sorts. But lately it has been damn unbareable. I start it up in the morning and it wants to die, So I give it gas and it sounds ugly. I can let it idle for a good 5-10 minutes, my carbed 86 didn't even need that long. When I take off...... it lurches through 1200 rpm and then smoothes out when it gets above that. Come to a stoplight and its the same thing over and over, until the cars been driven for a good while.
Another thing I noticed is the idle surge, from like 700 to 1000 up and down.... pisses me off. My temp gauge has also been on the blink. It will read the temp if I start the car cold. If I turn it off and restart, it will stay down around 100 degrees and never come up, which I know is ludacris because there is no way the car is staying that cold when it was at 180 30 seconds before...... What gives?

I will try a new TPS, what else should I change while I am in there. I am contemplating a swap to SD so I won't have to deal with these mafs anymore. Any help would be appreciated fellas

Will

 

Sounds like we're in the same boat here. The surging was a little better the past two days since I replaced the Maf relays...I'll see the truth of it when I fill up though. If it hasn't got any better, I'll be messing with the TPS/IAC.

 

what you're doing when you put the ecm in diag mode and turning the ignition on is making the iac valve extend all the way out. you have to leave the ignition on and disconnect the plug from it to keep it from operating when the vehicle is started. if you turn the ignition on and then back off before you unplug the iac valve, it will idle way high even if you back off the idle screw all the way. after unplugging it, start your car and use a t15 or 20 torx bit (i forget which it is) to adjust the idle screw on the throttle body. once you get the idle set to where it should be, shut off the car and plug the iac valve back in. MAKE SURE YOU TAKE THE JUMPER OUT OF PINS A AND B! then, turn the ignition forward again (but not started) and hook a meter to the tps. i forget which wires right offhand. first, adjust it so that it is .54 volts w/ the throttle closed. then after you tighten it back down, slowly go to wide open throttle and watch the meter. the voltage should progress to over 4 volts at wide open throttle and the voltage should increase pretty much smoothly without it jumping around. if it does jump around, your tps is junk and get a new one. after you get this done, i'd unplug either your battery or the wire by the battery that powers the ecm for 5 or 10 minutes and then hook it back up and go for a drive. see if that fixes ur problem

 

the TPS should be at .50-.65 at idle, and 4. somethin at WOT. I'd check the fuel pressure . to check the injectors, you can use a noid light,but it only shows if they are firing. You can pull off the whole fuel rail and watch the injectors spray"do them into a cup or something" you want it to look like a mist from all the injectors.
but it doesnt sound like an injector problem.

 

Thanks guys, just wondering if you can give me a step by step procedure on how to do this. It's still a little sketchy to me on when to plug the paper clip in and when to take it out of the ALDL. And when you say to take the plug off of the IAC, you don't mean to remove the entire IAC, but just the part that snaps on? I also don't get what the point of messing with the ALDL is? I think a procedure will help. Thanks again. You guys will be my hero if I can get my gas mileage up.

 

you are only jumpering a and b on the aldl port in order to make the iac valve extend all the way out. so, after you've gotten to the point in the tech article where you unplug the iac valve, you can turn off the ignition and remove the jumper(after iac is unplugged). DO NOT START THE CAR W/ PINS A AND B JUMPERED. the ecm won't like that. after the jumper is removed, then you start the car w/ iac unplugged and proceed to set minimum air (idle speed) with the screw on the throttle body.

also, you do not remove the iac valve itself when doing this. just unplug the wiring connector that is on the end. (see pic)

 

Alright, tell me if this is right:

Jump A and B with paper clip, turn on ignition, wait 30 seconds, unplug IAC, turn of ignition, unplug jumpers, start engine, adjust to 450 rpm, turn off engine, re-connect IAC, start engine, turn off after checking idle (@ 650), turn on ignition and re-set TPS, turn ignition off, unplug battery for 10 minutes.

So how does this sound? After doing this, and I find that the TPS is bad (can't get a good reading), will I have to do this procedure all over again, or will the new TPS bolt right in with no problems? Oh, and if the TPS does require some adjustment, it should be very small adjustments to the right and left, correct?

 

everything looks good except this. you don't really have to do this step until the very end.

If your tps is bad, you will only have to adjust the new one to the correct voltage after you replace it. you won't have to do anything with the iac valve.
you adjust the tps by loosening the two bolts holding it to the throttle body and moving it up and down.