fulmnte

My parent's 88' IROC 350 has been running hot lately, so with the advice of some from the forum I removed their thermostat, flushed the system three times (until it was clean), and then installed a 180* stat with the four small holes drilled in it. Everything had been working good until I took the car off the ramps and set it in the street for a bit.

I went out to start it again (after about 15 minutes) to see if it needed more coolant and it would not start. The engine would crank, the battery was fine, but it was like the car was getting no gas and there was a "Service Engine Soon" showing on my dash. I checked everything and double-checked the throttle-body because I disconnected it to take the stat out and I noticed that the vacuum tube was disconnected from it so I plugged it back into the throttle-body and it still wouldn't start. I even disconnected the battery a few times and the code would come right back.

I then checked for any codes. 12-12-12. Absolutly nothing to go by on this. My neighbor suggested putting starting fluid in the intake so I did and the car started fine! I drove it for 10 minutes and it seemed ok, although the SES light was still on. I checked for codes again, nothing but 12's. I then let the car sit for about 5 minutes, went out to start it again and it took about 10 seconds for it to start (normally, it is instantaneous), but it did start. I then drove it for 30 minutes and it still seems to drive fine, but the SES code is still there. It did seem to stutter a bit while driving around town.

I'm at a loss as to what might be going on and I really hate to have to take it to the dealership so they can charge me a ton and tell me they don't know so I'm really hoping you guys can help me out.

Thanks!

fulmnte

Just a quick note. I have started it twice since my last post, and the longer it sits, the harder it is to get it started. Don't know if that would help much.

Vader

Does the SES lamp lamp flash briefly when the ignition is first turned on?

fulmnte

I don't think so. If I am starting the car, it will usually be off until about ten seconds of running the engine, then the SES light turns on and stays on (other than the one time it turned off for a few seconds while driving around town). If I try to check the codes, the light turns on and off very fast, and then gives me the 12's.

fulmnte

I just went out and tried to start it after having it sit all night and it wouldn't start. I also double checked my codes and it looks like I'm getting a code 21 as well as the 12's. 21 appears to mean the the throttle position sensor signal voltage is too high. I'm not sure how to fix this, but it makes sense since I had to remove the throttle body to get to the thermostat. I never disconnected anything from the throttle-body, other than the coolant pipe going to it so I'm not sure why I would be having problems with it. Perhaps that little screw that holds the throttle in place needs to be adjusted? I'm going to do some searching on this code, but I'd still appreciate some instructions.

Thanks!

edit: I went out again and it wouldn't start, I disconnected the battery and the SES light came on, but this time only gave me 12's! This is confusing as hell.

edit2: I found the articles on cleaning the IAC, adjusting the min air, and adjusting the TPS so I can try that out tonight, but shouldn't the car at least start if the TPS is messed up?

fulmnte

I went home at lunch today and did this:

Tech Articles - Adjusting Your TPS

I then drove it for about 15 minutes with no light and everything was great. I then stopped at home, turned off the car for about ten minutes, came back out and started it and I got the SES light again! So I got out my voltmeter and my voltages were really high. About the lowest I could get it was 2.50 vs. the .540 I had the first time I fixed it. I checked the other line going into the sensor and I have 5v, so I don't know where I'm going wrong now. Perhaps a new TPS is in the works? I don't know why changing the coolant would cause that though.

HELP!

Thanks.

8492bird

You stated that you disconnected the throttle body in order to access the T'stat - make sure the TPS is installed with the lever making good contact with the throttle arm.

fulmnte

Isn't the throttle arm on the oposite side of the TPS? Or is this on the inside of the throttle body?

8492bird

It's right next to the TPS - the arm extends through the throttle body and there's a tang that the TPS lever engages. Look between the TPS and the throttle body and push on the throttle arm - you'll see what I'm talking about.

fulmnte

Is the part circled in yellow what you're talking about? If so, how should it look?

Do they have to be touching at all times?

fulmnte

Wow, I'm checking my TPS voltage and the lowest I can get is around 3v.

Any ideas/

fulmnte

Well, unless anyone has any miracle ideas this thing is going to the dealer in the morning...

8492bird

That looks right - one last check you could do - remove the TPS and with wires connected and key on, engine off check the voltage while moving the TPS lever. If the lowest you can get is still ~3V you have a bad TPS. If it goes down to ~0 then it probably was'nt engaging properly.

This is a good case of no good deed going unpunished. All you did was flush the cooling system and change a T'stat and the TPS took a dump!

fulmnte

I think you're right, the TPS is junk. I drove the car to work this morning and no SES light, so I think the TPS is flaky at best. I feel bad though because I probably did $75.00 worth of damage to the car, and it's not even my car. My only hope is that f I had taken it to the dealer to flush the system they would've ran into the same thing.

Oh well, I'm going to take it to the dealer in about 10 minutes. I'll keep the thread updated as to what they find out.

Thanks for everyone's help!

fulmnte

I drove it to the dealer, no SES light at all. They found the same code, but couldn't get the light on. They were able to get the TPS calibrated to the right voltage, how I have no idea, but they seem to think the TPS is good. I guess I'll drive it and if it happens again I'll just order a new TPS and install it myself. My only problem will be that the bottom screw on the TPS is stripped, so hopefully I can find something to replace it if I need to change the TPS later.

Can't wait to see how much this cost me.

Dizturbed One

aw man, you shouldn't have taken it in yet. lol

for a problem like this those guys are just a ripoff, too expensive to justify

that stripped screw itself might be part of the problem... maybe it wont sit at the right voltage because it moves around in there once it's been working awhile

i would've fixed that screw with a drillbit and some helicoil first.

fulmnte

I would've tinkered with it more if I had the time, but since this was my parents vehicle and not mine, I didn't want to screw around, especially since they wanted it back.

I think I may have stripped the screw when I was fooling around with the TPS, so I'm fairly certain that wasn't the problem since I had the same issue before then. Also, I came right home after forking over $70 for them to do hardly anything to the car and plugged in the voltmeter. It was reading 1.65v at the closed position, which strikes me as odd since I think it was supposed to be around .55v!?

Oh well, it works for now, so I guess I'll just leave it at that, I still think something is fishy about that voltage...