OutsiderIROC-Z

I am having issues with my 85 TPI IROC and am about at my wit's end. I will try my best to describe it and what happened when it started giving me problems.

I was driving it on a street that turned from overlaid asphalt to brick and the transition had quite a bump. After driving over this bump the car did not want to run at anything over idle and at times wouldn't even do that. I was able to limp it home by repeatedly pumping the accelerator pedal and such to keep the RPM up. Even though it was close to a full tank of fuel it acted to me like it was out of fuel or starving for fuel.

First thing I did was change the fuel filter. We then hooked it up to a fuel pressure gauge and it was anywhere from 45-60 psi if memory serves me correctly. Next thing I did was change out the throttle position sensor TPS as mine was kinda beat up and had some of the plastic broken off. That didn't help either. The voltage reading does not change when the throttle is moved. I then swapped in another computer and piggy back module (1985 one year only) and didn't see any improvement with that either.

The car will start and idle and if you get aggressive with pumping the throttle it will eventually clear up and rev up, but as soon as you are off the gas the RPM drop like a stone and it will die.

I know this is a long post and I hope I didn't leave anything out. If you have any ideas or thoughts about where to look next I'd sure love to hear them.

Thanks again.

chevynutman

unplug your mass air flow and see if it runs better engine light will come on but it should run with some hesitation but should run ok if it runs better you need a new maf will only fit 85 tpi 86-90 are all the same but 85 is different


i also have 85 iroc tpi did the same thing drove it around unplugged for six months until i got up the nerve to drop 190 bucks on that little piece of plastic

OutsiderIROC-Z

Well, I tried unhooking the MAF sensor tonight. It definitely ran worse, but it was worth at try...

I can not help but think that the TPS needs adjusted. Is there a procedure for doing this?

chevynutman

sorry that didn't work was worth a shot.

can you get the engine light to come with it running or only when it stalls.

also check map sensor and vacuum lines-some lines have vacuum at idle and some have it off idle -not sure how to check map/maybe block vacuum line or unplug that too

oh ya egr valve supposed to be closed at idle and open as you speed up i know it sucks to get to it but you try tapping on it to see if it closes

let me know how any of these work and i'll try to think of something else

go2fast

No MAP sensor on an '85. I think you're probably right and you still have TPS problems. The voltage should change. You might want to try some contact cleaner on the connector end and/or ohm out the connections between the TPS connector and the ECM. There's a lot of info on thirdgen.org including how to adjust the TPS.

chevynutman

ooops! forgot mine didn't have a map just going through the problems w/possible issues that could cause them

chevynutman

are you still having problem with car

if you are did you check your iac valve

mine started acting up about a week ago had to turn up idle screw to keep it running until i could check it out

finally got to check it today and found iac valve stuck got it freed up and reinstalled it,turned down idle and runs perfect now

mikeatwo

sounds like a catalitic converter,the inner linning of the converter can break away from the housing and while it may not make the car loud it can cause it to stall,run like crap and even do what you are describing.since its a 1985 it would be amazing if the converter was not rotted inside.i think when you rev the engine up your moving the metal around enough to clear the passage to register high rpms.going over the bump would certainly break the inner linning of the converter away if it was in the condition i described,i would bet this is the problem.if you get the car on a lift and look at the bottom of the converter you will see that there are rusty water stains coming from inside ,this means that the inner linning came apart.

OutsiderIROC-Z

Haven't had a chance to work on it lately, but am open to suggestions. It doesn't really have a problem idling...

OutsiderIROC-Z

Thank you for the suggestion. I had the catalytic converter removed several years ago. I am about ready to put it up for sale as is and see what I can get out of it, I lack the time and/or patience to try and chase down the gremlin...

I do appreciate all the ideas and suggestions though, and keep them coming if you have them!

ws6transam

My best guess is: Bump = wiring. Check the connectors on and in your distributor, plus unplug your ECM, re-seat the PROM, then reinstall it.

lordmetalz28

indeed,, i second that it has happened to me as,well

OutsiderIROC-Z

I have swapped ECU's on it and the wires there were tight, but the distributor is a good idea to look next...