Ok guys, here's what I'm struggling with... 1986 305 TPI i just pulled out of storage that just won't run right. Sometimes will start and idle, but most of the time it'll start idle around 500 rpm's for a few seconds and then die. Usually after stalling 3 or 4 times it'll start and idle up to 1100 rpms for 10 to 15 secs then drop down to 700 to 800 rpm's which I believe to be normal. Had a horrible miss so I changed plugs and wires, I found to melted wires where they had come loose from wire holder under the exhaust manifold. I also found one plug wire had come off entirely so I was only running on 7 cylinders! No idea how the heck it came loose??? So I figure this would explain the unburned fuel smell. I start her up and she runs considerably better, but still had a slight miss and my idle starts jumping around like crazy up and down back and forth. I get out my scanner and pull a code 34 MAF sensor. I search around here for at few days and decide I'm going to clean the MAF sensor, and replace my idle air control valve while I have the throttle body off to clean it. I had pulled the battery cable to clear the code, hook it back up after reassembling everything and start her up and took a minute for the computer to relearn and starts idling smooth and runs great. It ran so good I ran it to the local inspection station and got it inspected and passed emissions test!!! Next day I go start her up and right back to stalling and throws code 34 again. I search on here again and find some posts saying to check the relays. I swap the maf power and the burnoff relay and instantly starts and idles perfectly, lots of power, no miss or anything odd for the 40 minute commute home. I call napa and order new relays for the MAF and for the fuel pump. Next morning, the car starts hard, check engine light on again, idles low and stalls when I put it into gear. I nurse it to work get out swap the relays again idle gets erratic, swap it again idles smooth but has a miss again and smells strong of unburned fuel. Get the new relays in start her up runs great slight miss around 1500 to 1800 rpm's but otherwise runs ok, but not great. I start her up this morning and starts hard but idle up to 1100 rpm's, I figured I'd let it warm up good, go in to get my coffee and I hear the idle kick up and I run out and find it's idling @ 1500 rpm's and the lights on again... I hook up my scanner and it won't pull anything service engine soon light and choke light are lit solid!!! I wanted to bring it to work and check my fuel pressure and hook it up to our MAC scanner, but when I start her back up she goes right to 1500 rpm's with ses light on solid and stalls the instant you try to put it in gear. I'm thinking a few possibilites are I still need to do cap and rotor, and I always have trouble in the mornings when it's damp and we've had really heavy dew in the mornings. I'm also thinking dampness is screwing with a bad ground possibly, but not sure where to check. Then I'm also wondering if my computer is shot and acting up. Everything I've done has helped, when it runs good (typically in the dry afternoon air) the car runs better than she ever has before and will literally boil the tires off effortlessly. I'm just running out of ideas... Thanks in advance, this site has helped a lot over the past 2 years!

 

**update**. I just finished putting on the distributor cap and rotor, pulled battery cable to try and reset the computer with no luck. Started and stalled twice, 3rd time started and shot up to 1400 rpm's with the service engine soon light fully lit. Let it idle a few minutes with no change. Turned it off, and tried to pull any codes with no luck... SES light and choke light fully lit. Too dark here to work on it outside anymore tonight. To recap I have new spark plugs, wires, distributor cap, rotor, swapped my stock coil for an accel supercoil I had from my old truck. I originally had a code 34 so I cleaned my MAF sensor, and have replaced my MAF power and burnoff relays, I also replaced my fuel pump relay. I also replaced my Idle Air Control valve since I had the maf and throttle body assembly off to clean them. I'm running out of ideas, please help!!!

 

Did you reset IAC and TPS correctly after TB clean?

 

I might not have, what Is the proper procedure for setting the IAC and the throttle position sensor? I followed the directions that came with the IAC, but they were pretty lacking and were not specific to our cars.

 

I just found the FAQ post on IAC and TPS adjustment... No I apparently did not set either one properly, hopefully I can work on this tomorrow before it gets too dark. Hopefully this solves the problem. Has my computer gone into the infamous limp mode I see mentioned so often??? I tried searching for limp mode and couldn't find a description of the symptoms. Thanks for the response, and I welcome any other ideas anyone has that I should do. I love this car, I've had it for 2 1/2 years with no problems until I had to store it, I'm anxious to get it running right again and enjoy her for a couple months till the snow flies....

I bought this car because my late father had 2 IROC's, a black and gold 86 305 tpi auto and a Flame Metalic red 88 tpi with a 5 speed. I was in junior high at the time and some of my fondest memories are cruising in the 88 to high school football games etc with my dad. Everytime I drive in this car it's like stepping back in time to when my dad was still alive. Thanks for your help!!!

 

Ok, set tps voltage per instructions on this site. Could set idle voltage but my voltage @ wide open throttle fell way off... Also noticed the arm on the back of the tps was not returning properly, so I picked up a new one. Put it on set idle voltage again, got to check it @ WOT and it still falls off???? Fire the car up it goes thru it's relearn, idle nicely @ about 700 rpm's in neutral, 650 in gear. Take her for my 20 minute cruise and about 15 minutes in SES light comes on, slight miss under partial acceleration now. Drive home, hook up the scanner and get a code 22 ( TPS idle voltage low). Any ideas?

 

Just wanted to add the car ran awesome until the SES light came on, lots of power, no miss, and no eratic idling.

 

My car was doing something similar to yours. My buddy hooked a scanner up to it and he went through everything in the GM service manual. Then we got to the o2 sensor, the o2 worked but the computer wasn't reading it. Got a new computer and it solved the problem.

Not saying that's what your problem is, but that's how he found it.

 

I have to say that I've been wondering if the computer isn't acting up/going bad... It just makes no sense that sometimes this thing will run like a new car and the next time I start it up it runs like crap. I did just find another post by Vader that has different voltage readings for setting the TPS than the link I was following earlier. Does anyone know what the correct voltage settings are for an 1986 305 TPI are? This car is completely stock.

 

85'-88' 305 MFI (TPI) 0.45v plus/minus .04v key on engine off.
Question; did you disable computer timing control before adjusting the minimum air rate?
IAC minimum air rate in drive is 500 rpm. Be sure to set the hand brake and chock the wheels, or and have a buddy you trust to hold the brake.

 

If I'm reading the TPS adjustment post correctly, when I manually swing the throttle arm to WOT there shouldn't be a voltage drop, it should stay pretty constant. Mine drops all the way down to 1.03 volts... This is a new TPS just put on last night.

 

Ok, I tried again to adjust my new idle air control valve and throttle position sensor, not sure what I did wrong... I've followed the instructions posted on this site and I have a couple of problems. First I am wondering if I installed my IAC correctly, I did it according to the directions that came with my new valve, i found posts on here that say the pintle needs to be fully retracted? The directions I used said to adjust the pintle to 1 and 1/8" from the gasket mating surface to the tip of the pintle. Which is correct?
Second, my TPS voltages are way out of whack with what I've found here... Following the procedure I found on this site. My voltage is 4.5 volts @ idle, and falls to as low as 0.63 volts at wide open throttle, completely different than what I'm being told here.
I'm fairly new to computer controlled cars, I really appreciate any help and I'm sorry for my ignorance, please help if you can, Thanks!!!

 

How do I disable the computer timing control properly?

 

The quick disconnect is located just above the HVAC housing.
Here's a post with a picture, but is not where mine is located, I'll see If I can find the one I posted. The wire is tan with a white stripe.
https://www.thirdgen.org/forums/tech...-location.html

 

rgarcia wrote:
The quick disconnect is located just above the HVAC housing.
Here's a post with a picture, but is not where mine is located, I'll see If I can find the one I posted. The wire is tan with a white stripe.
https://www.thirdgen.org/forums/te...-location.html (EST bypass connector location??)
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here is my 86 IROC Z. on post #16, there is a picture of the location on our 1986's IROC's. Click on the link here to see where the EST wire (electronic spark timing), which is the wire that you must disconnect so that the computer wont control the engine, timing, ect. https://www.thirdgen.org/forums/tpi/...rs-i-need.html

 

Well I haven't had a lot of time to work on this, but Saturday she finally spit out a code 51 (bad prom or ECM)... I talked to Brian @ TPIchips.com and he said he thought it was more likely to be a bad ECM and not the prom. Started looking online used were about $60, reman were $125 to $150 online. I was having no luck finding one locally, so finally last night I called advance auto on a whim... $77.95 for a reman with a one year warranty!!!! Plus they had one there this morning!!!! Swapped it tonight and PROBLEM SOLVED!!!! Finally, this one was kickig my butt... Thanks to everyone for all your help, my car runs like a beast now, better than ever!!!! Thanks guys

 

Kragen has em too but you need to do the core exchange. I think the price is around $75 dollars.