My issue is one I've seen a lot with these cars but never seem to find an answer for. I'm driving an 88 iroc with 5.7 tpi and I bought this car roughly 6 months ago. The previous driver said that it had a 'cold-start' issue and that if I let the car warm up for a bit it would run fine. It had no gauges hooked up, no interior, most of its interior electrical systems were hacked and spliced and a terrible paint job...to say the least it ran which was a step up surprizingly.

About a week after receiving the car, each day it ran about the same as the last, all of the sudden one cold morning sent the car's reliability out the window. It would start but I couldn't put it in gear without the rpms dropping and the car shutting off. I work as a tire technician at a local tire shop and know several mechanics so I pushed the car to the shop with a series of slamming on the gas, starting the car again after it shut down and praying.

Since then I've replaced more than I care to remember but will try to do so as it may help with the diagnosis :

At first we thought about the basics : Vacuum, spark, air, fuel.

We found a leak at the plenum which turned out to be a gasket...no change but fixed the vacuum problem
Replaced and upgraded all plugs, wires, cap and rotor to msd also with no change
Checked fuel pressure while the car was in park and it came out to somewhere between 40 and 47...which I'm told is good
Checked and set timing to the emissions spec to no avail...then advanced it to 2 degrees higher to see if it would help...it didn't
So that left air as the only possible problem and thus we decided it was the MAF's fault

I didn't have the money at the time to buy a MAF so the car sat for 3 months

Finally we got an experienced mechanic in who told me to replace the fuel filter...which I did...the second he heard the car he realized timing wasn't correct and so we ended up adjusting timing to 15 degrees from 8 which got the car running and moving but instead of stalling completely when switching gears it would only stall if the car wasn't warmed up enough yet and when accelerating after a complete stop the car would sometimes stall no matter how much or how little gas it got.

Since then we have done several tests and here's what we have found :

We did a compression test which found that all 8 cylinders are good...so bottom end checks out

We checked tps for irregular voltage throughout the movement range in throttle possition and everthing was fine there too

We noticed that the number 2 and number 3 injectors were leaking and so we replaced them to no avail

Finally we tried checking the chain for slack and found an excessive amount of slack, some 15+ degrees, and thus we changed the timing chain...

After much prayer the car started and ran a little bit better...now when I press the gas from a full stop the car bogs for less than two seconds and then takes off normally, it still needs to be sufficiently warmed up before it gets put in gear. It usually only bogs down one time while driving but when it does it sometimes backfires.

I did however get a bit of good news during the recent few days of working on it, my friend owns a 92 rs and has bought also a 84 HO which he sold me the interior out of. I've got working lights, working gauges, even a nice looking interior thats going to be finished within the next week. Speedometer is correct, voltage is correct, gas is correct, and the tach is only about a grand off but the coolant gauge doesn't work at all...it always reads 100...I replaced the sensor only to have the gauge shoot to 220 whenever the car starts the plummet back to 100 for the rest of the trip. Even worse my check engine light is always on and no amount of paperclip to the a and b terminals can cojole it otherwise.

I'm pulling my hair out because I can't check the codes... and my shop diag tool only goes back to 1992. Am I gonna have to pay someone to check my computer out? Thats the last thing I want to do...anyway thanks for your help in advance.

 

is the backfiring out the intake or the exhaust, does the pedal feel like it " Pops down" when u hear it or?

 

when I check under the hood as it happens it feels/sounds near the intake

and yeah I think it "pops down"... the pedal kicks a bit I think...I'll try and pay attention next time it happens.

 

you may just have the exact same problem i had, lol

Maf fixed the whole thing try to get a wells maf there better though
but dbl check before u buy it there kinda expensive

when i ended up checking myn i had a trouble chart if u have a manual and a multimeter shouldnt be a problem

Id try to replace the relays 2 my burnof relay made a big differance even to my old maf sensor

 

Something that can cause really strange behavior but will not show up in any codes is a bad fuel pump. Ask your mechanic to do a voltage ramp test on the fuel pump. This will ensure that the pressure will change with a voltage applied. I had experts tell me to replace ECM's MAF's all sorts of sensors. Finally found a mechanic who knew TPI's and we replaced the PUMP and all was well?