omnipotentgoku

iTrader: (1)

Im having a major problem with my camaro. I just started working on my IROC again (87 IROC, 5.7 TPI) and I am having this issue where the car will perform beautifully for about ten minutes (almost exactly 10 minutes) and after that it almost seems as though something just completely cuts fuel. From that point on, I cannot rev past 3000 rpm, and can only drive on less that 1/4 throttle. Any attempt to give it full throttle leaves the car sucking in gargantuan amounts of air, but not compensating with fuel, basically the car just sputters !! My air/fuel mixture pod suggests that its getting no fuel basically. Upon shutting her down and starting her back up a few minutes later, it runs properly again for a bit.


I've replaced the following items

Ignition control module
Fuel Relay
Maf Relay

My friends are inclined to believe that it is my MAF sensor. I am not one to say they are wrong, but thats one of those "expensive" parts I don't want to have to buy if its not broken so I would like to rule out all possibilities. Any help would be greatly appreciated.

formularpm

Have you replaced the fuel filter lately?

AaronIROCZ

iTrader: (5)

well if it is the maf sensor than just simply unplug it when you have the problem and if it is the maf sensor the second you unplug it the car will run better. .try that and let us know

BadSS

Yep, that was my first thought as well. If you have,,, is there any chance something could have gotten in the tank? Did you leave the cap off for any extended time, use an old rusted gas can to add gas,,, anything like that? Suction from the pump could be pulling crap against the sock filter on the pick-up tube cutting fuel flow. You cut the car off,,, the trash floats or falls off the sock,,, then it takes a while for it to be pulled back to it.

Do you see variances in your fuel pressure when this happens?

omnipotentgoku

iTrader: (1)

Actually I replaced the filter just before I started having this problem, no more than a month or 2 ago.,

Morley

O2 sensor. That 10 minutes of running good is more than likely when you first start it and are running in open loop mode. After 10 minutes you hit closed loop and loose it all....Yep, I'd start with the O2 sensor.

Morley

Now for a little rant.

why is it whenever someone has a driveability problem in a MAF car people want to immediatly say; "the MAF is bad"? Do they figure that since it costs $500 it must be the problem? When you have the same thing on a S/D car they don't automatically say; "the MAP sensor must be bad".
I have been running the same MAF sensor for 18+ years on my '85 IROC and it still works fine. If you don't fool with it then it has no greater chance of going bad than any other electronic part on the engine, less in some cases.

RBob

iTrader: (1)

That is almost too much of a coincidence. May want to double check that it wasn't installed backwards (arrow points toward engine) and even just replace it again in case it is actually bad.

RBob.

omnipotentgoku

iTrader: (1)

I would lean towards the fuel filter if the problem was persistent. Unfortunately howeve,r the problem is intermittent.... any other ideas ?

AaronIROCZ

iTrader: (5)

I am not trying to be cocky but how do you know the maf is good??? Did you unplug it and check to see if it runs any better??? It is one of the most simplest things to do and then you would know for sure it is good. I had a similar problem with my iroc, it would run fairly good when cold but when it warmed up it would pop, spit and sputter and have no power. I took it to the dealership I worked at and it took them a day and a half to diagnose a bad maf. I have never touched it either before this and one day it was bad. Just try to unplug it while running to rule it out if you haven't already.

bnoon

I have a similar self inflicted problem. Mine was/is caused by the long duration cam I have in the little 305... when it's cold, she runs great, but once it warms up it's a sputter fest... I was just wondering... do you have a custom chip? Any mods that would have effected the A/F ratio, hence is freaking out the 'puter?

Ed Maher

Sounds like it goes off when it hits closed loo. Could be a bad O2 sensor os something similar. Would not assume MAF since it runs OK open loop, which still uses the MAF, just no O2 corrections. Could happen that the O2 is pegging high or something and making it go hella lean on BLMs and toally bogging. Or the other way. Which would hit exactly......when it went closed loop.

omnipotentgoku

iTrader: (1)

Actually, I just put an SLP CAI intake on it .. could the increase in air intake cause the problem ?

Ed Maher

No, but not connecting something back up when you were done might have, and even that is still doubtful give your symptoms.

omnipotentgoku

iTrader: (1)

Im sure that reconnected everything properly...

omnipotentgoku

iTrader: (1)

I will be installing a new MAF this week so if that doesnt alleviate the problem, next will be the o2 sensor. ( I know the MAF is like a 3 minute job, I just have to wait for it to get here)

Morley

Isn't that kind of backwards? Start with the cheap component (O2 sensor0 and then the expensive one (MAF).

omnipotentgoku

iTrader: (1)

got an almost new MAF for 50 bucks, worst case scenario, its a part to hold on to because I am sure I will need it eventually.

Morley

naaa, 18 years on the same MAF.

SCCAjunkie

Anyone ever thought that the cats might be plugged?

Throw a vacuum gauge on the thing. Watch vac at idle. If your cats are plugged, your idle vac will drop as the car warms up. Another way to tell is to feel the exhaust when it starts acting up. Sitting in the driveway at idle, my exhaust was hot enough to fry bacon... from about 20 feet away...

omnipotentgoku

iTrader: (1)

Well, gotta breathe some new life into this thread.... still need some help folks. Since this original thread, i've taken my car to the mechanic and he has come to the conclusion that the problem is either my computer or prom. I have a 1987 IROC Z28 L98 5.7L 350 TPI, can someone tell me if this ECM would work for it despite what the auction says.

http://cgi.ebay.com/ebaymotors/ws/e...item=2432839235

Additionally, can someone recommend a place where I can get a prom replacement for this one cheap?


So far, all of the jacked up connectors have been replaced and most other options have been ruled out.

Trickster

I don't know about the prices there in Texas, but my dealership here has them for about $80.00 and they have the latest updates on them. Also, NAPA carries the ECM's. Don't know what their prices are though. I do know that if you get a new ecm from the dealer, they will charge a core charge if your ecm is not OEM from the factory.

The Trickster!!!!!!!!!!!!!!!!!!

RP1987GTA

STOP! before you replace that MAF replace the maf relays...........i've worked on 100's of gm MAF systems.....very rarely are the MAF sensors actually bad......but the relays are almost always the cause of a mAF related problem,even have had brandnew outta the gm box bad MAF relays.Plus guess what GM tells all its techs....REPLACE THE RELAYS BEFORE CHANGING THE MAF!!!!!

omnipotentgoku

iTrader: (1)

Are those the 3 relays on the firewall next to the Master brake cylinder ?

Trickster

Yes, the first one is the fuel pump relay, & the next two are the maf burn-off relay and the maf relay.

The Trickster!!!!!!!!!!!!!