'87 Firebird with issues

[Ciara]

I've been having some issues with my '87 Firebird for about a month now. It's a V6 auto, and hasn't had any issues until recently. It's consuming gas at a rate that rivals my V8 'Stang, and the idle is quite rough. That went on for about two weeks, with me unsuccessfully trouble-shooting it. Then, it started to die on me immediatly after being started. It fires up fine, but the RPM bottoms out and the vehicle dies unless you keep your foot on the gas. However, if you rev the hell out of it or drive it for several minutes, it usually behaves itself. It started throwing a check engine light about the same time, so after hooking it up to a scanner, I came up with a bad mass airflow sensor. Replaced that, with no change in the behavior of the vehicle. Finally took it to a garage, and the mechanics there are at a loss to explain its erractic behavior. I had the fuel pump relays checked, as well as the fuel cutoff switch replaced, since I suspected initially that some loose wiring there might be a cause for the dying upon startup...but everything checks out good. As for the fuel consumption issues, it's not leaking fuel while running or while off. Any ideas/suggestions? I'm getting desperate, as I need to have this car reliable and ready for a 2000 mile trip in a month....

[tacoma man.]

did you disconnect your battery after replacing the mass air flo sensor? and also i would replace the oxygen sensors, a car this old, they need replaced, my camaro done the same thing, you can get them at advance outo parts for $20 and i beleive that you will need 2, not sure tho, my v8 camaro uses 2.
but it was so bad that i sucked a full tank in two days, after that i could drive it through out the weel and still have gas left to do half of the next week.

[FormulaLT1]

Is it still throwing a MAF sensor code?

[Ciara]

Actually, I disconnected the battery for the replacement. I always do when I'm playing with anything electrical. So yes, the computer was reset. Didn't seem to help.

I'll look into replacing the O2 sensor(s). Don't know much about them on this car, so I'll have drop by garage and get them to print me up something on it. Don't like to go in blind, ya know?

[Ciara]

Originally Posted by FormulaLT1

Is it still throwing a MAF sensor code?

I'm assuming yes, but I haven't been able to get back to the garage to use their scanning unit. They're on base, so they're closed today, and I don't feel like paying anywhere off base sixty bucks to do what I can do for free.

Funny thing is, it doesn't consistently immediatly throw the 'check engine' light upon startup. It does about 90% of the time...but the other 10% it doesn't. Of course, as soon as the car dies on me, that changes, but still.....it's an interesting problem.

[FormulaLT1]

I would see if you can have it scanned again to see what codes its throwing cause if the wiring is good and the MAF sensor is good and the correct voltage is being given to the MAF. Then I would think your problem is a bad ECM.

[Ciara]

Yeah, that's what I'm afraid of. I had a chevy that had near the same problem...and replaced just about every sensor I could think of, before giving up and changing the ECM. Solved everything.

[FormulaLT1]

Yup they have been known to cause all the problems your having and stump many a mechanic. Good luck and let us know how it turns out.
John

[Kurtdg19]

It does sound like it could be the ECM. If everything else is to check, the only other thing I can think of would be a vacuum leak at the intake.

[Ciara]

Well, now it's throwing two codes. The MAF code, and an EST wire code. Apparently it's grounding out somewhere....I'm going to look at the MAF heating relay, and make sure all the wiring in that is good, since it (visually) looks to be a bit jury-rigged...and I'm going to see if I can't find where the EST wire is grounding out. Also need to replace the set screws on the throttle positioning sensor....which is likely also part of the problem. Once these three minor things are out of the way, I'll see if she's running any better. Should be fixed by the end of the week. If these take care of it, great...if not, back to looking at the ECM...and also the fuel pressure. I still think it might have something to do with the fuel pump or O2 sensor, the way the car is consuming gas...Starting to look like I may have a lot of little problems, instead of one or two big ones.
(Forgive me if I've screwed up any terms....electrical is something I don't do, so I'm relying heavily on my mechanic for info right now.)

Oh, and I've done a vacuum leak check...well, the poor man's version of one, anyway. Nothing showed up.