Great site, guys. Just joined to investigate possible purchase of 1987 Firebird with 2.8 V6 as project car to work on with my two oldest boys. Car we're looking at is in pretty good shape, but stumbles/misses when accelerating. Starts and idles OK, but feels like it's not running on all cylinders when accelerating. Have searched the board and sounds like most likely culprits are TPS or possibly MAF -- does this sound right? Other clues -- owner said he checked cat, was fine (even ran car without it to check), but that when he pulled the plugs, they were carboned up, so he replaced them. Any help/suggestions/advice greatly appreciated.

 

OK, still learning. Does the 2.8 have the same injection/emission system as the 305? Some sources list the MAF and TPS as V8 parts only...

 

Sounds like you need to start with the basic troubleshooting outlined in any haynes manual. Check or replace the cap, rotor, sparkplug wires, spark plugs (gap them correctly). Then Check and or adjust the timing. If you have done all of that, then is a good time to check out the sensors and distributor module. (cant remember if the distributor module was one that works or it doesnt, maybe.. *shrug* )

 

Thanks Redbird, but I'm pretty sure this car needs more than a basic tuneup. It starts easy and idles smoothly -- no misses caused by a bad ignition components or timing setup.

Anyone out there have a similar problem and solve it?

 

my fiero with the basically the same motor did the same thing and I had a plug wire arcing off the intake. Replaced the wires and all was well

 

Just in case anyone else out there has had similar problems, here's what fixed my rough running issue. FYI, I was getting a code 44 lean 02 sensor from the computer and the plugs were black.

First, I totally dismantled the intake system and thoroughly cleaned the throttle body and plenum (both halves) of all the carbon/soot/oil residue that had accumulated over 91K miles and 18 years. This included all air passges and the IAC valve. Cleaning the plenum was a nasty job, but I used lots of carb cleaner and even cut new gaskets to bolt on a couple of scrap pieces of wood over the ends so I could fill them to the top with cleaner and let it soak overnight.

I also sent the injectors out to be rebuilt by Cruzin Performance (on recommendation of a member). Turned out they were OK already, only one was a little out of spec, but at least I know they are all near-new now and should not cause me any problems in the future. Well worth it, IMHO.

I also replaced the PCV valve, because it was cheap and easy to do, and replaced all the vacuum lines, ditto.

Starts easy and runs smooth now, although it idles a little high, but I'm not sure I got the TPS set exactly right -- seems at the very end of its adjustment to get the right reading on the meter. Will have to try it again.

That's it for now. Have two very excited teenagers anxious to get the Fbird on the road in the spring. Once we fix the exhaust leak and finish the interior and do the bodywork and...