I'm trying to help my mom here. She owns an 88 firebird. 2.8L V6 MPI engine. Lately, she's been having ALOT of problems with the engine.
370,000 km's.. it's never been rebuilt, most of them are hiway km's. Here's the problems.. occasionally, upon acceleration, the car kinda' kicks back, and gives a couple quiet popping sounds. Then the check engine light flashes on and off, and the RPM's fluctuate like their having a seisure. Sometimes upon just idling at a stop light, it will staul out. It's also stauled while going into corners too :S.
We brought it to GM, and ask them to do a diagnosis on it. It's not the computer, not the distruibuter. It JUST had a complete tune up a couple weeks ago. the egr valve gasket, and exhaust manifold gasket were replaced. And after all this.. it still ran like crap. GM told us that they have no idea what's wrong with it, they just know that 3 of the 6 cylinders just quit, and that's when the car starts to act up.
I need ANYONE's opinion on what this could be??? We're so confused!

 

get a crate engine.

 

That would be soo nice, if only GM still produced them in ANY version!

GM does not make 60* crate engines any more. They stopped making the last 3.4 crate sometime in the last six months. But, if you are lucky, there is a seller on eBay that may have a few left. Do a search under the parts/accessories heading for "enginesdirect". He may or may not have some left, I am not sure. I haven't looked in a while.

Before you junk it, You might try checking the injectors and seals to see if everything is the way it should be. If the o-rings on the injectors have not been replaced in the lifetime of the engine, get that done first. Have the injectors checked and cleaned, or do it yourself. Check all of the vacuum lines. Have someone check the valve adjustment for you to see if any of the rockers have worked themselves loose over the years. Also check the timing. Those popping sounds may be the engine quietly backfiring. The base timing should be within a couple of degrees of 10 before top dead center.

 

Usually a flashing SES light indicates either a faulty emissions only device, or a corrupt PROM.

An EGR valve that is stuck open at idle will cause a large vacuum leak, and will make the car run rough like that.

Also, if the evap canister is purging at idle it can cause a rich condition. Never had it happen to me though, so I don't know if it would be rich enough to cause a misfire.

How did they verify that 3 injectors are quitting? Batch fire EFI systems only have one injector driver. It fires all six of the injectors at the same time. Each bank does however have it's own power supply (at least on the v8's). Maybe check for an intermittent open on that.

Only other thing that could isolate an entire bank of injectors would be something blocking the fuel rail on that side.

What was involved in the tuneup?

The popping sound is usually an indication of a lean misfire or a timing issue though. Just out of curiosity, did they put the car on an ignition scope and give you a printout of it? If you have it, care to post it up?