90 Lumina Sedan Problems, plz help.

[fat_Boy27]

I havea 90 lumina with a 2.5l in it. It will run evenly at idle or very very slow accelleration. If you place the engine under a load it will studder, pop back, and possibly die.
I've replaced the MAP, tps, fuel pressure reg, ignition module, injecter, crank senor, ECM, fuel pump, fuel filter, plugs, and wire. Check engine light isnt on, and there are no codes when we run the test. I really appreciate any help you may give me.

[Bridgett]

I am having the EXACT same problem I know this post is old...but did you get it fixed? I am DESPERATE!!

[tblake]

I had that same problem with my 1990 2.5L 4 cylinder. Turned out being the cat converter the 1st time. never got it fixed the 2nd time, but try there. Or also maybe the O2 sensor. Good luck.

[Bridgett]

Thanks we will check the Converter. Don't those put off a bad smell like sulfer when they are bad? We replaced the O2 sensor a couple of days ago...but never thought about the Converter. Thanks!

[richtazz]

I'd also check the EGR valve, and the passage that leads to it

[Bridgett]

We replaced the EGR and checked the passages. Thats why this whole thing has got us so totally stumped. I mean we have replaced darn near everything there is to replace...checked Voltage everythere there is to check it.....just don't know what to try that maybe we have missed....Frustrating

[richtazz]

Do a compression check, both with the engine cool and warm. Take the plugs out and check for variations between adjacent cylinders. They shouldn't vary more than 5%, and no cylinder should vary more than 10% from any other. You may have a blown head gasket or cracked head that is only leaking combustion, not antifreeze or oil. If compression is ok, pull the valve cover and use a dial indicator to check valve movement. You may have a worn cam lobe or bad valve spring.