Rough running 93 3.4L

[Mr_Lurch]

Can anyone help me out? I bought a 1993 3.4 Camaro for my daughter with 107,000 miles. It ran fine to begin, then we began having a cooling problem (nasty coolant). The system was supposedly flushed but we ended up blowing a head gasket. I usually do my own maintenance but this was the first time for me going this deep into the engine. Anyway the headgaskets (both since I was there) were replaced. One new fuel injector, new battery, new plugs, new plug wires, cleaned IAC valve, new PCV valve, new oil pump sensor, new fuel filter, new valve seals (one side only after that head was re-surfaced).

The engine is now back together and starts and seems to run fine at idle in park. Put any kind of load on it, in drive or sitting at a light and it wants to die. It sounds and runs rough and feels like the timing is off. all wires are correct acording to the chiltons manuel. (passenger side 1,3,5 and drivers side 2,4,6). At fifty mph it starts getting rough again and jerking. Whats going on??????

[89IROC&RS]

well with that much work, it could be alot of stuff, do you have a check engine light????

[Mr_Lurch]

I dont have a check engine light on. A neighbor who races a 2002 z-28 says that it is miss firing in one cylinder. I've done ohms tests on the wires and coils, all checks out o.k. The car seems to run fine at idle, but doesnt any real power and at 50mph it really starts jerking, if I accelerate out of that range it smoothes out, but it still has no power.

If I disconnect the EGR connector there is really no change at idle, if it is revved up it wants to die when it slows back down but doesn't.

With the blown headgasket, could any of this be caused by the cat or muffler???

[berkes454]

could be....check all your wires maybe one got burnt from touching a exhaust manifold

[yorkkm]

might be your O2 sensor also - water + O2 sensor bad

[Xbox2202]

Crap, it seems that the 3.4L engines have a huge disease of busting head gaskets it seems. I bought mine about a month ago, and since mine busted, I've seen two other people on here alone that had busted head gaskets.

[351wStang]

To find which cylinder or cylinders are missfiring or to simply rule it out do a simple check. Its quick and easy. Go one spark plug wire at a time while in drive or reverse with someone holding the brake or with just the E brake on if its good. Pull the wire off and away from the plug. If the engine starts to run worse plug it back in. Do this until you pull a wire that doesnt change the rough running of the engine. At this point inspect the wire for any problem whatsoever. If you find nothing visual then it could be that its breaking down inside (although I doubt this with them being new). If you dont find any problems with the wire pull the plug. The gap may be out of spec. If this doesnt fix it check the dist cap to see if there is anything wrong with the little nipple thingy for that cylinder. Or replace the coil pack if you dont have a distributor. Sorry dont know too much about these newer Camaros so I'm not sure if its DIS or not.

[351wStang]

Also just happened to think, if the wire is burnt and the spark is making the jump then there is a good possibility that the electrode is burnt out of that plug. But this would normally be for a worse running condition than you are explaining.