I have a 1994 Camaro 3.4L, it has right around 122k on it. I've owned the car now for about 2 months. Typically when I get a new car I do the basic tune up on them, plugs, wires, filters, etc. Well when I went to change the plugs a friend was helping me out and unfortunatly the wires were crossed when we were done, well started car up of course didn't run to well, switched wires started with a puff of white smoke and ran rough, finally got the firing order right and it ran ok after that. Well before I had changed the plugs and wires it had alot of power and would chirp the tires with barely any gas. After plugs were changed the car has been idiling very rough, the engine surges when idled in park, idles around 1100 to 1200rpm then down to about 900 after it warms. It seems like it is missing the whole time though. When it is parked or I am braked it's so rough it shakes the entire car. There is no check engine light on. It is a 94 so can't hook it up to a scanner. I don't want to take it to a dealer because it seems there diagnostics run quiet a bit, a base fee of $104 but can run up to $450. Also around 45 to 50mph it starts to kinda sputter, shakes, and just run like crap. If I give it enough gas it backfires then stops sputtering but it will shift and then start doing it again it is at lower rpms when it does this. I found that if I'm careful and regulate my gas it's not quiet as bad. I thought I fried some of the ignition having the wires crossed so I have replaced a few things thinking that this would fix the problem of the miss, backfire, and surging. Also when driving it at speeds under 45 while giving it steady throttle it it still surges, but almost like it's clearing up and then it goes back to running like crap. Sounds kinda like weee,wooo,weee,wooo sorry for a bad attempt at making the noise but thats the best way to describe it. I checked the wires, replaced them twice, replaced bosch plat plugs with ac delco making sure they were gapped correctly. 3 new coil packs, new icm, new iac, and it still hasn't fixed the problems. I also put a new muffler on but it has a little leak after the cat. I did put a can of 44k in the gas tank seemed to help a little and I have ran a few top end cleaners through it, hasn't cleared the problem up. Occassionaly I smell gas when I get out of the car. I have been searching for the symptoms but unfortunatly so many things have similar symptoms so it's hard to pin point. I have checked for vacuum leaks, haven't found any. Bad injectors? Bad EGR valve? Bad cat? Could changing the plugs have caused the injectors to clog somehow? It has been so frustrating trying to figure it out. Any help would be greatly appreciated, I would like to be able to experience a good running camaro but am lost. Thanks so much. Josh

 

Apparently your tune up screwed things up. Sound as if the plug wiring is still crossed, or not making good contact. You may want to revisit them and see what the plug condition is. Also check all wiring near where you have worked, in case you disconnected something.

Also, who told you that the 94 can't be scanned? All you need is an OBDI scanner, or a scanner that does both OBDI and OBDII. Has to be a real scanner, those little $30 code flashers won't work on your car.

You can get a cheap set of NOID lites and verify all injectors are working, and cheap spark tester to verify all plugs are being fired. Fuel smell is probably due to the misfire, and could also mean the initial misfire events caused the cat to overheat and destroy itself.

 

I changed the wires 2 times, I have checked all the plugs 2 times, I have checked the firing order more than twice, everything is correct in that aspect, they all spark good. Check engine is not on, as I understand it needs to be on in order to even use the OBDI to pull a code. The light has never came during any of this. I forgot to mention I did also replace both of the O2 sensors. How hard is the NOID lights to use? Can they be used without taking the whole intake off and stuff? I'm ok with some mechanical aspects of cars but fumble when it comes to doing anything with the fuel system. Thanks.

 

The NOID lamp is inserted between the Injector connector and the injector, you should be able to disconnect the injector wiring without taking things apart. You may also want to check the fuel pressure with a gage while you are at it.
The check engine lamp does not have to be on to check for retained codes. A scanner will also allow you to look at the output of all the sensors and see if they make sense for the conditions. (like a temp sensor showing 40 deg while you know it is around 200 deg. The PCM is just like any other computer, garbage in = garbage out. lol