93Cavi22

My '93 Cavalier with the 2.2L and auto trans was missing lightly at idle and failed emissions with a 285 HC when the limit is 220. I replaced the plugs and plug wires, changed the oil and air filter. Now, it starts hard, really stumbles and shakes at idle, and needs gas before it will start moving. It appears to smooth out while moving, but at stop lights it really shakes and almost dies. No codes are set. Could it be that I put the wires on the wrong plugs? I don't think I did, but since the system uses the "waste spark" ignition where two cylinders (1+4, 2+3) fire together, could I have a crossover? Or is the coil pack bad? I note that there is a DIS (direct ignition system?) to fire the plugs up to 400 RPM, and another ECM controlled system takes over above that.

The Chiltons manual has a diagram of where the wires are supposed to go on the coil pack and cylinders, but the lines connecting the numbered terminals do not match with the numbers. This has to be a typo, has anyone noticed this? Where can I find the definitive diagram for wire connections? Any help will be appreciated.

93Cavi22

So, I found a useful diagram for plug wire connections on autozone.com, and I didn't switch any wires. I still have that random, strong missing problem at idle and low speed. I can hear stumbling at higher RPMs as well. Does someone have an opinion on whether it is one or both of the coil packs ($27 ea) or is it in the ignition control module ($137)? Or maybe the crank sensor? No codes are set, so probably not the sensor. The next step is to get the whole system out and test it.

kevinkpk

Well, since you suspect crossed plug wires, try swapping two at a time.

93Cavi22

It's not switched plug wires, I checked. Also, not fuel, I have a brand new fuel pump, filter and pressure valve. Must be ignition...

Segfault

I'd do compression check in all cylinders, too.

93Cavi22

Problem solved! I went through the ignition system, including switching plug wires 1+4 and 2+3, pulling the coil packs and ignition module and having them tested at Autozone (no faults), I even switched out the ACDelco plugs for more recommended Bosch copper+ plugs - all to no avail, still missing like crazy. All this for a routine tune-up! I then remembered that I had dumped in one of those little bottles of Lucas fuel injector cleaners when I had only about three gallons of gas in it. I went and filled it up with premium gas, then drove around the block a few times in first gear, running it up to near red-line for a few seconds at a time, and viola! It fixed itself. Must have been some crud in the gas system somewhere that caked onto the injectors, even though I had replaced the fuel pump and strainers, fuel filter, pressure regulator, sprayed out the throttle body and cleaned the IAC valve as best I could just last month. It passed emissions and I am relieved after a month to have it fixed. I'm learning a lot about this automotive system the hard way.
Thanks to kevinpk and segfault for their advice.