Milkman

Hi everyone, I'm new here. Got a 92 Cavalier RS, 4 cylinderthat I've been doing some work on, replaced 2 motor mounts, fuel filter, plugs etc.
Car drove fine to work on Friday, then at lunch time, was only running on two cylinders. Cylinders 2 and 3 are not firing, but 1 and 4 are. I pulled the wires one at a time to find this out. I'm getting spark out of all of the wires. Can you have a bad coil if there is still spark?
I'm taking a class at the local Auto Repair shop and go in on Tuesday night. I have access to lifts, so any suggestions before then would be appreciated.
I was looking to the injectors also. Could two of them go bad or dirty at the same time. Any other suggestions?
By the way, I just had a new catalytic converter put in to replace one that had "corked".

Milkman

cctgene

My guess would be that you have a bad coil housing.

Milkman

We changed out the ignition coil that the two dead cylinders are connected to, took a compression test and the two dead ones are lower than the other two, changed and gaped spark plugs, checked for vacumm leaks, and still have the same problem. This problem occured quickly. Drove to work fine, and at lunch time when I started the car, it was like someone had pulled the wires off the two cylinders. Gonna change the wires, as the spark doesn't seem to be right. I'll get back to here, but if anyone has any other suggestions, please let me know.

Milkman

cctgene

Correct me if I'm wrong, but I think on the GM distributorless ignition system for a 4 cylinder engine that one coil pack provides the spark for the the number 1 and number 2 cylinders and the other coil pack fires on the 3 and 4 cylinders. If that's the case then your not getting the proper spark on half of each coil pack. Try swaping the coil packs and see if makes any difference. Based upon what you've said my guess is that it won't. If there is no difference then you need to look at what is common to both coils.

The fact that you have low compression on the two non-firing cylinders could be due to your flooding the cylinders with gas and that's washing
away the oil and you don't have a good seal on your rings.

Milkman

Two and three run off one coil, and 1 and 4 the other. 2 and 3 is the one we changed. The numbers are stamped on the original coil packs that way, as was a diagram I got off another site.

cctgene

I looked it up and you were right about the coils. Have you checked to see if you can hear the injectors clicking on the two bad cylinders?

Milkman

We were going to use injectors testers on Tuesday night at the shop. How would I go about checking the clicking sound of the dead ones? Do I turn the car over andlet it run.? I believe there is gas getting into the cylinders, but if the injectors aren't working properly, could it just be flooding them out and keeping them from firing?

Milkman

cctgene

What I normally do, if the car will run, is to start it up and place the tip of a long screw driver on the injector and then place your ear on the other end and listen for the clicking sound that comes from the injector opening and closing. What the clicking sound tells me is the injector is not stuck open or closed and it's getting an electrical signal.

When I hear that two adjacent cylinders are not firing with spark the first thing that comes to mind is a blown head gasket. What were your readings when you did the compression check? Also, you indicated that you had spark but how did you verify that? What I do is put a timing light on each wire and look for the flashes and for any irregularities between cylinders.

Milkman

I can hear clicking at the two good injectors, and the other two have sound, but not like the clicking of the two good ones. How do you remove the injectors to clean? them if they are sticking open? If their sticking open, would this flood the cylinder enough to keep it from firing?

Milkman

cctgene

Check out the following site from Autozone they have a pretty good write up on injectors:

http://www.autozone.com/az/cds/en_us...rInfoPages.htm

What I do sometime if I'm unsure if an injector is bad is to swap them around and see if the problem moves. One thing you might think about is, how probable is it that the two injectors would go bad at the exact same time.