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GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15181
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Have 2004 cavalier ls. Two middle plugs not firing. Checked

Customer Question

Have 2004 cavalier ls. Two middle plugs not firing. Checked coil pack and no fire coming from two middle boots but outside two are firing. Car runs like crap. Bought new coil pack and replaced it, car wouldn't start. Took coil pack back to part store and got another one. Put it on and car won't start. Put old one back on and car starts, running on two cylinders. Any Idea what I need to do?
Submitted: 1 year ago.
Category: Chevy
Expert:  karrs2fix replied 1 year ago.

Does it look like the fuel injectors are working, are the plugs wet with fuel?

Expert:  karrs2fix replied 1 year ago.

I have seen a lot if issues with the ignition control module on those vehicles. It is the module that attaches to the top / end of the valve cover.

Customer: replied 1 year ago.
Middle two plugs are wet
Customer: replied 1 year ago.
Would car starts with bad module on old coil pack and not start with new coil pack?
Customer: replied 1 year ago.
Would module work on old coil pack but not new one?
Expert:  karrs2fix replied 1 year ago.

That is difficult to say why that is the case without monitoring the signals from the computer and the ignition control module. It is possible that the other coil you purchased was bad also

Expert:  karrs2fix replied 1 year ago.

Unless you have a scope to test the signals at the module and for the coils I would recommend you replace the ignition control module as it is a fairly common failure

Customer: replied 1 year ago.
I tried two different new ones and car wouldn't start.
Customer: replied 1 year ago.
Could it just be the module and my coil pack still be good?
Expert:  karrs2fix replied 1 year ago.

Yes it could be just the module as the failure

Expert:  karrs2fix replied 1 year ago.

You may need to utilize a scan tool to retrieve any failure code information and reset the computer after the module is replaced

Customer: replied 1 year ago.
I appreciate it. I'm gonna change module and see if that's it.
Expert:  karrs2fix replied 1 year ago.

Great plan, let me know if you need further assistance.

Expert:  karrs2fix replied 1 year ago.

Did you replace the module, how is it running?

Expert:  karrs2fix replied 1 year ago.

Did you need any further assistance? Did the ignition module fix the problem?