1.8L W/Service Stabilitrak & Traction Control, Flashing CEL, rough idle, etc. Help!

12412 Views 12 Replies 8 Participants Last post by Maqcro1, Jun 10, 2021

JillOfAllTrades

Discussion Starter · #1 · May 14, 2016

1.8L W/Service Stabilitrak & Traction Control, Flashing CEL, rough idle, etc. Help!

Got off work one day, hopped in, started my baby up, and she started all these crazy symptoms. I limped her home and parked her. Replaced the valve cover assembly and spark plugs, put her all back together, started her up... Same problem. Ran codes, got codes U0100 & P0304. Thought maybe I hadn't gapped spark plugs properly. Pulled them back out, checked the gap, .028. Ran codes, got the same result. Cleared those codes, I get a permanent P0300. Engine runs fine after ignition for about 30 seconds, then I get the service stabilitrak/tcs, and cel flashing-- engine starts rough idling. Checked all the lines, etc. Replaced the intake cam sensor... Replaced the champion spark plugs I just installed with AC Delco 41-122s, put it all back together. Same results.

The initial codes are U0100 and P0304. Once I clear those, I get P0300. I'm stumped. Faulty coil maybe?

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Maqcro1

· Premium Member

Joined Apr 29, 2019

887 Posts

#13 · Jun 10, 2021

JillOfAllTrades said:
So I removed both ECM fuses for a few minutes, put them back and started the engine. Ran okay for about 30 seconds, then bogged down to a rough idle and lights come back on again. I pulled the codes and it just says P0304 now..... how do I test to verify if the coil is the problem?

there is no test for our coil pack due to the design. There are multiple mosfet transistors wired in series along the assembly. Best solution is to buy a coil pack assembly and see if it fixes your rough idle. If nothing changes return the coil pack 😆. Code u0100 is a communications error and can be many different things.