P0300, rough idle, sluggish acceleration, low power--FIXED
Mar 31, 2017 9:05:08 GMT -5
Naeos_Valkarian and ryanex like this
Post by hank0604 on Mar 31, 2017 9:05:08 GMT -5
I posted my troubles in another long thread on this subject, but wanted to post a new thread with what ended up fixing it so that didn't get lost in case anyone else is dealing with the same issue.
History: the problem came on suddenly during a long drive from Texas to Colorado and back. I was at a stoplight and the engine started stumbling at idle and my CEL came on. I scanned P0300 with my code reader, cleared it, and kept driving--light came back at the next full stop. Other than the rough idle, it seemed fine except that I was having trouble maintaining highway speed on any sort of incline and I didn't seem to have much power when I needed to pass someone. I wrote it off as either high elevation or the low octane gas they have out there and finished my trip. Problem persisted, so I started replacing things and running tests.
Attempted fixes (some of these I knew weren't likely but wanted to address all facets of the air/fuel/spark/compression requirements for ignition): new air filter, cleaned throttle body, new fuel filter, and checked all vacuum lines. tested throttle position sensor, IAC, and cam & crank position sensors. Replaced plugs and wires. By unplugging each coil one at a time with the engine idling, I narrowed it down to the 2/5 coil not firing, so I replaced it. No go. Compression test, all good.
Final fix: used a spark plug tester to determine there was no spark coming from that coil, despite knowing the coil was good. Went back to the factory service manual and read everything I could find on the ignition system and found a multimeter test for the "power transistor." Which seems to also be the ignition control module (ICM) according to what comes up when I search for each part. You apply 1.5v to a couple terminals of the transistor and measure resistance between a couple others. For the terminals that go out to the working coils, it was exactly 6 ohms--for the one going to the 2/5 coil, it was 10 ohms. So I went to the junkyard, pulled one for about $12, and put it in. I also replaced the ignition condenser with a junkyard one, but I don't think that was the problem as it wasn't broken until I broke it when removing the ICM. Anyway, as soon as I started it up I knew it was fixed. Went for a test drive and it was amazing, like driving a brand new car. More acceleration and power than I can remember that motor ever having.
TL;DR -- if you're having P0300 and sluggishness issues, try testing your power transistor/ignition control module.
History: the problem came on suddenly during a long drive from Texas to Colorado and back. I was at a stoplight and the engine started stumbling at idle and my CEL came on. I scanned P0300 with my code reader, cleared it, and kept driving--light came back at the next full stop. Other than the rough idle, it seemed fine except that I was having trouble maintaining highway speed on any sort of incline and I didn't seem to have much power when I needed to pass someone. I wrote it off as either high elevation or the low octane gas they have out there and finished my trip. Problem persisted, so I started replacing things and running tests.
Attempted fixes (some of these I knew weren't likely but wanted to address all facets of the air/fuel/spark/compression requirements for ignition): new air filter, cleaned throttle body, new fuel filter, and checked all vacuum lines. tested throttle position sensor, IAC, and cam & crank position sensors. Replaced plugs and wires. By unplugging each coil one at a time with the engine idling, I narrowed it down to the 2/5 coil not firing, so I replaced it. No go. Compression test, all good.
Final fix: used a spark plug tester to determine there was no spark coming from that coil, despite knowing the coil was good. Went back to the factory service manual and read everything I could find on the ignition system and found a multimeter test for the "power transistor." Which seems to also be the ignition control module (ICM) according to what comes up when I search for each part. You apply 1.5v to a couple terminals of the transistor and measure resistance between a couple others. For the terminals that go out to the working coils, it was exactly 6 ohms--for the one going to the 2/5 coil, it was 10 ohms. So I went to the junkyard, pulled one for about $12, and put it in. I also replaced the ignition condenser with a junkyard one, but I don't think that was the problem as it wasn't broken until I broke it when removing the ICM. Anyway, as soon as I started it up I knew it was fixed. Went for a test drive and it was amazing, like driving a brand new car. More acceleration and power than I can remember that motor ever having.
TL;DR -- if you're having P0300 and sluggishness issues, try testing your power transistor/ignition control module.
