Shift9303

Hello everyone, my car is an '00 AP1 with around 65K miles. As far as I am aware it was well maintained by the previous owner. When I pulled into the parking garage at work I noticed the car felt like it was down on power but it was still running smooth and I was in a hurry so I parked it and didn't think anything of it. After starting the car when leaving work the CEL instantly turned on. It flashed for 1-2 seconds and then turned solid. We read the engine code as cylinder 1, 2, and 4 misfires. Idle was rough and shook the car severely. The car felt like it was very down on power but above 4K RPM or so the car felt like it was running normally. Car seemed like it had trouble keeping idle but when applying throttle the engine would smooth out. When looking under the hood we noticed the MAP sensor had come loose from its latch but not fully disconnected; we reconnected it but the car still seemed to have trouble at idle. Then we also checked the spark plugs which didn't look burnt or anything out of the ordinary, but we replaced them anyway. Upon restart after this the codes changed to cylinder 3 misfire and random misfires. Finally we decided to reset the ECU by disconnecting the battery and then having the ECU relearn idle as idle seemed to be the main problem it was having. This appears to have fixed things as idle returned to normal and power seemed to be back to normal as well.

Tl;dr:
1. CEL misfire codes
2. Uneven idle though higher RPMs seemed ok
3. MAP sensor was loose
4. Replaced spark plugs
5. Reset ECU and relearned idle

Car appears to run fine now. Could all of this have been caused by a loose MAP sensor? Do you guys have any other input on things I should also check or things I may have missed?

Thanks in advance!

windhund116

If it seems okay and there are no CEL... just drive the thing. Think that you found and fixed the issue.

Good driving!

akirakun

Same as above, no CEL good to go! Mine ended up being bad coils. Rough idle, sounded like a Subaru. If it's running fine after your adjustment, I'd not worry about it too much.

Shift9303

Funny you mention coils. My car was acting up again this morning. Luckily a local shop had an opening so I brought it in. My problem ended up being coils, guess my buddies and I missed it while trouble shooting.

landapanda

If you changed all your plugs, my second guess would be the coils. Move the bad coil from the misfiring cylinder to another cylinder that isn't misfiring. If the misfire moves to that cyl, you have a bad coil. I've had this happen twice and luckily it was only the coils and nothing more like injectors.

roel03

I've seen 3 different cars act this way and it was coils on all three. If you let it linger on one cylinder it will spread to all four. Make sure to replace the whole set, not just the problematic coil. Amazon has them with prime for cheap. Use AP2 coils, even on AP1.