Interesting Problem

[forester801]

Ok, this problem has thrown me for a loop. I can't seem to figure it out so I have joined this forum in hope that someone has had the same problem and found a solution.

It all started about a week after I did an oil change. I used castrol syntec. It was a 5L jug and i just poured the whole jug in. About a week later as the car is warming up it would suddenly drop in rpm and just turn off. If I went to turn it on it would start then die right away. If I wait 10 minutes it would run just fine. I have a check engine light on so I scanned it. It said P0420 catalyst efficiency below threshold bank 1. Before the oil change it did run a bit hesitant and I know my post cat o2 sensor is reading lean. So I went ahead and just unplugged the 02 sensor and ithe hesitation went away and it drives great. But the problem with it turning off still remains. Now here is the part that throws me for a loop. when it turns off OBD2 says= Ignition coil primary/secondary circuit and it shows 4 codes A,B,C,D. for each coil. I know all 4 coils are not the problem. The part that really loops me is that once it dies two or three times after I wait and keep warming it up it runs just fine and will run fine all day. But once the morning comes and the car has been sitting getting cold it will do it again during warm up. Mass airflow sensor seems fine, coolant temp sensor reads 80ish degrees.

So today what I have done was replaced the fuses and relays for EFI and Coils. I also drained the oil as there was about 1 litter too much and am now waiting for my car to get cold to see if that changes anything.

My main question is: Is it possible that too much oil would cause your car to turn off? And what other causes can you guys think of? There is no unusual smoke or colours coming from the exhaust, no foul or awkward odours either.

Any hints would be greatly appreciated!

Thanks so much guys.

Chris.

Update: I started it again with the correct oil level and it still turned off on me. I am stumped.

[hardtopte72]

You probably have a bad ECU. There was a recall on the ECU for all sorts of problems (shutting off, loss communication, erratic shifting,).

Take it to the dealer and have them check and see if your car applies.

Short of an ECU you might have a connection issue at the ECU or at the main junction block (on the drivers side fender area).

[forester801]

Found the problem. It was the ignition coil ground wire.