M42 misfiring/bogging a WOT

[totheredline]

So I recently dropped an e36 m42 (with E30 M42 sensors and manifold) in my 318is. For some reason, I can't quite figure out, it misfires at WOT when its at operating temperature. Its will run totally fine and not misfire at all at half or even, 3/5 throttle. As soon as you open up thr big butterfly it misses. It sounds like a damn subaru and it has no power. If the needle is anywhere below center, it will usually run fine. I'm getting spark from all 4 coils, fuel pressure is where it needs to be, no vacuum leaks that I can find. Would a temp sensor cause a misfire like that?

Anybody have any ideas??

Sent from my XT907 using Tapatalk

[kwill22]

o2 or temp sensor id think. they're giving input that affects engine performance based on temp. test the sensors or if you havnt done it in a long time just replace the temp sensor since its so cheap. o2 on the other hand. if you go the ford route and solder the wires to your connector thats a cheap route but id rather go OEM.

[Lee22]

i just started having a similar issue, except mine is running on 3 cylinders even at idle. except today when i started the and it was running normal until i rowed through 1st, 2nd then in 3rd after 3000 RPM it started to misfire again.

[jntar]

had this problem. Oil leaked down into sparkplug on number 4 cyl and ended up killing my #4 coil. New coils and new plug wire fixed it. Was weird because it was fine for daily but at anything past 3/4 throttle it would misfire.

[Lee22]

I did the "stomp test" and got code 1222 Oxygen Sensor Lean/Rich Detect (primary)

also used the Peake tool and got a code "C9" which i believe is "Lambda Control"

[kwill22]

Reset the code and drive to see if it does the same thing. If so replace it. is that the only code?

[Lee22]

Reset the code and drive to see if it does the same thing. If so replace it. is that the only code?

UPDATE: i replaced the O2 sensor and did what you suggested, drove the car and it was fine when i did drive it for the first few minutes, it was not misfiring and then i shifted into 2nd gear (even below 3000 Rpm this time) and the misfiring started. checked the Peake tool and re-did the stomp test, NO codes.

i hadn't started the car for 3 days, tonight i did, now the car is misfiring even at cold startup. Still no fault codes since i cleared them last week. this is perplexing.

[kwill22]

How's your idle?

Are you running rich? Did you check the spark plugs, spark plug holes for oil, and test your coils? Inspect the spark plug wires.

Last time mine did this is was the temp sensor.

[Lee22]

i checked the spark plug in cylinder bank #3 which was the one misfiring, the plug looked nornal/gray color. i switched the spark plug to another bank and it works fine. need to switch wires/coils around and see if the problem follows.

which temp sensor were you referring to?

[kwill22]

Sensor in the head. If a specific one is misfiring then check the coils

[Lee22]

wanted to give you guys an update, seems the problem with my situation was the Fuel injector. replaced it and noticed there were some hoses that were also old and cracking under the manifold, so had those replaced as well. Everything is running smooth now, car starts up super quickly.