Whats wrong?!

[Ecrossdaily]

So I did an m42 swap not to long ago, and ive had this weird problem ever since. Here the vid: http://www.youtube.com/watch?v=8zPTpX0r2X0


When i start my car for the first time during the day it doesnt happen. I will turn my car off, and for the rest of the day it will do it whenever I turn on the car and try drive off. It doesnt go away untill I drive away and floor it. It takes maybe 2 seconds to go away and during those seconds it runs very rich, all it does is fart and make a popping noise out the exhaust., and has no power.

Took it to a shop, said compression was fine, cylinders were firing. Computer said nothing was wrong. So i tried my buddies air sensor, and it seemed to get rid of it. So i bought a new one. And it still does it. Replaced all hoses. Cleaned the throttle body and ICV. Im lost. I hope someone could help me out

Thanks!

[Ecrossdaily]

Oh i forgot to say, when the engine seems to kick in the first time, i disconnected the air sensor then plugged it back in.

[CorvallisBMW]

Still seems like it's the AFM to me, but there are other possibilities; coolant temp sensor, crank position sensor, cam position sensor... Do you have any spares you could swap out and start eliminating possibilities?

[Danny]

Afm, pull the plugs and take a look at them, how are your spark plug wires/boots?

[Ecrossdaily]

No, I dont have any spares. But dont you think the computer would pick it up if it was a sensor? Spark plugs and wires look good to me.

[Danny]

Have you tried a stomp test?

[Ecrossdaily]

I have a german 316i with an m42, it doesnt have the check engine light :(

[///digitalme]

this is what my car would do when i bent a few valves......but it could also be that its leaking air somewhere in the manifolds..you said you replaced the hoses so spray some carb cleaner and see if its leaking air...

[CorvallisBMW]

Does it still do the funky idle if you unplug your AFM? That's a clear indication of a faulty AFM since unplugging it sends the ECU in to a closed-loop mode during idle.

[KenC]

O2 sensor?

It only works when the car is warmed up, which may be why it doesn't happen in the morning.

[KenC]

Does your car have a catalytic converter?

[Eecen]

Have you tried the "hot start problem" fix from m42club yet?

Post 6: http://www.m42club.com/forums/showthread.php?t=7757

Edit: Nvm you did a swap...

[Ecrossdaily]

Does it still do the funky idle if you unplug your AFM? That's a clear indication of a faulty AFM since unplugging it sends the ECU in to a closed-loop mode during idle.

When It starts running like crap I unplug the AFM it seems to fix it for a a second or two. I Plug it back in and it usually fixes the problem..

O2 sensor?

It only works when the car is warmed up, which may be why it doesn't happen in the morning.

I just replaced the 02 sensor, Had to splice it in because you cant buy the ones with the right plug for the m42 wire harness.

Car does have a CAT yes a high flow magnaflow.

[Ecrossdaily]

Noobie



Join Date: Jun 2010
Location: Canada
Posts: 26
Have you tried the "hot start problem" fix from m42club yet?

Post 6: http://www.m42club.com/forums/showthread.php?t=7757

Edit: Nvm you did a swap...

Thank you so so so so so so much!

I think thats got it!

[KenC]

Thank you so so so so so so much!

I think thats got it!

That's why I asked about the catalytic converter. Glad it's working.