help! bouncy idle and black smoke? - BMW Forum

MarqE36 · 05-07-2006, 01:13 PM

After recently replacing my DME since I wet/fried the old one. My car idles weird as it bounces up and down, just shorty after it's a but warmed up. Also when I revved it up, it's blowing black smoke, and at idle it doesnt seem to. Also note that I have fuel flooded the engine (fuel even leaked out of my CAI) from trying to start it over and over when my DME went out.
I have also replaced the spark plugs, the old ones were black.

What could possibly be the cause of the unstable idle and black smoke?

saltshaker185 · 05-07-2006, 01:23 PM

try a compression test... im thinking that the fuel ate through your piston rings...

325isBaby · 05-07-2006, 08:33 PM

Unless you left the car flooded for a year I doubt fuel ate your rings...the fuel would have had to have had long enough to seperate to eat the rings. But sure do a compression test. Chances are that your car is still trying to clear the crap out

MarqE36 · 05-07-2006, 11:35 PM

Since I flooded the engine from trying to start it several times to swapping the new DME and finally firing the car back again; it has only been about 5 days. I have only fired the engine 2x since and 4-5min idle and few revs. well I really hope its not the piston rings. Again only when revved higher it smokes black, I didnt really notice any at idle..

would it be a good idea if I drive it around the block and see if the smoking will eventually clear up? do you think it could just be my oxygen sensor?

325isBaby · 05-08-2006, 12:07 AM

It takes a little longer than 5 days for the fuel to seperate, and it is EXTREMELY rare occurance to have fuel "eat out the rings" Drive the car around for a while and see if things improve before you worry more (you did flood your car afterall it will take a while to clear out the crap because of it) and PS if it was an o2 sensor you would have a MIL

MarqE36 · 05-08-2006, 12:20 AM

Thanks! I really hope so. You just made me feel better and much relieved all day! So tomorrow Im gonna drive it around for some while and see if things do improve. Yes, no check engine light on my OBD-I. MIL? I wonder if there is any additive I can use to help clean out my combustion chamber to speed up the process.

325isBaby · 05-08-2006, 12:22 AM

It's gonna take time, additives or not good luck

MarqE36 · 05-08-2006, 03:42 PM

drove it to school and back today and no more smoke / lumpy idle within a few minutes! =)

antonk · 05-08-2006, 03:54 PM

As far as I know, whenever you get a new DME, you have to drive around for a bit so that it can program/adjust itself. It was just sending too much fuel to the engine, thus the black smoke. Looks like after driving it a bit it has improved, and I bet you'll never see this "problem" again... until you replace the DME again.

MarqE36 · 05-09-2006, 12:41 AM

yup driving it sure did the trick. I just dont get the last part of what you said, why it wont happend again until I replace the DME again. Just doesnt make sense, and I just did replace it with a new one.

antonk · 05-09-2006, 01:21 AM

I just meant that this problem is gone... the only way it should come back is when you get another ECU... again it will be new and need to be programmed, so it will cause the black smoke and weird idle until you drive it some.

MarqE36 · 05-09-2006, 09:26 AM

oh ok now I got ya. hopefully this will be the last DME I've ever swap in, since it soo damn expensive. It better be the last. Reword: It will be the last!

325isBaby · 05-10-2006, 12:02 AM

Glad I could be of service, and that's great to hear