Suspicious sporadic start

[andrewwynn]

BMW are very sensitive to voltage. A jump start is a one off to fix a battery run flat from leaving power on. You need to have a functional battery.

For testing purposes you could probably disconnect the dead battery and run off a host battery from a near car but don't try to leave a battery with a dead cell attached.

[Coleman El]

Okay. That's good to know. Didn't know that. So do you think that would make all tr h difference? What about the rough idling? After changing the throttle body and maf sensor? Wouldn't you think it would idle better or correct it for that matter?

[Corellian Corvette]

Jumpstarting a BMW in general is a pretty bad idea.

And yes, 100% you can royally screw up synchronization of your various modules with a bad battery and low voltage.

I had this same problem with an old e39 I was trying to bring back to life. Car started and I drove it home. Battery was bad, didn't want to replace it, and went to start it - CLICK. Died never would start again because the EWS lost sync. And it fried my Transmission control unit.

Spent WEEKS hunting through INPA to figure out how to resynch the codes and get it to start, and was fortunate an e39 TCU isn't coded to the car.

A painful lesson. Get a good battery before trying to diagnose other (esp electrical) problems.

Also +1 on a real scanner OR a machine with INPA. I use a Launch X431 mini

[Coleman El]

Wow! Had no idea. BMW'S are very finicky, I find. Will do that.

[Coleman El]

I'll post back afterwards. Oh! So in doing all this troubleshooting and long starts, how would I keep the battery from going dead?

[Mistermorgan]

looks like you're in good hands with Andrew here but just second what these guys have said these modules are so voltage sensitive, I would invest in a decent multi stage charger and keep that connected for these things also if you are ever connected to ista/programming keep it hooked to a charger.

Not sure if it has been suggested and might not be related because you are getting intermittent start but no fire but continuous crank could be a DEM/EWS misalignment. You mention you already have ISTA so maybe worth giving that a try, there are plenty of vids on youtube to show you how to carry out a DME EWS alignment with ISTA

[Coleman El]

Originally Posted by Mistermorgan

looks like you're in good hands with Andrew here but just second what these guys have said these modules are so voltage sensitive, I would invest in a decent multi stage charger and keep that connected for these things also if you are ever connected to ista/programming keep it hooked to a charger.

Not sure if it has been suggested and might not be related because you are getting intermittent start but no fire but continuous crank could be a DEM/EWS misalignment. You mention you already have ISTA so maybe worth giving that a try, there are plenty of vids on youtube to show you how to carry out a DME EWS alignment with ISTA

I appreciate that. And inhale been going back forth between here and YouTube, plus other member boards to get this solved. I will definitely keep posting my progress.

[Coleman El]

So maybe, once I install the new pedal, it will correct the rough idle. You think so?

[andrewwynn]

You need to be able to read data real-time like the pedal and throttle positions.

When my idle was horrible it was from a giant vacuum leak. Car set a code for ICV.

When wife's car acted similarly, it ingested the o-ring from the MAF into the throttle body and jammed the throttle plate.

[Coleman El]

I would love to do that. But my version of INPA is older, so therefore don't have option for e53. Maybe I could use the e38 option since it's the same engine. But, also, when I press the pedal, it doesn't respond or anything.