Cranks, won't start w/o jump. RPMs bouncing

[Recklessdr1ver]

Not my video but my car started doing the same thing. Took it to BMW and they told me it was my throttle body. After some research, I saw that throttle body failure caused similar issues so I went ahead and ordered the part. Yesterday I swapped it out but nothing changed. Hopefully someone here has fixed this problem before.

Thanks

[nacaruh]

im not able to watch the video, but maybe it's a dead crankshaft position sensor? i had the same issue awhile back.. it wasn't dead, but faulty, so the car would start, but while idling, it would sometimes stall on me randomly, and some crazy misfires.

[Recklessdr1ver]

No misfires yet. As soon as the engine does start, the needle steadily bounces as the the engine revs itself. CEL, traction, brake and limp mode all come on and when driving, it has no power and can't get above 3000 rpm

[Freon]

You always need to read codes with at least an OBD2 compatible reader when asking for advice with issues with your car. Even if it is just to say you tried with X brand scanner and found no codes, but I very much doubt you have no codes.

Codes can help narrow the issue down from hundreds of possibilities to a handful. A vast majority of trouble codes that cause acute issues spell out exactly which sensors or motors are the problem.

There's no reason to continue troubleshooting without an OBD2 read.

[Recklessdr1ver]

Originally Posted by Freon

You always need to read codes with at least an OBD2 compatible reader when asking for advice with issues with your car. Even if it is just to say you tried with X brand scanner and found no codes, but I very much doubt you have no codes.

Didn't say I didn't have codes. I said I didnt have misfires. I attached 2 crappy photos from my JB4. My gut is telling me its the battery thats screwing everything up but BMW insists that if it cranks then its not.

[Freon]

Looks like p2a9a and p2a9b are VANOS related, probably solenoids since that seems a somewhat common issue.

My guess on the fuel pressure ones are either they are a byproduct of you cranking the engine repeatedly, or in combination with other unrelated codes you have a bad ground which is causing many issues. Have you replaced the battery recently, or done any other work where an engine ground may have been disconnected? Audio equipment installs? Since you seem to crank ok I'm not sure the battery is actually bad, but it is possible. A bad ground in a specific spot where some sensors get their ground seems more likely to me, and I've seen this happen several times on different brand cars. Several sensors that pick up ground from a specific spot with a bad connection will all pop CEL codes.

[Recklessdr1ver]

Originally Posted by Freon

Looks like p2a9a and p2a9b are VANOS related, probably solenoids since that seems a somewhat common issue.

My guess on the fuel pressure ones are either they are a byproduct of you cranking the engine repeatedly, or in combination with other unrelated codes you have a bad ground which is causing many issues. Have you replaced the battery recently, or done any other work where an engine ground may have been disconnected? Audio equipment installs? Since you seem to crank ok I'm not sure the battery is actually bad, but it is possible. A bad ground in a specific spot where some sensors get their ground seems more likely to me, and I've seen this happen several times on different brand cars. Several sensors that pick up ground from a specific spot with a bad connection will all pop CEL codes.

Couple months ago the battery was leaking and instead of replacing it they "topped it off". It seemed to be fine and it's not leaking now. Nothing electrical has been done to the car. Any suggestions on how I can check the grounds?

[loesch]

Interested in the solution. I'd remove the jb4 first just to make sure it isn't something with wiring in the DME box. Plus that's free to try. Don't forget to disconnect the battery first.

[Recklessdr1ver]

Bump

[Dackelone]

I have to ask the obvious... your car does have fuel right>?

Originally Posted by loesch

Interested in the solution. I'd remove the jb4 first just to make sure it isn't something with wiring in the DME box. Plus that's free to try. Don't forget to disconnect the battery first.

+1 on the above.


Maybe try disconnecting the battery for a few minutes and then retrying. Sometimes a low battery can really mess with the car's electronics.

Why not borrow a buddies car to jump start yours? That would eliminate your battery. Just disconnect your neg/ground then use the known "good" battery.

I'm curious as to your problem too.

Dackel

[TUN3D]

Do you have a JB4? Minus the cranking, this exactly what happens when you reset your adaptations. The codes are a bi-product of the car not turning on.

[Recklessdr1ver]

Originally Posted by Dackelone

I have to ask the obvious... your car does have fuel right>?




+1 on the above.


Maybe try disconnecting the battery for a few minutes and then retrying. Sometimes a low battery can really mess with the car's electronics.

Why not borrow a buddies car to jump start yours? That would eliminate your battery. Just disconnect your neg/ground then use the known "good" battery.

I'm curious as to your problem too.

Dackel

Yeah, full tank. When it first happened I was about to park when it stalled in the street. After a few tries it turned over. As soon as I parked it, I disconnected the battery for about 30 mins.

[Recklessdr1ver]

Originally Posted by TUN3D

Do you have a JB4? Minus the cranking, this exactly what happens when you reset your adaptations. The codes are a bi-product of the car not turning on.

I do. Just googled resetting adaptations and I'm going to try the step by step when I get home.

[TUN3D]

Recklessdr1ver > Did you recently install it or updated the software? On Monday, I did a firmware update and hit option 1/7 (reset adaptations). I always do this when I load new updates or get a new blend of gas. Car always goes nuts and doesn't start right away. It does exactly what yours did. Codes go nuts as well.

The only difference is that mine didn't have that long crank. It starts up right away and the RPMS go nuts. After a few tries it goes away. I clear the codes and that's it.

Did it do this before the JB4?

[Recklessdr1ver]

Originally Posted by TUN3D

Recklessdr1ver > Did you recently install it or updated the software? On Monday, I did a firmware update and hit option 1/7 (reset adaptations). I always do this when I load new updates or get a new blend of gas. Car always goes nuts and doesn't start right away. It does exactly what yours did. Codes go nuts as well.

The only difference is that mine didn't have that long crank. It starts up right away and the RPMS go nuts. After a few tries it goes away. I clear the codes and that's it.

Did it do this before the JB4?

No, haven't updated it since I got it a few months back. I saw here another way to reset it,

www.e90post.com/forums/showthread.php?t=841784

, hopefully it works.

[Recklessdr1ver]

Update: So I did the 1/7 option on the JB4. Result, no fix. What I did find out though is that I can get my car to start on it's own if I first push the ignition button before holding down the clutch and then pushing it again as opposed to how I normally start it which it just pushing the clutch then ignition. Next will be to take out my JB4 I guess.

[loesch]

That could be fuel pump related. You're priming the fuel pump by turning the ignition on before starting the car. Still could be electrical too. I'd still definitely try removing the jb4 first.

[Recklessdr1ver]

So I pulled out the JB4 with no luck. Here I went ahead and posted my own video.

Any ideas that I could troubleshoot myself?

[Recklessdr1ver]

Bump for help

[MuNkY6913]

Do you have a thread on n54tech?

[Dackelone]

I think you need to have the throttle limitations set. When I had my SW flash tune installed here in Germany... my car did the same thing. Perhaps since you have replaced your throttle body, you now need to "code" it to the car. Or perhaps you just need to have a dealer set the throttle limits - so the DME knows what the parameters are. ?

I would take/tow the car to the dealer who told you, that your throttle body was bad and have them see what's going on.

I bet you could even have BMW assist come and try to "fix" your car at your house. Might be work calling them up.

Dackel

[loesch]

At least now that the jb4 is out your dealer won't blame that for the problem if you take the car in. I was hoping it would be the wiring with that. The throttle body coding suggestion is interesting. Makes sense. The throttle body vacuum line is in good shape at both ends?