Engine idles rough and then dies.

[Chesty Bonds]

Hey guys,

My mum's 2002 E46 325i manual has been a bit temperamental of late. Had new accelerator softaware installed at BMW Melbourne after acceleration had massive hesitation issues. This was okay for a few days before the car reverted back to its naughty ways.

My dad and I took it back to BMW and told them to fix it. They said the car was absolutely fine. The old man cracked the sads but they refused to budge. I think it has a lot to do with the CDV fitted to our car which, coupled with the fly by wire technology, makes the car terribly hard to drive smoothly.

Then yesterday I get in and start the car and the engine is revving wildly between 500 and 2,000 RPM. Application of the throttle has absolutely no effect whatsoever on the engine revs. After about 30 seconds of this behaviour the engine cuts out. Very strange indeed. Since it's just after Christmas, BMW roadside assist isn't back on 'till Wednesday so we have a lame puppy in the garage.

I think it must have something to do with the ECU and perhaps also the accelerator software. This latest episode confirms for me that the new BMWs are just too computerized for their own good. Ever since the introduction of the fly by wire and such silly additions as the CDV the cars have become unreliable and detached. We want to remove the CDV too because we feel it's blasphemous that you can't drive a BMW hard in the way that it should be designed.

Any of you guys have similar problems with the wildly varying idle revs? This last occurence really is strange! Any thoughts as to what it might be??

Cheers.

 

[bmwhighrolla]

lookfor a vaccume leak is check engine on?? sounds to me like the cant breath try disconnectin the air box there might be a clog or u need a new air filter

 

[Chesty Bonds]

lookfor a vaccume leak is check engine on?? sounds to me like the cant breath try disconnectin the air box there might be a clog or u need a new air filter

Yeah it's highly unlikely that this is the case. We had a full inspection done on the car about 1,000km ago... I think it has something to do with the engine management so I'm wondering if anyone else has experienced a similar problem. It really is weird what the car's doing; my dad has never encountered anything like this before, and he's an engineer!

 

[JGM3E3632]

Sometimes the E46 with go into what is called "limp home mode" Where the ECU makes the engine surge at idle and rev back and forth. I believe that it limits the rpm to 2,000,but I'm not sure on the limit in this mode. Also BMW has a problem from 2001 to 2004 with their coils in the 2.5 and 3.0 Liter engines. They should replace the coils under warranty. Ask the dealer about these two problems. Good luck. keep us updated!!

 

[Chesty Bonds]

Thanks Jared. I'll let you know what ends up happening. All i can say is I would not want to be the service manager who has to talk to my dad at the dealership today

 

[Nde]

I had a similar problem with my other car (MB, not BMW). The service advisor just said its fine. I finally tape my video camera on my dashboard and record entire problem.

Play the tape at the dealership and have them explain to me what that is. After showing them the tape, they finally fix my problem.

Good luck.

My bimmer is in the shop with engine problem. Don't know what the problem is. I hope they fixes it.

 

[Chesty Bonds]

OK just got the car back from BMW. Turns out that the wiring loom which relays the accelerator's position to the ECU was shorted! Can you believe that? This is why prodding the accelerator made not one shred of difference.

The whole dash was removed and a new loom was installed under warranty, thank God. Looks like the job ran into the thousands of dollars. IMO, an actual throttle cable would've been more effective but you can't stop "progress" can you.