Please Help - E93 M3

[psword]

Hi All, newbie to the forum, but hoping I can get some help from you all that know a hell of a lot more about BMW's than me. Please bear with me as I try to give as much detail as possible. Please also bear in mind that while I love driving good cars, I am not mechanically minded at all, so if I sound stupid, its coz I am!

So I had to put my '10 E93 M3 DCT into the shop last week due to an engine light coming on, limp mode engaged, and error code indicating Brake booster error. Shop ordered the part, fitted it, and said it was ready to pick up. As I drove away from the shop, no issues, but about 20 mins later, when the car was warm, I started noticing some very strange happenings. As I slowed to a slow speed and low revs, if I tried to accelerate, virtually nothing would happen until the revs reached approx 3,000, then power application seemed normal. The problem was, it took an eternity to reach 3,000 rpm. I would plant my foot flat to the floor, no difference. It was a though limp mode was engaged to 3,000 rpm. I then stopped the car and tried to accelerate from stop. It would lurch forward as if normal pull away, but then rapidly retard acceleration and rpm, and back to the slow rpm increase as before till it reached 3,000 rpm then normal, just like before. This happened almost without exception.

I called the shop and he said it sounds like a slipping clutch. Like I said, I am by no means an expert, but I though a slipping clutch normally results in rapidy rising revs without the corresponding increase in speed? is this different for a DCT clutch? It also seems a little too co-incidental that there was absolutely no indication of clutch slip before the brake booster problem, but as soon as it comes out of the shop, the clutch begins to slip. It is possible for sure, but a VERY big co-incidence. That makes me think something else may be in play here

The slipping clutch doesn't make a lot of sense to me. So I seek any helpful advice from you guys. Any suggestions as to what it might be? I did read about the VANOS on this forum, similar symptoms, but seems to be mainly on the E46, not so much the S65 engine found in the E93.

Any help is greatly appreciated.

[hlmiii]

This won't provide much help, but I've had similar situations with E46, 135 and E90 models. Virtually identical performance and symptoms.

In NO instance were there ANY considerations involving the manual or automatic or DTC clutch hardware or software. So, I don't think that would be the issue.

FWIW -
E46 - coil and/or plug problem
135 - HPFP hardware and software
E90 - fuel delivery

Good luck.

[psword]

Thanks hlmiii, I will look into all of those

[mazing M3]

I would also look into the drive by system since our cars throttle response is computer control no more wires directly attach to the throttle bodies anymore.

[hlmiii]

Note that your ride won't have the turbo-based HPFP issue. I was just mentioning that as example of having same symptoms that is not clutch-related.

Bottom line - there are a LOT of electronic and sensor and other technical items with this and other contemporary cars that can go screwy and result in symptoms that seem to be the same as the traditional symptoms - clutch response, in this example - in older cars.

Suggestion: do some research on your own here and in other forums so that you have a working baseline understanding of general operations and issues with the E9x generation (it'll only take a long, enjoyable weekend). You need to have this so that you have a feel for the "rightness" of early responses and diagnostics from service people. It'll save much time, money and frustration - you will provide an initial credible starting point for both you AND the service people.

[psword]

Thanks for that hlmiii. I do understand what you are getting at regarding the complexities of the cars these days. As I mentioned, the clutch slippage just didn't and still doesn't make sense to me. I have been doing a lot of reading today, and conducted another lengthy test drive today to confirm and re-confirm what happens under varying speeds, rpms, loads, acceleration rates, throttle positions etc. Will check back after I take it back in.

[hlmiii]

Good luck.

[mjposner]

Get a bluetooth obd 2 plug and an app called torque and run for codes. The issue sounds ignition related not clutch at all. Was the shop and indie shop? Do they have the BMW computer?

[psword]

Hi Mj, not too sure what computer they have, that is one thing I am going to check when I go in tomorrow. I will be standing beside the technician when they run for codes.

[mjposner]

See if they have the GT-1 system. Only way to really scan. Dealer and high end BMW shops have these.

[psword]

Problem has been solved. As I suspected, and those that have contributed here in the thread also believed, it was indeed not a problem with the clutch. When they replaced the brake booster, they failed to test or adjust the sensor switch on the brake pedal. Consequently, the car believed the brake was permanently "on". The brake lights were illuminated, something I obviously missed while test driving. Also made sense as the cruise control would not engage, somethiing I only realised while taking the car to the garage. When we ran the diagnostics, the DSC showed the error. 2 mins to adjust the switch and problem solved. A lack of quality control at the original garage, needless to say, I won't be going back there in a hurry.

A big thanks to all those that contributed. I hope this thread will help anyone with a similar issue in the future. Sometimes its the really simple things!!

[crypticc]

I wouldn't rule out a garage over a misplaced switch provided they fess up and fix it rapidly and without debate.

While there is a concern I'd they tested the install, at least here you know there is absolutely no way was your car taken for a lengthy joy ride.

A different garage might catch this in their quality control which could involve several high speed drives "just to test the brakes".