The infamous acceleration shudder.

[soocom1]

OK. So I purchased a week ago an '07 335i.

Four days ago I hit the gas peddle to pass someone on a hill and suddenly the car started to shudder like being in 5th gear but doing 20.

The shudder does not go away until I restart the car.


What I have also noticed is that if I accelerate slowly, no shudder occurs unless 1: I hit something over 90 mph, or 2: if I hit the gas while passing someone.
No codes are being thrown, and moreover, I am not finding anything that would indicate any other mechanical problem.

Such shudders usually mean a trans. is about to die, but because it resets after startup, that tells me its computer related somehow.

I have read many different posts on this, but no one common theme.

Ideas?

[beshannon]

My 2009 550 used to do this.

I chalked it up to an undocumented feature.

[Critter7r]

If we're just throwing out WAGs, the intake valves are dirty.

[BimmerBreaker]

no shudder occurs unless 1: I hit something over 90 mph

I get the feeling hitting something at this speed is a recipe for disaster.

[auaq]

07 335i eh? A possibly bad HPFP?

[soocom1]

All of the above is something that I have considered, but one thing still stands out..
It resets after restarting the car.

A fuel pump me thinks would prob. die.

I finally got the SES and need to find somewhere to pull codes that wont charge me $150 for the privilege.

[ALEX 540i]

Most likely just an ignition coil.

[ptarditi]

If we're just throwing out WAGs, the intake valves are dirty.

+1, You can take it somewhere and "read the codes", but I'm not sure how many indies have a diagnostic system that will run a misfire detection test plan that can lead to the carbon build-up conclusion. BMW's newer versions of ista/d can pinpoint the problem, but that engine with that mileage and symptoms of self-clearing on restart is typical of "coking".

[soocom1]

[QUOTE=ptarditi;28179387]+1, You can take it somewhere and "read the codes", but I'm not sure how many indies have a diagnostic system that will run a misfire detection test plan that can lead to the carbon build-up conclusion. BMW's newer versions of ista/d can pinpoint the problem, but that engine with that mileage and symptoms of self-clearing on restart is typical of "coking".[/QUOTE]

In English... lol


Remember, I know Chevy terminology, I am still learning Bimmer speak.

[BimmerBreaker]

I've been around BMWs for years and never heard that term.

[Critter7r]

"coking" is another way of describing the carbon buildup on the valves.

[auaq]

I have heard of this term once by someone and it does mean carbon build up on the valves.

[soocom1]

Ok... So explain to me how carbon build up causes a resettable problem with the engine...

[soocom1]

Ok. Dropped the car off to fulfill a recall on the airbag sensor. The service advisor tells me that two years ago the car had a code 33 fault.. the turbo waste gates. The extended warrantee expired (130k miles) and poss. Repairs of over $4k. Just charming.

[BimmerBreaker]

Well that reaffirms my fear of getting into a turbo BMW out of warranty

Probably wont dissuade me from getting a 135i once they touch the $10k mark but still...

I'd advise going to an indy mechanic, just FWIW!

[Critter7r]

Ok. Dropped the car off to fulfill a recall on the airbag sensor. The service advisor tells me that two years ago the car had a code 33 fault.. the turbo waste gates. The extended warrantee expired (130k miles) and poss. Repairs of over $4k. Just charming.

There's no such thing as a "code 33" fault in BMW testers. They're 4 digit codes.

[soocom1]

There's no such thing as a "code 33" fault in BMW testers. They're 4 digit codes.

What was explained to me was that the car was brought into the service bay in 2012.
There they worked some aspect on it and there was a trouble code explaining that the waste gate may be out. They cleared it out and it apparently ran for another 30K+ miles before I got it. It was after a strong acceleration up a hill that the SES light came on.
The service guy told me this am that the code then was something.. and I thought I had heard 33. Regardless, they cleared the code for the recall and told me to keep an eye on the light to see if it comes on again.

I purchased a Bluetooth adapter and downloaded Torque. With that at least it will point me in A direction to at least start a diagnostic. Once I find out what they are, well move forward.

If it is the Turbos, I may have a very big problem on my hands.

[mhunter29928]

If we're just throwing out WAGs, the intake valves are dirty.

Yeah, I saw this thread last week and thought the same. Also thought maybe injector or coil...

OP, how many miles on vehicle? If over 70k, the valves definitely need to be cleaned.

[Critter7r]

Do the turbos make the clanking noise during decel?

[soocom1]

Negative on turbos.

130k miles.

[Critter7r]

No clanking means the wastegates should be ok. The turbos may still be toast due to oil starvation and/or bearing failure, though.

[soocom1]

No clanking means the wastegates should be ok. The turbos may still be toast due to oil starvation and/or bearing failure, though.

No lag and def. no whining sound. I have driven a car with bad turbos before, and they would be consistent in the shutter. Right now no codes and no shudder. In fact the car is running quite smooth.

[Critter7r]

Ok... So explain to me how carbon build up causes a resettable problem with the engine...

The computer can shut down the fuel injectors of specific cylinders if it notes misfires or excessive knocking that might cause damage to the engine. Then when the car is restarted, the injectors work normally until the condition is noted again.

[soocom1]

Got a P0303 code for No.3.

Checked the O2 sensor readings and see nothing there of note. Vacuum and all other items seem within tolerances so me thinks that given the reset aspect that I have either a dirty spark plug or a bad coil...

What would people think on this? and the best route for checking both?

[Critter7r]

misfire cylinder 3 could be caused by many things, but a vacuum leak probably isn't one of them. You'll want to start your search with items that affect only cylinder 3. Swap the coil with cylinder 1 and the spark plug with cylinder 2. Drive it and retest. if the fault stays, then it's the injector or some other mechanical issue with they cylinder (like something in the valve train), if the misfire moves to cylinder 1 or 2, then you have your culprit.