[stieny]

I know this topic has been discussed a million times but after reading a ton of threads, I can't find anything specific relating to what I've just noticed...

Car specs: '11 335i w/ PPK1 at just under 45k....

Driving home from work yesterday, on the highway at about 65-70, I dropped down to 4th gear and started to easily roll on the throttle. I had my music up at the time so I wasn't paying attention but the car definitely didn't accelerate like normal. Having been around cars all my life and having several manuals, it immediately felt like clutch slip but without listening or paying attention, it was tough to tell.

I did a couple more pulls, switched gears a few times, and varied my speed but I couldn't replicate it again on the way home.

So this morning I'm driving to work and I noticed the same thing....6th gear at about 75-80. I roll on the throttle and nothing for a second or two and then the power comes on. Switch to 5th and 4th and I can replicate the same thing, just not consistently. The revs don't really rise like clutch slip, and if they do, it's very minimal for those few seconds matched with very slow acceleration, if any....and then the power comes on. It feels like a delay from the CDV.

My question is, why all of a sudden am I noticing this? Are these prone to failure? Out of all the CDV threads I've read, I haven't come across any that mention the CDV going bad. Probably because most take them out. The car shifts smooth and holds power when you're WOT through the gears. I've never had any issues with it.

The car is due For its 45k service soon but I wanted to see what others thought before it goes in and before its out of warranty.....clutch slip, bad CDV, or normal CDV action?

[Douche]

None.

My bet is your injectors are leaking.

[MiniXP]

I don't think this has anything to do with the cdv.

Maybe your spark plugs could use replacing (I just say this first bc it's the cheapest)? Sounds like it is just bad throttle response.

[ccraig13]

I had my clutch replaced (disc + fly wheel) last year. This past month I noticed some sporadic slippage. Each time it occurred, the car had been parked for a long period of time in 30-40 degree weather and it would happen within the first 5min of driving. It was more of a stutter than the slip I was having before I replaced it. Like as I would accelerate (2k RPM to 3k RPM) it loose then regain grip about 3 times before finally sticking. After that initial slip I'm unable to reproduce. Happened about 4 times in the past two months.

[weehe126]

Originally Posted by Douche

None.

My bet is your injectors are leaking.

He has an N55, it is not a leaky injector. I agree it is probanly plugs. If you have ppk then I think they are supposed to be replaced at 40k miles. So they will probably do that when you go in.

[Douche]

Originally Posted by weehe126

He has an N55, it is not a leaky injector. I agree it is probanly plugs. If you have ppk then I think they are supposed to be replaced at 40k miles. So they will probably do that when you go in.

Oh I'm sorry. I don't know enough about the N55, I thought they also had fuel injectors.

My apologies.

[PhaseP]

If you are not seeing rising revs with no increase in speed, it is not your clutch slipping, and so not related to your clutch, and so not related to your CDV.

[PhaseP]

Originally Posted by ccraig13

I had my clutch replaced (disc + fly wheel) last year. This past month I noticed some sporadic slippage. Each time it occurred, the car had been parked for a long period of time in 30-40 degree weather and it would happen within the first 5min of driving. It was more of a stutter than the slip I was having before I replaced it. Like as I would accelerate (2k RPM to 3k RPM) it loose then regain grip about 3 times before finally sticking. After that initial slip I'm unable to reproduce. Happened about 4 times in the past two months.

OEM or aftermarket parts? Just curious.
What you are describing kind of reminds me of a Miata I had owned. For a certain production range they had used a clutch lining material that wasn't matching very well with the flywheel in use. Especially damp mornings, it used to stutter during clutch engagements a few times, then clear itself. It is probably some rust developing on the flywheel surface during parked due to humid weather. Then after one or two clutch slips or engagements this gets cleared up. When clutch lining material is good match to flywheel, this gets cleared up immediately, from what I heard.

Haven't seen any of this with the E90 or other manuals I drove. That is why I asked aftermarket parts or not.

[stewey]

If it's happening in high gears but not low gears and you are getting a subtle rise in RPM, then it's probably time for a new clutch. this is how a failing clutch typically presents itself.

To test it, put the car in 5th or 6th at ~2000 rpm and punch the gas. Watch the tach. If it flares up, that's slippage.

[atinybug]

The CDV is not a part that can "fail". Unless it just completely comes apart and then you'll definitely know something's wrong. It basically is just a narrower section of the clutch lines that force the fluid to move through it slower. There's no moving parts that wear out or break in it.

[weehe126]

Originally Posted by Douche

Oh I'm sorry. I don't know enough about the N55, I thought they also had fuel injectors.

My apologies.

Please link to me any instances of N55s having leaky fuel injectors. If you were just saying that knowing it was a useless guess I guess I should tell him the problem is occuring due to his floor mats being the wrong style.

[924er]

Originally Posted by weehe126

He has an N55, it is not a leaky injector. I agree it is probanly plugs. If you have ppk then I think they are supposed to be replaced at 40k miles. So they will probably do that when you go in.

Are the n55 injectors different ?

[stieny]

I appreciate all the comments guys.

I don't know how a leaking injector would cause that. From what I've read, a leaking injector causes rough idles and poor cold running conditions. Not saying it couldn't be, I just don't see that likely.

I just took it out on my lunch break and I'm fairly certain it is not the clutch. Regardless of where I pull in the rev rage, it always pulls. I tried 1800 in 3rd, 2300 in 4th and a few other scenarios of lugging it down, it always pulled.

On my way back to work, I was able to reproduce the symptom by rolling on the throttle in any gear but it would only do it every 4-5 times I attempted it. It almost seems as if there is a delay with the pedal input via the drive-by-wire or the car is intentionally not boosting for those few seconds. After the delay, the power comes on full and smooth.

But then I got back to work and noticed this....I'm not sure if it's related or not. Could it be a water pump going bad causing the computer to cut boost?

[weehe126]

Originally Posted by 924er

Are the n55 injectors different ?

Yes, they are different than the known to be leaky N54 injectors.

[Sambonjo]

Originally Posted by stieny

On my way back to work, I was able to reproduce the symptom by rolling on the throttle in any gear but it would only do it every 4-5 times I attempted it. It almost seems as if there is a delay with the pedal input via the drive-by-wire or the car is intentionally not boosting for those few seconds. After the delay, the power comes on full and smooth.

I felt something very similar a week ago. Felt like no boost coming on for the first few seconds and then it would boost normal. Hasn't happened in a few days. I'll see if I can replicate it again. Not sure what could be causing it.

[stieny]

Well, an update....I must have been feeling a limp mode.

On my way home, the car was doing it more and more often. By the time I hit my street, the fans were on full blast. 3 blocks from my house, I get the orange warning and the car running hot message. A block from my house, I get the red warning and the shut down message. By this time, my car is in full limp mode. I pulled into my driveway and shut it down. Now I'm waiting on the tow truck to take it over to the dealer.

[ccraig13]

Originally Posted by PhaseP

OEM or aftermarket parts? Just curious.
What you are describing kind of reminds me of a Miata I had owned. For a certain production range they had used a clutch lining material that wasn't matching very well with the flywheel in use. Especially damp mornings, it used to stutter during clutch engagements a few times, then clear itself. It is probably some rust developing on the flywheel surface during parked due to humid weather. Then after one or two clutch slips or engagements this gets cleared up. When clutch lining material is good match to flywheel, this gets cleared up immediately, from what I heard.

Haven't seen any of this with the E90 or other manuals I drove. That is why I asked aftermarket parts or not.

The parts are OEM but I think the fly wheel is not the BMW branded version, just one from LUK directly.

[W.WCherry]

Originally Posted by 924er

Are the n55 injectors different ?

N54: Piezo injector by Siemens
N55: HDEV5 injector by Bosch

[924er]

Originally Posted by B.Corso

N54: Piezo injector by Siemens
N55: HDEV5 injector by Bosch

Right. Thanks for the clarity.

The Siemens injector was the old one no? I don't think BMW has been using those anymore. The last time I replaced my injectors I got the bosch for my n54

[MiniXP]

Originally Posted by 924er

Right. Thanks for the clarity.

The Siemens injector was the old one no? I don't think BMW has been using those anymore. The last time I replaced my injectors I got the bosch for my n54

The whole fuel injection system on the n55 is different I believe. It's more than just a matter of updated injectors.

[924er]

Originally Posted by MiniXP

The whole fuel injection system on the n55 is different I believe. It's more than just a matter of updated injectors.

I would think so. But as far as injectors I think the n55 and n54 share the same maker currently . I know the HPFP is the same