So I don't know if I'm being paranoid/this is all in my mind, but on a short trip over to a friend's house, my 07 mcs seemed to suddenly develop a lot more turbo lag. There's definite hesitation when I floor it in gear and it's between 2-3K rpm at the start of my WOT, usually theres slight lag but this seemed excessive. Drove it earlier today (about 45 degrees F out) and it was fine, then tonight it was slightly above freezing, and the short trip to and back from my friend's house was filled with frustration at this sudden hesitation. Could this be the sign of the turbo going bad or carbon buildup? I woulda thought carbon buildup would be a gradual increase in hesitation not an all of a sudden thing. Thanks for the help guys. BTW only about 42k miles on it.

 

Have you scanned the ECU to see if there are any present fault codes?
Sounds like a misfire hesitation from preliminary details.
Has the high pressure fuel pump (HPFP) ever been replaced on the car?

- Erik

 

Did the car make a deep sound during acceleration, and did it improve after the car warmed up?

 

Was this on the first take off? Sometimes when the car is cold it has lag until it reaches it's temp.

 

Personally I wouldn't even try to get any power out of a car during a short trip. Oil temp lags about 5-10 mins behind the water temp and I never give my car any pedal until it is warm.

I would warm it up and see how it behaves, if it is fine when the oil is hot then it was just the car protecting itself. Cold oil is thick oil that does not do a good job lubricating and protecting. Your car will not run properly when it is cold. It tries it's best to protect itself.

 

I haven't scanned it for codes, and I definitely should look into that. Would the hpfp throw any codes or is it only something a dealer would be able to tell (with certainty) that needs to be replaced?

 

If the pump is failing, the car will point out some related fault codes.
However, there isn't specifically a hard code for the mechanical pump.

Agreed! This is something that is being preached all over NAM with the winter season settling in once again.

- Erik

 

Thank you all for your help. On several longer trips (with 15 minutes of prior warm-up time) the car seems to lag around 2800 rpm, the rpm's suddenly drop off and it hesitates from then on at half or full throttle. So this is just the car protecting itself in the winter? I find it strange that it didn't do this on several colder days earlier this year.

 

the car doesnt protect itself during winter, during colder temps it lower boost levels to provide the same level of power associated with denser charges due to air temps. Describe the lag a bit better, There is also normal acceleration and overboost function acceleration which are dramatically different. You may be experiencing that. As the previous have stated dont give your car requests for power until it is wamred up, the turbo bearings are standard journals which are not the best for smooth operation until the oil temps are up.

 

well to go into more depth.....the car's fully warmed up after sitting for 15 mins prior to traveling and I'm about 25 minutes into my trip, it's around 40 degrees F out (~5 degrees celsius, 278.15 degrees Kelvin) let's say I'm driving at 45mph in 4th gear, i lay the hammer down and it surges forward for a bit, rpms jump like normal then my engine pretty much says "just kidding" as the rpms die off, the acceleration decreases greatly, but it still accelerates, just nowhere near as hard as it was doing a week ago

 

Have you taken a look under the bonnet to see if there are any oil leaks near the turbo area?

 

There are a number of threads around here about this exact subject and NOT to let the car sit to warm up. in fact every one in those threads that has in the past let the car sit to warm up have had a similar problem as you. When they changed their driving habit to just get in the car and drive off (not getting on it to hard though) after a driving warm up have had not such problems.

So rather than start the car and let it sit do what MIN/BMW recommend and drive off right away. I would bet your problem goes away.

 

Yeah I checked under the hood and I didn't see any oil leaks or anything. The oil level checked out fine. I will have to try the non-warm-up method. Thanks again.

 

Possible high pressure boost leak? Mine has done this, cant remember how many times though, only in cold weather but not to the severity of this incident. I dont let the car warm up per say but I do let the car idle for the 1-2 minutes it takes the idle to settle down to normal and I never get on it when its cold.

 

OK,
We'll keep trying...

 

I had a similar issue a few weeks ago. Then last week the same "lag" happened and the check engine light clicked on for 2-3 seconds then back off. This weekend check engine light came on and has stayed on, took it to Autozone to have them do a diagnostic. The computer returned codes for "random misfire cylinder 2" & "random misfire cylinder 4". Also having a slight tick when accelerating at low RPM(<3,000), foot off the pedal=no tick, not sure if the ticking continues at higher RPMs as the motor drowns it out. No leaks and fluids are at the right level. BTW its an '08 S w/55 K and I live in CT so the cold may be a factor. Advice???

 

Bad or low quality gas perhaps?

 

I'm about a 1/4 of the way through a fresh tank that I put fuel treatment in. Also decided to bite the bullet and scheduled an appointment with Mini next week.

 

Keep us updated. I'm in CT too and been having some funny boost behaviors in this recent weather. A lot of it has to do with the varying temps too, its been crazy. 6*F this morning. Car does adjust for temps with boost to hit target power levels. I've also seen the random misfire codes from pending codes. It could be the HPFP, coils, spark plugs, boost leak, diverter valve, is all possible. I've been having a weird stumbling on cold starts for the first 10-20 seconds, which i think is attributed to the hpfp and which caused a pending misfire momentarily. Otherwise, its doing OK and drives fine. I have some slight hesitations as well in the cold when boost comes on. I think its related to the cold temps, as it hits about 3psi higher in 45*F+. Its about time for another seafoam anyways. The water/methanol is only doing so much for maintaining the levels of carbon I'm at, but definitely have plenty of build up from before installing w/m.

 

Car went in at New Country Mini today. They found codes for bad timing, poor spark, and thermostat for the cabin. Thermostat isnt really a part of the problem. They said I'm looking at a full timing chain kit (about $1500)and new plugs to fix the problem. Good to know the problem and glad I caught it before it was fatal but this still sucks... I contacted MINI USA to see if they will help with the timinig chain fix and will hear back from them in 1-3 days.

 

yeah,
I heard there's a service bulletin about the timing chain too.

 

Is it possible that this is a clutch related problem? Could it be slipping when I give it hard throttle around 2500 rpm? There's also a noise- definitely clutch related- that comes from the car as I'm starting off, if I don't start off really slowly theres a definite noise probably coming from the clutch as I take off in first.

 

Signs of a slipping clutch are a jump in rpms under high load (usually more obvious in higher gears) along with no acceleration.

If you think it's slipping, start the car, apply the handbrake. Put it into 3rd or 4th gear. Slowly let up the clutch. If you stall it right away, the clutch is in good condition. If the rpms start to fall and the engine doesn't cut out, it's a pretty good indication the clutch is slipping.

What is the clutch noise you are talking about - can you describe it?

 

Well I did the test, and it unfortunately didn't die, the rpms just surged repeatedly. Guess I will need a new clutch soon...great. The sound is like a high pitched squeal, like a metal on metal grinding. Again, not good.

 

If you want my advice, if the clutch is slipping as you describe, I would get the car serviced now rather than later. Waiting will only cause more damage. With the degree of slipping you describe, I think you'll also have to replace the flywheel.

If you're not concerned about the warranty too much, I suggest getting the clutch changed at an independent garage, rather than the BMW/Mini dealership. An independent will be considerably cheaper (although still expensive), but you won't have the same guarantee coverage.

When I had my clutch changed, the cost was approximately €1800 at the dealership (a large part of this was labour charges). Also, after you get it changed, break the new one in very, very gently.