Tracked 128i - Limp Mode?

[964junkie]

The car is a 2010 N51 128i auto, completely stock except for some suspension and brake modifications. The symptoms are lagging throttle response, rev limit lowered by ~1,500rpm, and full throttle is like half throttle. The problem is usually triggered by negotiating high-g left hand corners at speed, i.e., the left hander at Lime Rock, and turn 9 at Monticello. After taking it easy for a lap or two in top gear, everything returns to normal. No idiot lights illuminate, the dealer did not read any codes related to this.

DSC and DTC are always off, and this happens consistently in the same places, regardless of fuel load.

Anyone have similar issues? This is driving me crazy! What's the solution?

[Jatran661]

Engine temp or oil temp too high would throw it to limp mode for a while.

[AW128i]

Transmission temp might be the issue, also. Weird that there aren't any codes or anything showing the limp mode.

[Greenkirby21]

when I dynoed my 128i, it went into limp mode because the engine temp was too high. Might be that. It doesn't help we don't have oil temps gauges.

[aus]

There was a 128 at Buttonwillow this weekend that seemed to do fine, and it was CRAZY HOT out there.

.

[Guildenstern]

I get this on the OakTree at Nelson Ledges too. which is a slightly banked long tight to medium left hander, both in DSC and DTC mode. No lights or indicators. Car just looses all it's guts, But it's usualy back on full power once I exit, and the decreasing radius right just before the front straight the car has full powe, Could it be some form of oil starvation protection? Is the left hand turn the weak side for the oil pan?

[DriveHard]

Originally Posted by 964junkie

The car is a 2010 N51 128i auto, completely stock except for some suspension and brake modifications. The symptoms are lagging throttle response, rev limit lowered by ~1,500rpm, and full throttle is like half throttle. The problem is usually triggered by negotiating high-g left hand corners at speed, i.e., the left hander at Lime Rock, and turn 9 at Monticello. After taking it easy for a lap or two in top gear, everything returns to normal. No idiot lights illuminate, the dealer did not read any codes related to this.

DSC and DTC are always off, and this happens consistently in the same places, regardless of fuel load.

Anyone have similar issues? This is driving me crazy! What's the solution?

Look at sig>> similar car..

My findings have been that the trans temp is too high.. the car is failsafing into 6th when it does, hence you loose acceleration, i.e. what you call half throttle / throttle lag. the left hander at Lime rock is in 3rd, so you are up there in the rev's espically after flooring it coming out of 2 for that short shute towards the "oak tree" then into turn 3.

I use my water sprayer and spray down the Trans fluid cooler between sessions.. it is located on the drivers side down past the radiator. Its silver with fins on it.. its actually in a poor area, as it gets no direct air flow. I spray it down after i get back to the paddock after checking my tires. I leave the car running and spray it down for a good 5 minutes.. I have seen IR thermometer temp drops of the cooler in the 40 degree range.. ever since i began to do this i no longer have the issue that you speak of...

P.s. The first time i had it was at Lime Rock also... just on the back straight oddly enough. ambient temp, as always makes this issue worse..

p.s.s. i called around.. nobody makes a bigger cooler. It would have to be a custome one off for us 6AT guys..

p.s.s.s. do you paddle shift or you the shifter it self???

[JimD]

I have not done any high speed tracks in my 128 convertible with manual transmission but I've done autocross several times with no issues. It doesn't even get hot enough for the fan to come on. Top speed is about 70mph but lots of corners at speed. Since my manual doesn't have any issue, it would support a AT issue.

Jim

[moveswiftly]

Originally Posted by JimD

I have not done any high speed tracks in my 128 convertible with manual transmission but I've done autocross several times with no issues. It doesn't even get hot enough for the fan to come on. Top speed is about 70mph but lots of corners at speed. Since my manual doesn't have any issue, it would support a AT issue.

Jim

Your argument is flawed man! It could be several other things and autocrossing is nowhere as strenuous as a full 30 minute lap.

It could be an AT issue but it could also be oil temps are going too high.

OP: That's odd that there were no codes, do you use manual on the track or drive sport?