[iCstyle]

Hi!

I got a E92 335i, N54, DCT, JB4, with about 25'000 miles.

I'm encountering a problem. When activating cruise control on highway at a slight hill, it sometimes gets me 30ff error with engine fault warning. It has done this also on map 4, but not yet on map 0. After decreasing menu 10 to 3000 rpm and menu 12 to 2000 rpm, it hasn't happened again while testing.

I activated underboost/overboost on oil gauge, and I see that when activating cruise control, it goes for a sec to max. overboost sometimes. While accelerating myself low, overboost goes just maybe 1 notch to the right.

I also noticed that when activating cruise control, it's like it gives too much throttle for a sec (in this moment the overboost needle goes to max), and then recudes throttle to 0 and accelerated smoothly (overboost needle in the middle). It has done this also before without JB4.

What could be the problem? HPFP? Boost leak? Trans slipping?

Thanks!

[Jeff@TopGearSolutions]

30FF would indicate underboost and likely a boost leak.

It makes sense that this doesn't happen on Map 0 as there is less boost and thus easier to hit boost targets with a small leak.

Unfortunately, boost leaks can vary from multiple locations.

It's best to get under the hood and inspect vac/boost lines, chage pipe and intercooler connections.

Although things may appear secure at first glance, hair line fractures and cracks in rubber or expansion of clamps under pressure can make the difference between a boost leak and a leak free connection.

If you have any aftermarket intercooler charge pipe and or BOV I'd start at those locations first.

There are many vac.boost lines running under the engine cover as well all the way to the turbo's.

[iCstyle]

Thanks, I'll check them.

Car is else everything stock.

What about the overboost going to max. while activating cruise control? And why does 30FF only appear while activating cruise control, and didn't ever while doing WOT on Map 5?