I have a problem with my 535d, it keeps on going into limp home mode, it only does it when you accerate hard from say 30 to 80 mph, once it 80 or so, it trips into a limp mode, no warning lights.

if I stop the car, turn off engine, start back up again, the cars back to normal, works great, it only does it now and again, maybe once every couple of days, when you have your foot hard to the floor for more than 20secs+, from 30 - 80mph.

Ive had into bmw, they said there was 6 fault codes, and same code which was "boost pressure", so they have changed the boost control soloid, but the car still does it, all the turbo and intercooler pipes were checked.

anyone have any ideas what could cause a boost pressure problem?

cheers

dave

 

There are a series of 4mm ID hoses that control the wastegates and the valve that distributes the exhaust gases between the small and large turbos. One my 3 year old the hoses are age hardened and probably ought to be replaced. Any idea if they checked those?

 

yeah they were checked, I checked them my self aswell

cheers

dave

 

Sounds to me like it could be over-boosting - and apart from the electronic management that only the dealer can check, I'd be looking to see that the mechanical wastegate actuators are not sticking shut. As boost climbs past the preset engine management's 'safe' limits, the engine management would then be playing safe and shutting down - if not, it'll simply burst the rubber intake pipes before it wrecks the engine, and all that boost would be wasted. Then i'd expect it to smoke like a bastard and not have any 'go' as it'll get too much fuel and not enough air. It'll go like hell, too, for a brief moment. Just a thought - I could be wrong of course....