MoTeC Global Forum

Hi guys,
My car is on M600 was perfectly fine If i dont connect the vaccum line thru the intake manifold to the brake booster. Drove the car that way for few days only to realize thats the quickest way to wreck the car in Mid East, drivers just dont care who's on the road so gave up and sent a line to the brake booster.

Now, the question. This causes car to behave like its misfiring but all the coils are working properly, its running rich fo suuuure! There is also now a behavioral pattern like a car does when it has boost leak ( its a boosted car) but zeroing it down, its only because I am running a booster now. So whats the workaround?
1. Add correction to the air/fuel mixture after making sure everything is perfect mechanically.
2. No longer run the car on brake booster.
3. Add more boost.
4. Something to do with wastegate spring pressure adjustment?
Or something else. Also note i have run boost controller from hks, just wanted to put that here.
Turbo: Garrett GT38 something with A/r 0.7
Engine: RB25DET

I think you need a check valve in your vacuum line going to the brake booster. If you want the brakes to operate more than once when on boost (ie. if you left foot brake), then you may need to add a vacuum reservoir.

It seems obvious that you've got a boost leak. Perhaps the brake booster or some piece of the plumbing has failed. I would try to find that.

Thank you david, I shall zero in on the problem as soon as i find the time.