Pulsating Turbo Gage Readings

jzmuda · Post by **jzmuda** » 27 Apr 2009, 13:45

Hi,

I recently purchased a 1994 850 Turbo that was running pretty rough and the turbo was not building boost.

I recently replaced my PCV system and in the process replaced several bad vacuum connections and a split intercooler hose.

The car runs better now (although still not as smooth as my other 850 Turbo), but I noticed that the boost pulsates. It generates boost, and then the pressure falls off a bit, but then builds again to surpass the level at which it originally began to fall off . . . it then falls off again . . .

This process continues through redline.

Any ideas?

Thanks,

Jay

Post by **MadeInJapan** » 27 Apr 2009, 13:51

It's not doing that in sync with gear changes? If not then I would say you have some slight vacuum leaks or maybe even turbo pipe leaks.

jzmuda · Post by **jzmuda** » 27 Apr 2009, 14:21

No, it is not in sync with the gear changes. I have sprayed starting fluid around all the vac lines and turbo piping. Is there another way to find leaks?

Thanks,

Jay

Post by **MadeInJapan** » 27 Apr 2009, 14:38

Probably not going to find them at idle due to this happening at boost...I would just go through everything and tighten things down accordingly. Have you chipped your computer and getting more than stock boost? If so, I highly recommend you go to silicone hoses and T-clamps. Anyway, post back and we'll try to figure this out. Oh, and it could be that since you replaced some things and did some work on your car (intake came off?), you need to reset your adaptives by pulling the car battery's negative cable for a few minutes and step on your brake pedal while everything's off. Also, just a note that it will take a few days of driving for the intake manifold to seal up properly after switching out the gasket...at least that's been my experience.

jzmuda · Post by **jzmuda** » 02 May 2009, 09:55

I have reset the computer (the battery was disconnected during the duration of the project and I pushed the car in and out of the garage a few times, using the brake to stop).

I have not chipped the engine.

I've driven it a few days now and things have not improved (the intake manifold gasket thing sounded like a good culprit to me).

Is there a place where I can pressurize the system to observe the bleed down?

Thanks,

Jay