Turbo boost low, with tcv AND mbc, but high without??

afmattgto · Post by **afmattgto** » 14 Oct 2010, 21:57

2002 C70 coupe.

So the C70 is low on boost. Its pushing about 3-4 psi. Usually around 11psi. All the turbo hoses are ok. I disconnected the TCV and let the wastegate hose hang free, and pushed 15psi or more..oooops lol... I hooked up my manual boost controller (made by me) just to see...and it only boosts at 3-4 psi, no matter how I adjusted it.

What would that be? Could the vacuum line from the compressor side be messed up causing it to only push 3-4 psi?
It did throw the P0442 code... which ended up being the j hose on the back by the shut off valve, had a crack in it.

I got a bunch of vacuum line ready to go on, and tommorow Ill be changing alot of them! And going to run a line from the intake to the side of the tcv just to see if it will do anything.

Any ideas?????????

afmattgto · Post by **afmattgto** » 15 Oct 2010, 06:17

no ideas?? nobody has had this problem? I couldnt find this same issue in the threads here so figured I'd ask. On to changing all the lines lol!

Post by **jblackburn** » 15 Oct 2010, 08:57

It does sound like a vacuum line issue to me. I'd change all 3 of them.

Boosting that high (15 psi) is a lot of fun...until your car gets mad and slams into the fuel cut

I'm going to move this to the 2001 and newer section btw, in case you want to find it later. Let us know what you find out, or if you're still having issues after changing vac. lines.

afmattgto · Post by **afmattgto** » 15 Oct 2010, 20:57

well...changed all 3 from the turbo...changed a few other ones too... doing the same thing... going to run a different line for the TCV from the intake tommorow and see if it does anything ... had a friend stop by with some Red Stripe that he needed help emptying.. couldnt let a friend down!!! Pushing Air through the Bypass connection on the turbo lets air through? Is that normal?

Also, the two check valves for the evap lines?? How do they route? Got a line from the intake manifold, going to a T fitting, then a line from the T to the intlet line, and a line from the T to the evap solenoid or whatever it is on the radiator shroud. Ive got an idea of how they route (which way the arrow points) but Im not sure?