Mike951

'86 951 - For those who have seen my other posts, you already know my prolem. For others, I;m getting no boost in 1st, 2nd, and minimal in 3rd, 11 psi in 4th & 5th.

I drove the car today and when trying to get on boost in 1st, 2nd, and 3rd I wold hear what I assume to be the turbo spooling, but there is no boost. The spooling sound can be easily heard, and it sounds very jet engine-ish. How loud are the turbo's on our cars stock? From what I described, doeas it sound like some kind of leak? Weird because I am gettign boost in 4th and 5th.



Thanks
Mike

cpt_koolbeenz

https://rennlist.com/forums/showthre...threadid=80821

Did you try the wastegate checks? How is your exhaust volume?

Mike951

Haven;t done WG check yet, just trying to see what can be determined by sounds/symptms. What do you mean by exhaust volume?

I'll check out that thread

Thanks
Mike

Mike951

I read that thread, hopefully its not the turbo.

Anyone else have any ideas?

Thanks
Mike

cpt_koolbeenz

Do the wastegate checks. Feel to see if your exhaust volume is lower than normal. Maybe your cat is plugged...

Mike951

If I am still getting boost in 4th and 5th, would that rule out the cat, or not necessarily?

Mike

Mike951

bump

Bill

Do you have an electronic boost controller? If so check the settings.

Things to consider,

The exhaust spins the turbo:

1. A restriction in the exhaust system (cat, muffler, crushed pipe) can limit the speed/boost of the turbo.
2. A block in the intake (air filter, dirty intercooler, vacuum/boost leak) can limit the exhaust flow. See item 1. above
3. A broken impeller blade on the turbo can limit boost.
4. A bad bearing in the turbo can limit boost.

The waste gate limits the amount of exhaust the turbo gets:

5. Bad waste gate (weak spring, binding spring/valve) can limit boost.
6. Bad waste gate diaphram can cause overboost.

The cycling valve controls the waste gate via the KLR (stock):

7. Bad signal (leaking vacuum lines) to the waste gate/cycling valve/KLR, can cause overboost.
8. Bad chip in the motronics can fool the KLR (overboost/underboost).
9. Bad KLR can cause under/overboost.


Brief over view of the turbo system. Understand the system operation and then troubleshoot.

Mike951

Nope, no EBC, reliaboost, boost enhancer. Stock.

v944god

Damn Mike I feel bad for you. It's been like this for awhile.

I'm suprised no one has had the same problem.

adrial

Do the wastegate test...

If that checks out OK, I would go through looking for intake leaks.

When the engine is warm and idling, where does the factory boost gauge read? (Even better if you have an aftermarket boost/vac gauge)

Mike951

My autometer reads 18 in vac, IIRC, I'll have to double check that.

Thanks
Mike

Mike951

Adrial, where along the path should you clamp the line, and with what?

Thanks
Mike

Ben Z.

I would think you could clamp it anywhere from the cycling valve to the wastegate. They have pliers designed for that. Or maybe you could just disconect the hose from the cv to the wastegate.

Mike951

Anyone know anything about these special pliers, or what I can use for a substitute?

Thanks
Mike