bonus12

Hi, I've got an 86 Turbo with Autothority Stage II Chips and a banjo bolt restrictor. It's pretty stock overall. The car is achieving about 17-18 psi. I am wondering if it's normal that boost kind of jumps from 5 to max psi suddenly? There is not much of a middle ground between 5 and 15 psi, for example. It would be difficult to hold 12 psi boost. Driving with 5 psi, a slightly increased push on the gas pedal results in a quick build toward the max boost pressure.

Is this a boost pressure leak? I'm pretty sure I don't have one. The car runs really well. Holds 18 psi vacuum at idle. It's possible my cycle valve has a small leak which I will repair. A/F ratio is pretty normal if not a bit rich (I need to try adjusting the FQS at the DME).

If I left out some important info, please let me know. Any guidance and ideas are appreciated. Thanks.

walfreyydo

A boost leak would show low boost pressure on the gauge. It wouldnt go past a few psi depending on how large the leak is.

Smaller turbos tend to spool faster. I dont have a turbo, but in other cars I had (03 VW GTI 1.8T) the boost came on very quick (it also had a tiny k03 turbo).

Sounds normal to me

bonus12

Thank you for your reply. It's the stock K26/6. I didn't even notice it was happening for a while, but then I realized there is some threshold that is reached that makes the boost increase as described. That's why a boost leak crossed my mind ... as if the leak is overcome, but I was grabbing at straws.

ElRicardo

What you are describing is pretty typical, the turbo on the 944 is pretty much an all or nothing transition to the higher boost levels. One also has to push that gas pedal way in to get that boost to come in as well. So seems pretty typical. Enjoy the whoosh!

bonus12

Never gets old!
Thanks for the reply.