boost limited..prob with vaccum circuit??


New Member
May 29, 2001
ON my 84 GN (purchased a while ago, just started working on it) I rechecked my vaccum lines and everything was hood up no leaks but some where not in the correct position(not going to the wastegate. THere where other probelms with the car that was causeing problems, ecm going out, burnt injector harness, things of that nature, now its all sorted out i can't get over 8psi. I try adjusting to no avail. It builds boost quickly then slams into a wall, could this be a bad wastegate, or a faulty boost silinoid(spelling, and if thats what its really called) I do have a slight exhust leak but that shouldn't stop the boost like at does (hits a wall). And its not giving any codes


I had the same problem earlier this year and it turned out to be a fuse in the ECM. I don't know that this is your problem but I hope it helps.
Hey, Tx Tech U, Got the same thing happening with my 84 hot air!
Checked all vacum line and replaced all, even ordered new alum. vacum block. Seemed to help, 1 or2 lbs, but still not more than 10psi. May just need to change chip, I'm not sure where to look next.:confused:
well i just got a new chip from conely's, I had the vacume line connect wrong before and it didn't put any vaccum to the wastgate, the boost went really high 22# I connected it corrctly it only went to 9# or so, I thought it was adjustment on the wastegate but it didn't seem to change when i adjusted it. Something made me thing the wastegate is ok but somehting else it stoping the boost. Is that a good way to check if the wastegate is workering or not. Why would it stop at 8# if it was bad??
Here's some links to click on:

GM vacuum hose routing diagram

MY vacuum hose routing diagram

Wastegate troubleshooting flowchart

NOTICE the GM hose diagram shows TWO blocked vacuum lines on the vacuum block! The hotairs *usually* have only ONE blocked line, because our wastegates have TWO vacuum ports. The blocked line on the picture closest to the drivers side goes to that second vacuum port on the wastegate. This is why I also included MY diagram!
(edit some more)--I notice there's THREE blocked lines in the GM pic! Hell, just use the GM for "visual" reference, I guess!

Hope these are of some help!