legacycentral bbs

I'm stumped, so I'll ask you guys, the experts.
Sometimes when I'm starting from a stop. I'll roll on throttle and i'll only get up to 5 pounds of boost (>3,000 rpm). It doensn't pull very hard--Same thing when I'm rolling along, I'll dip into the throtle and only get that 5 pounds of boost and it will pull some what but it will surge some, kinda like it's bogging, then it will pull harder.
Everyonce in a while, I'll get full boost. Like when I romp on it at from a stop light, but not always.
WTF???
Any ideas?
Bad wastegate? Fuel issues? Turbo issues?

thats a good question. my car does this also once in a blue moon. what kind of fuel are you useing and spark plugs?

but sure that you dont have them gapped out too far because boost can blow out the spark and make it mis fire. i gap them around .07 or so.

it also sounds like you maybe are having boost leak. how is your idle? i would also check your pcv hoses to make sure that there not broken or cracked. my car was running like shit because the pcv hose from the crank shaft was basically gone.

are you getting any CEL's?

+1 on a possible boost leak.

It kinda sounds like a bad knock sensor is pulling timing & keeping the car on wastegate boost.

Any CEL's?

Is the OEM boost solenoid connected?

If it is & is working boost should be 8.7 .

i just experienced this same problem with my 91 ss. it just started geting cold up here in the north and it was around 40-50 out tonight. and out of no where as i was cruising around with some friends, it would go over 5 ish psi sometimes not over 7 psi. then out of no where bam 9 psi.

i was thinking the same ... WTF???

then i got on it in first and it boosted 9 again then 2nd just fell on it's face, 5 psi.

my car is bone stock with nothing done to it at all.

i have heard knock sensor, boost solenoid, boost leak, cracked lines for the wastegate/ solenoid.

how do i know if i have a bad knock sensor?

how do i check my pressure sensor?

sorry for the hyjacking of the tread but i would like to know why this just randomly happens

matt

Well if you have a CEL check for a knock sensor code.

If not you may want to check for cracks on the k-sensor, & make sure the connections are OK.

My SS was boosting just 5psi when I got it, & when pulling the codes (5 codes) I noticed the k-sensor was one of them.

I changed the k-sensor with one from a '99 Impreza motor I had (just reuse/repin plug off old k-sensor) reset the ECU & to my amazement CEL disappeared + the car was boosting 8.7psi...

When changing the k-sensor I broke a nipple off of the coolant tank so be careful.

The old k-sensor was cracked.

I've not been getting any CEL...
I'm starting to ask many of the same questions thath mgroshong threw out.
I'll have to look at a Clymers book about some of questions.
Thanks for the help.I'll keep looking. Any other ideas??