Hello - On the drive home I engaged the turbo, and noticed a low "pop" sound, then the sound of rushing air, and then the engine stumbled. If I keep my foot out of the gas it recovers, and drives very smooth, but if I go much beyond the first few moments after the whine of spool up I get that popping noise and the engine runs rough. I have a boost control valve spliced in and plan on taking it out to see it that is the problem. No smoke, no loss of low end power.

Thank you

Check out all the hoses from the turbo to the throttle. A ed or loose hose will give the air sound and performance problems that you are experiencing. Often they "rot" from oil and will get soft near the turbo and coing back out of the intercooler. Jon

I had similar issue... turned out to be the turbo exhaust w/a crack underneath. But at 209k I expected these things and replace same . I was shock to see the power that I had been missing all of these years. db 89 745 tic

Probably unrelated, but I had a stumble at boost - and the turbo needle would fluctuate at times when I was just cruising. After the tech adjusted the waste gate - turned out to be a bad distributor.

--
'Be blessed in your quest'' 89 764 (110K), '94 940T (180K)