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is my turbo dying?[740-760/1986] posted by Alex Hughes on
Wednesday, 19 August 1998, at 9:20 p.m.
Car starts and idles fine. When accelerating off boost, things seem normal (but slow.) When I just begin to get on boost, the car stutters, does not accelerate, and spews black smoke. BUT if I floor it, boost goes to normal level and NO black smoke. Acceleration is a little slower than normal, but NO black smoke. My gas mileage is down by about 30%. If I keep off boost, everything seems normal. Slight boost=black smoke. Full boost=no black smoke.I can't figure this one out. I've checked and rechecked all the turbo hoses. The turbo shaft does have a little play, about 1/8 inch, and it seems as if this is the same amount since I've had the car, 15 months, 41k miles. Help me solve this. I have also had tons of new engine management related parts. I thought the cat may be plugged but muffler shop said no. Anyone?
Alex Hughes
1986 745T 115k
Alex
Re: is my turbo dying?[740-760/1986] posted by Don Foster on
Thursday, 20 August 1998, at 7:56 a.m.
Alex ---
If you're really achieving the same level of boost pressure as before, then the turbocharger is doing it's job -- compressing the air into the intake system to the same pressure as before. The engine doesn't know or care how the air gets there, or how well the turbo is working -- only that the air is there at the required pressure.
I would follow Nick's suggestion to look elsewhere first (cheaper, too). Black smoke usually indicates too much fuel (relative to the air), whereas blue smoke usually indicates too much oil. Other Bricksters have chased problems like this and found defective FPRs or vacuum lines cracked, plugged, or falling off. Be sure ALL the large hoses (particularly the high pressure hoses) in the induction system are intact, not split.
Even a new AMM, as Bob suggested, is a lot cheaper and quicker to check than the turbo.
On the other hand, it sounds like you REALLY want a new, water-cooled turbo. Now's your chance.............
--Thursday, 20 August 1998, at 9:33 a.m.
Yes, continue to check for other problems...the turbo seems fine if it works at full throttle, full boost.
Look at the bypass valve near the radiator in the turbo line....it loosens and allows boost to bleed off before engine, yet amm keeps fueling as if boosting...results in black smoke.
Why it doesn't do it at full throttle is another story...maybe the leak is small.
Look for pressure leaks in induction system...maybe a hose blew off somewhere.