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Re: Power loss issue/ Check Engine 1990 9k turbo Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Fri, 18 May 2007 05:17:29
In Reply to: Power loss issue/ Check Engine 1990 9k turbo, Newf9000, Thu, 17 May 2007 18:03:39 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Backfires imply to me a leak in the exhaust system, typically around the manifold. That would also explain the O2 sensor fault. The fault is triggered when the O2 sensor doesn't read where the ECU expects it to, or is simply stuck at full rich or lean. If you've got air sneaking in through the exhaust manifold, the O2 sensor will see that oxygen, and determine that the mixture is too lean, and richen up the mixture. When you decelerate, you shut off the input air to the engine, but the fuel is still being pumped in. So the rich mixture in the cylinders gets even richer. Dump it into a hot exhaust manifold with that oxygen from the leak, and you'll get backfires.
So I'd look for leaks in the exhaust system, from the manifold to the turbo.
Your pressure gauge is reading in inches of mercury, not PSI. A perfect vacuum compared to ambient would be about 14.6 PSI (depending on ambient air pressure). -16 In-Hg is about -8 PSI, and about right for idle. But a vacuum leak in the exhaust wouldn't show up on a manifold vacuum gauge.
posted by 192.249....
, Fri, 18 May 2007 05:17:29 <-- Viewing This Message
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