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Re: Flaky turbo boost on '89 900 Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Fri, 7 Nov 2003 12:24:31 In Reply to: Flaky turbo boost on '89 900, Jesper, Fri, 7 Nov 2003 12:07:21 Members do not see ads below this line. - Help Keep This Site Online - Signup |
RS makes good points - it could be a sticky APC solenoid, bad connection, etc.
However, the APC could be working exactly right. It cuts back boost if it detects knock. You may very well be on the hairy edge of knock. Knock is influenced by fuel, load, engine speed, timing, engine temperature, spark plug condition, and outside air temp and humidity. Some of those things fluctuate from day to day, and even from minute to minute.
If you're not running premium fuel, try running one step up in octane rating. If the problem goes away, then you know you probably are knocking. Of course, make sure the timing is spot on, that the plugs are gapped properly, in good shape, and the correct heat range for your car. It's possible that your engine is on the verge of knock, and on a warmer day you get knock, and the APC drops you back to base boost; on another day it's a little cooler or a bit more humid, and the intake charge is just cool enough that you don't knock - full boost.
posted by 192.249....
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