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Re: turbo clatter Posted by Ari [Email] ![]() ![]() In Reply to: turbo clatter, gremlinsinmysaab, Sun, 24 Feb 2002 20:50:53 Members do not see ads below this line. - Help Keep This Site Online - Signup |
A lot depends on what the clatter sounds like. I assume you don't really know it's coming from the turbo - just that there is a clatter in the engine compartment when the turbo is at full boost.
Seeing as the turbo is spinning up around 80K RPM at full bore, I can't imagine that you're actually hearing the impeller hitting the case. I suspect you're hearing some other sound from the engine that is coinciding with high boost.
The first thing that comes to mind is detonation. Detonation, ping, knock, whatever you call it, it's much more likely at higher boost. Now, there is a knock sensor that will reduce boost when it detects knock. But if there's a problem with your knock sensor or APC system, and you aren't dropping boost under knock, you'll hear a clatter from knock. The real bad news is that knock in a turbo engine will start chewing out chunks from your pistons - very bad news.
Try an experiment - under full boost, just touch the brake pedal - just enough to get the brake lights on, not to stop the car. When you actuate the brake light switch, the boost should drop from full to about half-yellow. If it doesn't, then your APC system isn't working properly.
The other possibility is the knock sensor isn't sending a signal - there are test for the knock sensor, I just don't have them handy right now. But do the easy one with the brake, first.
Ari
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