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Re: Base boost only! Posted by Ari [Email] ![]() ![]() In Reply to: Base boost only!, hmr, Sun, 14 Mar 2004 20:46:11 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Don't assume the APC is broken - There are three general reasons for base boost -
(1) one of the inhibiting systems is active - Cruise control engaged, brake pedal switch on
(2) something wrong in the APC system, and
(3) Engine knock.
Remember - base boost is the engine's reaction to detecting knock. The first thing you should do when you have base boost is to assume the system is doing its job.
If you aren't running premium gas, then get a tankful and see if that helps. Make sure you have fresh spark plugs, properly gapped, of the right type listed in the manual. MAKE SURE THE TIMING IS CORRECT - your '88 has a distributor - make sure it's timed properly.
Look for vacuum leaks - running lean can cause knock. Make sure all hoses are in place. A common one is the fat hose from the intake manifold to the charcoal canister. Since the canister is hidden in the fender, it's easy to miss. Remove the right front turn signal light assembly and peek in. Make sure the hoses are still connected. They tend to oil up, and then boost pressure blows them off.
Check the old spark plugs - do they look a nice light grey, or are they white? That's a sign of lean running. If they're crudded up, with chunks of gunk welded to the electrodes, that's a sign of hot running. If you're running lean, find out why - that could be a vaccum leak, a bad fuel pressure regulator, or even just a crudded up fuel filter.
Yes, a bad O2 sensor can cause lean running, but check the easy stuff first before you start replacing parts.
Once you've ruled out actual engine knock as the reason for base, boost, then you can poke around some more.
posted by 192.249....
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