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Discussion Starter #1
I have an almost stock 89 GT. Within the past 2 weeks I put on a adj fuel pressure regulator, new plugs, cap, rotor, and new plug wires. I have tried my timing from 8 deg to 12 deg. I am still getting detonation at 8 deg when cruising around. Tt only seems to occur at low rpm's(around 2000). I am running 93 octane now and also added some injector cleaner to this tank. Tonight I just removed the air silencer and sprayed cleaner down the throttle body. I also cleaned the maf. The part that has the two little metal things that look like the inside of a light bulb. They looked clean already. Is there anything else I need to clean in the maf? I also had the battery disconnected while doing all this work to reset the computer. What can I do? I am guessing the eec is bumping the timing to high at certain rpm's. Can I adjust the timing and leave the spout out? Will this work? What should I set it at to run without a spout. Thanks!!!

-Tom
 

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For starters, dont ever clean your mass air sensor again. It's not good for it. The wire is very delicate. Anyway, those symptoms dont normally go together. Part throttle and spark knock. You might have carbon in the combustion chamber. Several cans of good injector cleaner sometimes helps, if thats the problem. 12 degrees initial shouldnt cause a problem on 93, so from that point of view im not sure. I'll have to think about that one for a bit.
 

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Discussion Starter #3
Oh yeah, I also set my TPS to .99. It was .74 orig. Would this have any effect on the detonation? I guess not because it was doing it before I adjusted it. Come to think of it, I started noticing it after I replaced the fuel pressure regulator. Maybe this may spark some ideas?

-Tom
 

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double check for vacuum leaks, timing-spun balancer, EGr valve, fuel pressure.
-Mike
 

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Discussion Starter #5
Things I have noticed are that it sounds like one cylinder. I have heard detonation when timing is to high but this sounds like just one marble is in a can slowly rattling around. Would a vacuum leak cause this? would a upper intake gasket leak cause this? I did remove the upper intake to put the fuel regulator on and didn't replace the gasket. Anyone on running without a spout to bypass the timing curve? Thanks!!!

-Tom
 
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