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Old 12-26-2011, 11:45 PM   #228 (permalink)
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From my experience, if your vehicle came with factory EFI, it's pretty hard to make many improvements on it, especially at full throttle when most are in open loop. I don't know what changes you've made to your engine but if you have raised the compression and still have a functioning knock sensor with the stock ECU, it may be pulling back the timing before you can hear it, even though you are running premium.

I'd suggest doing a bit of experimenting. If you can disconnect the knock sensor without setting any codes, try that and see if you can hear any pinging. Try it with regular grade gas and see if you can hear anything. If you still don't get any, try advancing your base timing by a couple of degrees. This will offset your advance over the whole range. Does this result in any pinging? Does it result in any gain or loss in power? On some engines, you can advance to the point where it will start to lose power before it will start to ping.

It gets a bit complicated.
'95 Ford E150 4.9L I6 Megasquirt MS1 Custom MSnS Extra
'92 Winnebago Elante 33 RQ Ford 7.5L V8 Megasquirt MS1 Custom MSnS Extra
'93 Bayliner 3288 Twin Ford 5.8L V8s (351 Windsors) converted to tuned port EFI. Megasquirt MS1 Custom MSnS Extra
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