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just thinking about things... my car is knocking way more now than what it did before the tune.... All we did at the retune was pull back the ignition timing (in effect that should lower the knock substantialy) and leaned the Air Fuel Ratio to 12:1. The tempreture outside when we tuned the car was around 28-30 degrees and now that the air is cooler it becomes more dense... therefore the Air Fuel Ratio would lean out, Correct?

I gather this must be the cause of why my car is knocking so much now.... Does a lean AFR make the car knock??

Yes, lean AFR makes the engine knock. There is less fuel in the combustion chambers hence more heat and knock, put more fuel in which reacts as a coolant and then you have less heat and knock. Hence why factory cars are generally run rich from factory to act as a safety measure.

The old saying is, lean is mean!!! Its great for performance but its living life on the edge. But, 12-1 ratio should be what your aiming for, maybe high 11's if you continue to have troubles.

I had my car tuned at ICE with the PFC...

Just PFC, FMIC, Exhaust on 12psi

It was knocking on the top end of 2nd and 3rd so i took it back.. Nigel told me it was totally safe this time (2nd Tune) but the car still shows the knocking light flashing when in low revs in higher gears...

The light comes on even when i lowered the boost to 9psi which to me says the car is running to lean?

Without a Hand Controller and only Nigel telling me it will be fine, how sensitive is the knock sensor on the PFC?

The dyno really graph really doesnt tell me much whit the ratios at 12-12.5:1 on the first tune by ICE...

Any ideas?

well before the tune my car used show a knock level of 15-25 under hard hard acceleration. Today just hard acceleration it pulled way over 65 knock both times i did it... Not particularly pleased. I know from when I was racing my Formula 3 that not everytime you remap the fuel or ignition mapping that you get a positive result. Theres alot of hard work we had to do to sort many dramas out... We are talking about highly tuned cars here - not V6 ecotec commodore engines so im prepaired to play around and see what we can make of it

  • 1 month later...

By the way, & to answer previous questions.. Yes its standard Injectors, Yes its standard AFM, No there isnt a fuel reg and the reason the car made that power is simply because of the person that tuned it! Ben is fantastic and worth EVERY penny...

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