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Hi! I have a few questions. 1-Changes in ignition time, can affect my AFR numbers? I have a Evo 9 with Aem v2 ems ,around 630whp, I have a ross piston compression 8:8:1 fuel is Q16 my question in a high load 35psi i have linear 16.o of ignition timing i can put more,for example 8,000 rpm 17 degrees and 8,500 to 9,000 rpm 18 degrees? exist any formula to decrease ignition by boost? the aem read oem knock sensor voltage,As I know what the correct voltage is without knocking?

I have taken the courses of

EFI Tuning Fundamentals,

Boost Control and

Understanding AFR, but I still have doubts since English is not my main language if you can help me thank you.

I am still a noob tuner but as the webinars have showed the afr isn't affected by the ignition timing . This is something that you can see for your self if you plug a wideband gauge and do some adjustments . (Of course you need to calibrate your wideband , set the right input to your ecu , etc. ) .

I do not understand what you mean although where you state it goes linear at 16.0 of timing . I assume that you are going lean in mixture but that again will be set up through your fuel table .

To detect knock you will be better of buying an external kit such as the Link G4+ KnockBlock or the Haltech kit or other kits on the market depending on budget . And for boost by gear you might be better of buying the course for boost control to get also some worked examples and more theory around it .

Hopefully someone else with more knowledge can tell you a little bit more .

NO!...ignition timing does not change AFR.

NO!...ignition timing does not change AFR.

NO!...ignition timing does not change AFR.

Triple reply was unintended. Internet flaw.

dynodom and kanjo thanks for response ,see the attach my ignition timing map from my old tuner. thanks for your help.

Attached Files

I still do not understand your issue . Are you just wondering what will happen if you adjust that area ?

Have you got a run file with data log , that might help seeing what exactly is happening .

As others have stated, you won't typically see the AFR change as you adjust ignition timing. The AFR is set at the point the intake valves close so the ignition timing really can't impact it.

The normal trend with regard to engine rpm is that the ignition timing will need to advance as the rpm increases in order to achieve MBT timing. This is because at high rpm there is less time available for the combustion event to take place so we need to start it earlier.This still needs to be confirmed on a dyno though.

From my own experience on the 4G63 with Q16, 16 deg is quite conservative for 35 psi. I'd be surprised if the engine wouldn't want some more timing but of course please confirm with knock detection equipment on a dyno to be certain of what your particular engine wants.

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