Need Help with tuning Timing

[RedDjinn]

HI all,
Picking your brains, car is retarting timing. It retarts timing intermitant under load or not, its not teh knock sensor or VVT. Any idea of what could cause this another sensor, loose wire?

[MPS2NV]

actual knock?

[RedDjinn]

actual knock?

Mrt said its all the time any rev even not under load! they feel its a sensor but what sensor other than knock sensor retarts timing?

[TD]

Anymore info? Could be a wide range of things.

Is there a specific amount of timing it is pulling or does it vary? These things pull timing and show part throttle KR whilst the ECU is 'learning' after a new tune is applied and then it goes away after a while. Actual timing being pulled due to proper knocking versus the timing being pulled whilst the car is learning can sometimes be identified by the numbers.

Faulty IAT, ECT and BAT sensors could also cause timing to be pulled, temperature seems to be an input into the timing calcs from what I've seen.

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Also, knock sensors are actually an acoustic (i.e. sound detecting) device. With all your changes and work on your car, something could be loose and rattling around at the exact frequency which is detected by your knock sensor, which then retards your timing.

Are MRT getting this condition only on the dyno and/or road driving? If the dyno only there could be some harmonics from the dyno affecting the knock sensor. Get them to do a data log while driving around the block and see if it happens (i.e. check the logs for timing being pulled and see what other things are happening at the time).

Then there's the usual things to check like tight clamps, clean MAF, spark plugs (gap is correct and they're not cracked) etc.

How tightly is the knock sensor on? Check that too.

And another idea...how old/shitty is your fuel? Could be as simple as that.

Good luck

[MPS2NV]

Maybe this is the edge that TH has over other tuners with their Dyno Cell, it picks up audiable knock rather then trusting the readings that the ecu is showing?

Your knock sensor is doing exactly what it was put there for.

Not in relation to the mps I have heard that in some ls1 engines lifter rattle can be that bad that the knock sensors mounted in the vally retard the timing. (on cars not effected by piston slap...smart arses.)