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RPM ERROR + OSCILLATION IDLE

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I'm using hp tuners to tune a manual trans 06 c6 with a novi 2200 supercharger, 408ci ls2, and a cam. When I start the car (not a cold start) the idle stays around 1100rpm and the commanded rpm is 950rpm. It stays like this for around 10s then it idles at 950rpm. After that the idle starts to oscillate where you can see it and as well hear it. It oscillate between 890rpm and 1000rpm. I attached the files. Thank you

Attached Files

Hi Ahmad,

So the issue you're trying to fix is the oscillation?

Things I noticed in your log

MAF sensor oscillation, how big is the cam? I looks like you're still running a MAF sensor which, if close to the throttle will get upset from reversion pulse due to the cam.

02 sensors are doing a lot of work, removing around 15% fuel. Could be caused by the MAF, won't necessarily cause your idle issue but wont help.

Timing, this is usually the biggest factor with stable idle. At idle you're running around 30 degrees timing in your main idle map. Adding to this is your adaptive idle spark control Which I can see your timing is swinging from 20 degrees to 44 degrees. This will cause big changes in engine torque and also move your idle.

As mentioned as well, how big is your cam? A cam with a decent about of overlap will always have an oscillation on idle. However, I think from looking at the log, you should be able to smooth this out a bit more.

Regarding the cam it's not big. I did not finish tuning the STFT and how can I smooth the timing. Is 30 degree in the main idle map is alot?

Thank you

30 is more than needed at idle. I have attached some screen shots of stock ls2 idle settings so you can compare.

Also is the car still running as Maf is? Your maf seems pretty erratic at idle which is why I asked if it was a big cam or not. The erratic readings could be from the engine rpm oscillating or potentially another issue.

I would try reducing idle ignition and also smoothing the idle adaptive spark control and see how that goes first.

Attached Files

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