Aftermarket Plenum Vs Idle Tuning

[dansedgli]

I was just wondering if you threw a plenum onto a stock XR6T motor would the car idle different to before without a tune?

Which parameters are changed to fix it if it is different?

The reason I ask is that Ive got an AU falcon that Ive recently put a 6 speed, 6boost manifold, gt35r and a nizpro plenum onto and for the life of me I cant get the thing to idle stable when warm.

It seems whatever I change makes little difference and once it warms up the idle jumps up to 1400rpm and stays there.

Ive tried messing around with the ISC, blanking it off adjusting the VE tables, spark tables all to no avail.

I'm running a j3 chip which is pretty much the same as a flash tuner and other than the idle it runs perfect so I'm hesitant to outlay $3k on a full aftermarket computer.

Any thoughts would be good.

Cheers,

Dan

[rob82]

The AU ECU is not the best ECU for tuning boosted applications. Are you still running the std MAP sensor? Are you sure there are no manifold leaks? There is most likely a min TPS for idle value that has been exceeded so it will not be using the idle timing map and the idle control will be in dashpot mode - check that the TPS is good and within range = 0.6V should be ok.

[dansedgli]

Thanks Rob. Ive checked the TPS values and they are fine.

Im using a 2 bar map sensor from an XR6T.

The idle seems to have calmed down now. Im not quite sure why but its fine again after more playing around.

I did some more searching and on the nizpro site found that the plenum should make little difference.

The AU computer and J3 chip is working well. It could use more resolution in the VE table but it does the job. Im running 10psi now and should be able to run 15 before the factory boost cut using the 2 bar sensor.It was at 2psi before.

Based on my old supercharger setup which was making 195rwkw with a flash tune I would say its at 250rwkw now. I need to get some time off to get it on a dyno and confirm.