PE tuning..lean on the bottom..

[Redline Motorsports]

Tuning a 01' ZO6 with a head/cam setup. As soon as I nail the motor at 2000 and load it on the dyno, the A/F goes lean to 15-16:1 and as soon as the motor hits 3000 the A/F returns to a reasonable 12.6-13.0. No matter how much I lower the values in the 2000-3500 range of the PE Modifier by RPM table it does really make the change. This lean mixture is leaving a hole in throttle response. The dyno graph shows flat power power until the 3K hits and it picks right up.

As a further note; the way we pull the motors is we hold the motor at 2K at WOT for 3 seconds and then release the load to start the pull. This may be a clue as to where the PCM is at that condition.....

Where else should I be looking?

Thanks

Howard

[johnv]

Std injectors ?
Still runing a MAF ?
What are the feul trims doing before you go WOT.

[caver]

I assume the ve table is spot on at that point?
If using a maf have you also dialled it in?

If everything is right commanded afr and actual afr should be almost identical

[SSpdDmon]

Double check your PE enablers to make sure the values haven't been accidentally changed (B3608 thru B3613) as well as your log to make sure the PCM is reading 100% from the TPS. Assuming that's ok, I'd try disabling the MAF (C2901 thru C2904) and seeing if the problem persists. If it does, up the VE table in the area that you're logging the lean AFR based off of a % error (logged divided by commanded AFR). That should do it. When the MAF is re-enabled, you can do the same % error method for each MAF frequency (3000, 3125, 3250, etc.).

[johnsZ06]

I asked the same question in an earlier thread but go no response.

I also notice the same thing but have no clue yet how to tune it out. Sometimes there is a considerable delay as the engine builds RPM before the AFR goes rich.

I will be keeping an eye on this thread.

[Redline Motorsports]

The car was tuned by another shop so I must admit I am working backwards....It has 30# injectors, MAF is still active, O2's are off (open loop tuned) so no trims.

This tune process started because of the add on of a 90mm intake and TB. Do you guys think is it possible that the 90/90 setup has increased air flow so much to cause this to go lean like this? The customer put the intake on himself and stated that the car had a real lazy spot down low. It was quite obvious on the dyno what he was feeling..

[johnsZ06]

I was looking at the PE parameters. I think adjustement of B3616 and/or B3613 would do the trick.

[caver]

The only way is start at the beginning again who knows what has been to that calibration.

[SSpdDmon]

The only way is start at the beginning again who knows what has been to that calibration.

He can see what's been done by using the compare feature and a stock Z06 tune with the same OS.

[caver]

He can see what's been done by using the compare feature and a stock Z06 tune with the same OS.

I understand that but its quicker to start from scratch than change the gazzilion things they have fiddled with.
Everybody has their own way of doing things and doing it your way from the start is most times quicker than fiddling with someone esle's work.