VVT tuning proposed method

[blandmiller]

Alright, I am finally going to pull the trigger on manipulating the VVT tables and verifying the effect on the dyno. After many hours of reading and studying the mechanics of VVT, my method will be:

Change all exhaust cam timing to '0'. Run a dyno pull.
Change all to 14 degrees and repeat pull.
Retard all an additional 5 degrees and repeat pull.

Find the torque crossing point relationship of the three pulls to identify the optimum Rpm to start the VVT. This will just be a starting point because I assume the target Rpm will change with AFR and spark timing.

The next step will be to tune AFR and spark advance for the new cam timing adjustments. I will most likely pull several degrees of timing and work my way into it. I have already reduced the timing in PE when I changed the PE AFR from 11.5 to 12.9 due to KR.

I'm looking for everyone's input as to what I may be neglecting.

[Rhino79]

I am very interested in the VVT timing, I just don't have good access to a dyno. Good luck and keep us posted!

[ScarabEpic22]

So, Ive been thinking about the VVT tables we have access to, and Ive heard that the main table is only good under PE mode. So, what happens if we have PE mode come on early and therefore let the VVT kick in and make more power more often? Probably have to play with the load %age setting so you dont get PE everytime you drive normally, but personally I romp my I6 at least 1x every time I drive it once its warm.

[blandmiller]

I interpret the VVT/PE function just as you describe. There would be no advantage to the VVT becoming active unless you were in PE. I have already adjusted the PE enable Rpm and % load to maximize the effect while not being a serious detriment to mileage. The power is now much more linear.

[ScarabEpic22]

Gotcha, so what did you change in the tables? I dont really have time to play with it now, but hopefully I will in the coming weeks.

[blandmiller]

I haven't had a chance to change the VVT tables, yet. From what I remember, I reduced the PE enable Rpm to 2400 and lowered the enable TPS% (or load %) by ~10%. My logged data appears to indicate that the PE delay time is tied to the TPS (load) values; ie, you have to be above the TPS (load) value for the duration of the delay time before entering PE. The Rpm enable appears to override the timer delay value. I use PE more than I did in the past, but the AFR changes and the increased power balance the fuel I use and my mileage actually went up.