Jay Johnson

iTrader: (16)

I'm working on an issue that I'm having with holding idle rpm. I've made some
progress on this issue but I wanted to lay that out and request any thoughts
on the issue.

I have the idle target set to 1000rpm in the Gen7 calibration.

After I start the car it will idle a few seconds near 1000rpm, but then it will
rev up by itself up to 3300rpm, and will not come down

I've adjusted the throttle blade down to fully closed, checked for air leaks,
replaced the IAC, and have even unplugged it and blocked the IAC air
channel, but the same high idle rev occurs.

I don't have even minimal level support for the Gen7(after many unanswered
email questions and phone calls) ,
So, I proceeded to tune with what I've got
The Engine would hold a 3300rpm idle, so I began to adjust the VE cells in
that area(MAP Kpa x RPM) from very rich(per UEGO wideband) to around 14:1.
That backed down the idle rev's from 3300rpm to 2000rpm. I was pleased
I'm making some progress.

That's where I am at the moment. To get the idle rpm down even more, I will
reduce the timing. ecause onthe ramp up to 200rpm I can see that the base
timing values in the ramp up are in the following range:

Timing:rpm:MAPKpa:VE
16.25 : 0800 : 95 : .475
20.75 : 1000 : 90 : .451
22.50 : 1200 : 75 : .426
25.25 : 1500 : 66 : .402
26.00 : 2000 : 54 : .328
25.50 : 2500 : 48 : .328

So there's a little dip in the timing flux that looks like it's capping the idle from
running up to 2500rpm. Also the .328 VE values are close to 0 AFR correction.
Those are 2 of the few cells that I was able to dial in close(so far).

I think that the rich VE's and a high timing value basically rev's the motor up
by itself with more force than the idle rpm setting will hold.
I can see the motor bouncing in the VE cells during idling and once it catches
a certain cell it takes off and rev's up to 2000rpm.

** Would anyone like to share the timing values they are using with any EFI
tuning product?

** Would anyone like to share their VE tables, preferably 402-408ci race
headed motor?
(The Gen7 estimator has the VE table much too rich per the setup I entered).

I can share my tables, but since I haven't been able to control my rpm, so far
I only have a few cells populated with half-decent VE's.

The engine setup is a low compression LS2 402ci with ARF225 70cc heads,
hydraulic 240'ish cam .600 lift.

If I can get the motor tuned decently, then I'll strap on the single turbo kit,
and retune from there.

Is there anyone out there running a Gen7 and LSx?
Where can I get a decent sample calibration file, because the Gen7 is making
some assumptions and populating many things with bad values and that is
making my tuning process very difficult


Jay Johnson