3800 Tuning with ICCU

J.E.T.

TCG Elite Member
Nov 10, 2008
1,319
0
I've been tuning with this ICCU for about a year now. It's the version (1.7D) that will give you random +11 deg timing. But that might not have any correlation to what I'm experiencing.

A/F ratio. I started tuning the car a year ago with a 98% WOT setting. Over this time, I've been gradually adjusting it higher and higher to keep the engine KR free. I started at 98% then 100% - 102% 103% - 104% -106%. It was happy at 106% for a couple of months. But just this week alone, I had to adjust it again. It is now set to 112% to give me my optimal O2 WOT reading which yields 0 KR.

Any logical guesses as to why this is happening?

Car runs great - as long as I keep my WOT O2 level happy.

J.E.T.
 
I

imported_Ron Vogel

Guest
I had a thought about what effect MAF tweaking does last night. This isn't going to solve your problem, but it's food for thought.

The engine during PE mode (WOT) is basing it's descions upon what it sees in the MAP, and MAP values. It determines what the volume going into the motor is to fuel it, and it calculates the fuel and air from that to determine cylinder pressure. Your Spark tables are based off of what cyl pressure is at x amount of revs.

If you skew the MAF values to rich/lean the mix, won't that alter the calculation of the PCM? The skew will cause a false calculation of cyl pressure and thus timing will be affected.

I *think* most of what the mini-afc/ICCU is doing to richen up the mix causes the PCM to determine that cyl pressure is higher than actual. Because of this timing is commanded lower, thus reducing KR.

So acutally richening up the mix with the piggyback device is making it appear that richening up the mix is quenching KR, and reduced timing the byproduct is actually reducing it....

Hmmm, chew on that; time for a WB!
 

CoolGTX

let sleeping dogs lie
Nov 17, 2008
3,241
0
Hotel 4 Dogs
Real Name
J/O
Originally posted by Ron Vogel@Sep 30 2005, 04:07 PM
I had a thought about what effect MAF tweaking does last night. This isn't going to solve your problem, but it's food for thought.

The engine during PE mode (WOT) is basing it's descions upon what it sees in the MAP, and MAP values. It determines what the volume going into the motor is to fuel it, and it calculates the fuel and air from that to determine cylinder pressure. Your Spark tables are based off of what cyl pressure is at x amount of revs.

If you skew the MAF values to rich/lean the mix, won't that alter the calculation of the PCM? The skew will cause a false calculation of cyl pressure and thus timing will be affected.

I *think* most of what the mini-afc/ICCU is doing to richen up the mix causes the PCM to determine that cyl pressure is higher than actual. Because of this timing is commanded lower, thus reducing KR.

So acutally richening up the mix with the piggyback device is making it appear that richening up the mix is quenching KR, and reduced timing the byproduct is actually reducing it....

Hmmm, chew on that; time for a WB!
[snapback]99377[/snapback]​
making me thinks here, Ron.

I cant figure why all of a sudden, I only get 13.5 degrees of timing lately, then when I bump up my timing One notch, I go to 18 degrees of timing(yes you can feel it kick in). I wonder if this started since ive been using the afc/2.0, but in my case, ive got mine leaned out some, ive never had it at 100 yet, its always been set lean;):) I accually ran that 12.51 on 13.5 degrees of timing(woops). Tommorow, I will remove the afc, and see what happens......i'll let you all know results. I even had charles check my pcm for fat fingers last time I was over there, and he said it all looked correct.

J/O
 
I

imported_Ron Vogel

Guest
Well here's the other "scary" thought.

Knock is knock; we don't get 2 or 5 or 7 degrees of knock. We just get knock, the PCM determines KR. If the PCM sees knock, and it calculates we are at x amount of cyl pressure, that it should retard timing by y amount to stop the knock. So what if a skewed cyl pressure calculation causes the PCM to command 2 degrees of KR, when it should be commanding 5 or 7, you'd never even know because we can't see knock on a scanner, we just see KR.

Kind of makes sense why some people can pop a piston with no warning.
 
Old Thread: Hello . There have been no replies in this thread for 90 days.
Content in this thread may no longer be relevant. Consider starting a new thread to get fresh replies.

Thread Info