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#1554 - 10/31/01 04:22 PM WOT Timing  
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Several things can cause lower WOT timing.

1. G.M to reduce knock issues and to quit needing pre-cats, went with smaller injectors ( to assure hving clean emissions) and less timing.

2. A4 auto trannie, due to factors such as torque management and TCC, tend to kick in/out lock/unlock and thus may have less WOT timing then MN6 6-speed.

3. For CAFE, G.M tends to calibrate more on the lean side to meet MPG requirments.

4. Adding mods without tuning AFR to calibrate fuel trims, increases lean condition too far inducing knock, which reduces timing, which reduces torque.

I have analyzed over 500 PCM traces from over 100 C5 Corvettes and find loss of WOT timing a AFR issue. A MAFT would allow you to correct the problems (unless it is a A4 driven problem)

I find the '01 and'02 C5s tend to have a few degrees less WOT timing then per '01s.

Important functions that should be monitored such as MAF, and injector pulse width.
MAF is reported in lbs/minute, do the math to make it lbs/hour and match that to your injectors which are rated in lbs/hr and then look at injector pulse width to see what the duty cycle looks like.

WOT timing average should be only be calculated when in cell 22 ( or whatever your WOT cell is ) and when TPS is greater then 99.5% open.

My '99 LS1 372 stroker has 11.3:1 engine compression and could not handle as high WOT timing as stock but I still was able to tune to achieve close to 30 degrees in pure WOT condition with zero knock during WOT and only slight knock in non WOT as can be seen below :

http://teamzr1.com/29dwot.html

In all cases of helping others with lower WOT timing, via using a MAF translator, timing was increased, knock reduced, and torque increased.

Running lean, means less load on engine, thus more timing, going too lean induces knock which retards timing.
Going richer means more load, hence less timing.
At the time of WOT, before LTT is frozen, PCM will snapshot and attempt to cure the reading to get LTFT closer to zero, thus a lean LTFT will cause a rich WOT.


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#1555 - 06/17/03 12:01 PM Re: WOT Timing  

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I have an LS1/auto, and I run 32deg of timing at WOT, just before I shift.
I've heard some ppl say this is too high and other's say this is just fine as long as my a/f ratio is ok and KR is 0. Both are ok, is there any benefit in dropping the wot timing and running leaner or richer?

thanks again,

allen

#1556 - 06/18/03 09:45 AM Re: WOT Timing  
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You cannot treat all tunes the same, each car/truck has dfferent mods, weather, type of gas, where from sealevel, how owner drives, etc.

I stay around 28 degrees at true WOT and tune what is needed to assure there is no knock to yank the timing out. I see no gains in going above 28.


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