turboracer

I am running the Japanese rs mivec map. I attached an evoscan log from a couple weeks ago. I did richen the fuel slightly since then but the timing is the same.

On my 100 octane tune, I did not lean the afr yet. Adding the timing seemed to bring it back up a bit. I did get a chance to look at another 100 octane tune today. This will give me some direction. My original boost level was 22 psi, I went up to 24-25 psi.

Jason

nj1266

iTrader: (6)

At least on my car this did not happen in testing. Retarding the timing actually made the AFR leaner on my car. I pulled timing 1 degree from 5000+ to cutoff and The area became leaner. In this cases that I highlighted on these charts you can see that it became a lot leaner. But overall the entire 5000+ rpm area is leaner. The AFR in this area was not touched between the runs. The AFR in the 4000-4700 rpm range is richer in the second chart since I added 0.4% fuel.

Chart one. 3 runs. Original AFR




Chart two, 3 runs, timing pulled by 1*, afr became leaner

JohnBradley

iTrader: (30)

Nj1266, interesting. Well this is why Grandma told me never work in absolutes. I have found it to be generally the case, though obviously you have data that supports the opposite conclusion. I will have to experiment with this myself and see what I come up with. One place that I recently saw it was tuning my father's BBC in his Chevelle. Retarding the timing drastically increased the EGT's (retiming the car after a distributor swap) to the point where the rear header tubes were glowing. Though now that I think about it I can see why it would be leaner because any available oxygen would have been consumed by autoignition post exh valve. I definitely will have to research this further now. Thanks for the experiment and results.

John

Pd1

iTrader: (38)

It's common knowledge that advancing ignition timing results in a slightly leaner mixture. NJ's tuning method (using xede, not actual timing adjustments in the ECU) incorporate an additional layer of complexity and may not be the experience of someone testing in a more controlled environment. There are also other variables that would need to be accounted for, but let's just say that one tuner's experience (using questionable tools) doing one test doesn't negate the common knowledge experience of the vast majority.

C6C6CH3vo

iTrader: (9)

Perhaps the timing retard allowed the ecu to run in the high octane map resulting in leaner WB reading.

Or,

Weaker timing gave lower % load where leaner cells are located.

I'm quite a novice on the subject but I agree that retarded timing gives more incomplete and richer burn, right?

nj1266

iTrader: (6)

First, the Xede has nothing to do with it. Retarding timing is the same whether done by the Xede or done by a flash. Why would that make a difference is beyond me.

Second, I did mention that this was MY EXPERIENCE on MY CAR. I did not make a generalization to everyone's car.

Third, did you test the impact of timing retard on AFR on your car? You say it is common knowledge. Do you have any personal experience with this?

Fourth, as I explained the only change that was made in that rpm range was a 1* timing pull. Boost and AFR was left unchanged. I tested a day apart on the same stretch of road @ the same time. That could a variable, so I tested again and got the same lean conditions.

Fifth, What questionable tools? Are you talking about the Xede? When did the Xede become a questionable tool? Are you talking about the Innovate wideband?

Bottom line, if you have done testing and have data on this, then please share it with us. I doubt that you do since you do not even tune your own car.

CRONZ305

iTrader: (1)

the jdm evo 9 mr timing would i see a gain with that with 100 oct?