Dainslaif

I recently redid my fueling tables which involved recalculating the injector flow rates and multiplier, editing the short pulse width and adders, adjusting when PE kicks in and tuning my MAF table a bit.

The problem I'm seeing is that when I let off the gas to shift / idle to a stop, my car's AFR dips down into the low 11's/high 10's.
http://smg.photobucket.com/albums/v1...ent=Charts.png

The other thing I'm seeing is that during a cold start, the AFR stays around 12 APR for a while, which seems ridiculously low. When I start driving it doesn't improve much until it warms up a bit.

Any suggestions on what to adjust or what to monitor to fix these?

HunterKiller89

iTrader: (1)

these numbers are coming from a wideband, correct?

Dainslaif

Yes. The light blue line in the second set of readings is my wideband. You can see it dip down into the 11/10 range every time I shift.

HunterKiller89

iTrader: (1)

during shifting i believe is normal. It at least does this during my driving.
that pic is way to small btw, im having trouble reading. If this is happening while cruising (out of PE mode) then its completely normal. Shifting will change the RPM, changing fueling requirements, but it wont be instantaneous for the ECU to realize fueling requirements have changed. It will run rich for a second, then that rich exhaust pulse will hit the O2 sensor, and then it will tell the ECM to lean out the amount of fuel to correct. I know since our MAF is a good ways away from our engine, it takes a second for the air velocity by the MAF to actually slow down once the RPMs reduce, so there will also be a delay in MAF readings. Both of these delays are pretty negligible, and should just be blips on a wideband.

If this is however, under WOT/PE, then I'm not sure if its still normal to see that. I guess it depends on if your tune is MAF driven or if its a speed density system, etc. Ask a tuner about that one

Rippin07

It is normal, however, if you like you can tune that big drop out of it, you need to tune your VE. ( the table most people around here think doesnt make a difference.) If you do VE tuning in your part throttle driving area in the lower rpms - from 1500 to 3300 rpm or even as high as 4000 if you really like, the fueling will be alot closer as the VE does all the transition fueling, between shifts and during tip in throttle among other times. For example, when I shift my AFR stays within 1/2 a point under normal driving.

Dainslaif

You should be able to click it and it'll expand to full size HK. The thing is ridiculously wide so I didn't want to post the whole thing on the forum, heh.

It is not during WOT/PE, and you're right, I haven't tuned my VE table yet. (started with MAF since I was testing the new fuel tables and happened to be recording at the time) I'll do some VE tuning tonight and see if it helps. Thanks Rip.

iisbalt

-14 for fuel trim?
Need to get that in line
But other than yet yeah some VE tuning should straighten the afr richness out.

Dainslaif

Yea, I adjusted my fueling tables in an attempt to smooth out the idle and fully retune it, and that made it way more rich. It's a work in progress, but the VE tune should help a lot. ;-)

Dainslaif

So I'm doing the VE tuning, and it doesn't seem to be making much if any of a difference (then again most of them are +/- 4 so that's probably why), but I want to make sure I'm applying the AFR error properly.
I'm calculating AFR error as 100*(wideband-commanded)/commanded so it will return a negative number if it's rich.
Then I take the histo of this number (VE vs. RPM vs. MAP) and multiply it (the AFR error in %) to the VE table (so if the AFR was rich, it decreases the VE number a tad). The only thing the histo filters by is if the box is hit 10 times.

Does that sound right or should the AFR error be positive if it's rich? The way HPT words the VE and MAF tables, it sounds right but I'd just like confirmation since that's the one function I couldn't find on the forums.
Also, it appears to be spiking really far down when it hits the 21 kPa column (full vaccuum), but I also have a histogram recording the pulsewidth. Is that tuneable via the VE table or is this best corrected with pulsewidth adders?

If anyone's interested I can just toss you the tune and my latest data log. Just PM me your email.

Thanks.

Rippin07

When you tune the VE, you need to Disable the MAF and the DFCO, set the MAF error for the first failure to set cel. Also, go into the fuel trims and reset them. Do this when everything is warm and ready to go, then I set my cells to a 5 count ( just to hit them faster and more of them.) ( I will go over it several times.) Then as you stated you multiply the VE by the error % and, if it is - then it will remove fuel in those cells and + will add fuel. I also stay out of boost when tuning VE and only drive up to the 0kpa on the gauge. Also ensure that you are not going into PE mode at all. If your already doing all this then you might just have to keep at it. Mine took about 3 or 4 total hours of tuning time on the road, however I credit alot of this to the 35 mpg I get in the city (cdn gallon).

Dainslaif

Yep, that's what I did to tune the VE. It's looking more like I just didn't set my short pulse adder table correctly. I adjusted that down a lot and it's getting way more drivable. I'm going to try bumping it little by little and get it as slim as possible, then get back to VE and MAF tuning.