NYSS Guy

iTrader: (1)

Guys, I have a 2 bar speed density tune, and I just noticed today that I am running between 11-12:1 afr on decel (car in gear, no throttle). My gas mileage has been bad, so I had a feeling something was going on. I also noticed that I am at 13-14:1 at a cruise on the highway.

Is it okay to run DFCO in a SD tune? And is there something I can do about the cruise afr? I did notice that the DFCO is disabled, but I'm not sure if it needs to be.

Thanks!

Frost

iTrader: (45)

Sounds like it must be open loop at cruise... You can just re-enable closed loop (assuming o2s are still in place) and if you are kinda rich now, it will fix you up (work to maintain 14.6-14.7 avg AFR) and your trims will be nicely negative. Your mileage will pick up a good bit from this. DFCO can be set to work, have a look at the RPMs and MAP at the time you want it coming on, going off and do some fiddling to get it to work right for your setup. This helps mileage too. If you are very rich on decel, it could be VE error or wrong minimum pulse/short pulse adders in the injector tables or a combination of both.

If you are using HPT (or EFIL and someone witht hat is reading) and wanna post the tune and/or log I'm sure that folks would be happy to look and point out anything that they may see.

SSpdDmon

iTrader: (10)

DFCO and SD are unrelated. If you want to turn your DFCO back on, then go for it. Figure out where you have to set the RPM and MAP enablers like Frost said so that it will turn on.

As for having richer cruise AFRs, that needs to be corrected in the VE most likely on a SD tune - unless the commanded AFR is causing it to be rich.

TAQuickness

iTrader: (28)

I run OLSD full time with DFCO enabled. Picked up about 3mpg by enabling DFCO.

NYSS Guy

iTrader: (1)

Awesome guys, thanks for the info!

macca_779

I have DFCO kick in really easily. I have it enable under 55kpa so that its pretty much the throttle that is dictating its actuation which is set at 1%.. I did have it on as low as 10km/h but it was causing the car to buck abit too much when ramping out of DFCO.. I now have it disabled under 50km/h and all is fine. If you increase the DFCO spark ramp in rate say 40%, it will turn it on real quick.

NYSS Guy

iTrader: (1)

Alright guys, bear with me here. I looked at my tune, and I see a couple of places that enable DFCO. First off, and the easiest references ECT's. I put that at a really high number so DFCO wouldn't kick in, as mentioned in the help section of HP Tuners. I am assuming this is because as you are tuning the VE table, you don't want your afr being thrown off by DFCO.

So, if I put that number back to where it was in the stock tune, will that take care of it? I think I have several things that need tweaking. Between some injector tables, the VE needs more tweaking, and this DFCO, and idle tables. I just don't have the time anymore to get this done!

Frost, I am going to try and post my latest scan and tune. I would love some guidance.

NYSS Guy

iTrader: (1)

Okay, tune7a is the scan, and Tune7 is the actual tune file. You might notice in the scan, my wideband starts going a little nuts at the end of the scan. Not really sure what that's about, but I think something is going bad with the wideband.

Also, there is a pretty long highway cruise in there, which might help guiding me with the rich cruise condition. Thanks again guys, I really appreciate all of the help!

Dave

macca_779

If your seeing 11-12:1 AFR on decel DFCO is not your problem. Turn fuel off, goes lean, make sense. Keep DFCO off for VE tuning obviously as it will screw your BEN's. Going rich on decel is probably just asking for more VE tuning. I can't read your log or tune as I use EFI Live. I'm sure help will be on its way soon enough.

NYSS Guy

iTrader: (1)

Yeah, I assumed the DFCO would mess up the scanning when I'm tuning. But now that I'm driving the car every day, I just want to get better gas mileage while I'm not tuning.

Thanks guys for the help!

Frost

iTrader: (45)

That log you have... why not use some of it to correct your VE? Your VE tuning is unfinished. Under your DFCO tab, jack up the numbers for clutch fuel transition so that it doesn't shoot lean on clutch-in and skew your logging.

I took this WOT snippet. Your AFR under boost is about 1.5points off of commanded. Take the loaded VE from the scanner log and paste it over your your original VE using special, multply by % half. I say use the half feature because there is just a little bit of bad data in there. Also, when you are not tuning, why not use short-term fuel trims? until you can get the VE where you want it (and personally I'd use them even when finished).

That's a healthy amount of timing for peak boost too (indicated by values in pic below, the slider is overlayed at peak boost), it's probably fine for a gear or two, but with the cylinder temp rising from pulling through 4 gears, it may prove a tad high. Just something to keep an eye on.

Here is the WOT snippet for those who cannot see the log:

Frost

iTrader: (45)

I just went through your log and made some VE changes based on what I saw there. No exact copy-paste except the copy-paste mult by %-half in the cruise area. do a compare to see how much things were changed. Most came from your logs and the trends in between cells I filled in conservatively by hand.

NYSS Guy

iTrader: (1)

Frost, that is freakin awesome. I know, based on that log, the VE seems off. My concern is, it wasn't before. And the ambient temps were cooler that day then when the car was originally tuned. So, how in the world did it change that much?

I'm concerned that the wideband isn't reading correctly for some reason. I just recently did a open air calibration on it, so maybe now it's reading right, where before it was off??

Anyway, I'll try those changes you made, and see what happens. So, you think I'm getting a little carried away with the timing? It is a 8.5:1 compression built motor. But, I am very open to opinions. I cannot afford to rebuild it now, so if your thinking that's too high...let me know. Thanks again for the help.

Frost

iTrader: (45)

Nevermind, see that you are only running about 7psi. You may even be able to add a lil up top at that level. For some reason, the boost level didn't click as I was copying the log.

I am going to ask again, is there a reason why your STFTs can't be turned back on? (a reason like your o2s are missing/not hooked up...)?

NYSS Guy

iTrader: (1)

Oh, I forgot to answer. I have the front 2 O2's in place. And, no I really don't have a reason for not turning them back on. If I understand what you're saying, turning them back on would help keep the afr in check during normal driving, and my WOT afr should stay as tuned? I just wouldn't want the STFT's on while I am logging/tuning VE, right?

Frost

iTrader: (45)

Just set your STFT enable temp table back to stock. The will bring fueling back to 14.7ish at cruise and bring your fuel mileage back. Leave the LTFTs turned off. They (STFTs) will become inactive if the car is in PE or BE. With all of the IAT/ECT bias issues and trying to get that tuned, STFTs are the way to go to have repeatable AFR from day to day. Best of luck.

edit... oh yeah, leave them off for tuning any areas out of boost (where they disable on their own)

NYSS Guy

iTrader: (1)

Frost, you have been a huge help. Thanks man.