Open Loop Maf Tuning

[Russ K]

Thanks! This config is working, but my commanded AFR is jumping around. When I have the engine off with key on, it says it's commanding 14.00, but I have the Base AFR for PE set to 14.7. Then when I'm driving around it jumps around between 14.2 and 13.8. Could the AE modifiers be messing with my commanded AFR?

That is normal, you need to set the PE enable TPS to 0%.

Russ Kemp

[mtcrusan]

Mitchell, what size pulley are you running now with the kr? The mods you have should support the 3.4

I was running a 3.4" and I jumped to a 3.6" recently.

[00GTP]

I was running a 3.4" and I jumped to a 3.6" recently.

Well, like i said, you should be able to run that 3.4 even on 91 octane. So it's time to tune that kr out but maybe you should start another thread about that.

[mtcrusan]

Well, like i said, you should be able to run that 3.4 even on 91 octane. So it's time to tune that kr out but maybe you should start another thread about that.

I have been fighting with tuning the fueling at part throttle for a while. I have a WB installed permanently (LC-1). I thought I was good in OL, but when I switched back to CL my trims are rich and my WB reads lean. I'm stuck there. Attached are my current scan and tune. TIA!

[Russ K]

If you have no exhaust leaks by the wideband, then your wideband is not reading correctly. Very common on the LC1.

Russ Kemp

[OldskoolGTP]

Thanks! This config is working, but my commanded AFR is jumping around. When I have the engine off with key on, it says it's commanding 14.00, but I have the Base AFR for PE set to 14.7. Then when I'm driving around it jumps around between 14.2 and 13.8. Could the AE modifiers be messing with my commanded AFR?


That is normal, you need to set the PE enable TPS to 0%.

Yeah, I did that already. The commanded AFR starts at 13.8 and goes up to 14.x or it can go down as low as 13.6. Can't I just keep it at 14.7 all the time? I can't get the MAF dialed in at idle speed because of this.

If you have no exhaust leaks by the wideband, then your wideband is not reading correctly. Very common on the LC1.

Well is that a problem that can be corrected? Because I too am using an LC-1 and I don't want to be fighting a losing battle here. I can't get my car to idle below 2000RPM and I've got a good mind to believe it's because my AFR's are way off.

EDIT: I have a new problem. Since I've started tuning I've been unable to get my car to idle below 2000RPM. The only way I can get it to idle normally is if I upload the calibration I used last fall before I started changing things. The only way I can get the car to idle reasonably is to drop the MAF values to the point where my WB constantly reads 21.x. If I crank it up to where it reads between 13-15 my idle is 2000 RPM.

[louvered97gtp]

If you have no exhaust leaks by the wideband, then your wideband is not reading correctly. Very common on the LC1.

Russ Kemp

What is common about the LC1 not reading correctly? Is this usually due to unit failure, or installation error?

[GTPNoga]

Russ,
I used this method to tune my car prior to XP cam install. Worked like a charm. Now that I have an XP cam , will I get the same results?
What are some of the hurdles you encountered when tuning a V6 with a cam?

[usd2sing]

hi Russ.
i've been struggling with lean idle. (15.7-16.5afr)
this morning i used your write up and had it dialed perfectly.
commanded 14.7, netted 14.7 with b1s1 unplugged etc after 3 adjustments.
follow the how-to to the letter, worked awesome (0-1%)
hooked o2 back up, put the system back to normal (tps/ect/pe etc etc) and im right back where i started. (maf showing +9% on average again)
all o2 sensors are brand new, even the wb sensor has less than 1hr on it,
this is my only area of issue, all other areas im catching commanded perfectly.

any suggestions where to look or point me in the right direction would be greatly helpful.
thanks
dan

BTW....your message box is full..LOL

[Russ K]

Sounds like your wideband is inaccurate.

Russ Kemp

[Eddie-98GTP]

Or maybe a vacuum leak.

Remember, you will hit the same MAF frequencies at idle as you do in other parts of the drive (decel for example). This could cause your idle trims to be off while the trims in other parts of the MAF table are dead on.

[usd2sing]

car never left idle areas, parked in the garage for the testing/tweaking.

i'll try it again with my LM1's, when it cools down some, i know thier dead on.
thanks guys.

anybody wanna buy a dynojet with new sensor? LOL

[usd2sing]

good call Russ.
using my other wb's the write up worked flawlessly.
trimmed out to zeros and 1's.
thanks a bunch.

[IndeedSS]

Since Russ mentioned following up the OL WB tuning with the "STFT+LTFT Method", I figured this would be the right thread to ask about this method.

I've tried the STFT+LTFT tuning, using info gathered from different threads on here, but never found the actual setup needed to do this. Things like setting up the PID with the best method for filtering etc. The reason I'm bringing this up, is I tried this and it threw off my already decent LTFT's.

Since I watch my trims all of the time what occured to me when seeing a +3 STFT and a +3 LTFT is that I would now be adjusting by a +6 even though it seems adjusting by the LTFT by 3% or even 1.5% would be a more accurate process that adjusting by 3-6%.

Can anyone help with the steps to doing this correctly and explain the reason why STFT+LTFT is more exacting versus tuning a learned LTFT?

[GeforceXtreme]

Since Russ mentioned following up the OL WB tuning with the "STFT+LTFT Method", I figured this would be the right thread to ask about this method.

I've tried the STFT+LTFT tuning, using info gathered from different threads on here, but never found the actual setup needed to do this. Things like setting up the PID with the best method for filtering etc. The reason I'm bringing this up, is I tried this and it threw off my already decent LTFT's.

Since I watch my trims all of the time what occured to me when seeing a +3 STFT and a +3 LTFT is that I would now be adjusting by a +6 even though it seems adjusting by the LTFT by 3% or even 1.5% would be a more accurate process that adjusting by 3-6%.

Can anyone help with the steps to doing this correctly and explain the reason why STFT+LTFT is more exacting versus tuning a learned LTFT?

I actually tried the STFT+LTFT historgram and when I was applying the information from the scan into my bin file it was throwing off my fuel trims even worse. So I went back to using the wideband to tune the idle/cruise/WOT maf and it seems to get the fuel trims much closer to 0.0 vs using that STFT+LTFT.

I am going to try going back to using the old LTFT vs MAF table that I was doing months ago. i think I was having better luck with that hisgram vs STFT + LTFT for tuning the mafs idle/cruse range.

[Eddie-98GTP]

Use LTFT only, and let the PCM learn the trims for at least 15-20 minutes before applying the changes (a couple key cycles helps as well). Using STFT almost has to throw off your trims once you get close. STFT is an immediate temporary fuel adjustment, whereas LTFT is a learned value over time.

Personally, I let my car learn for at least a day in most cases, but I drive my car 25 miles / 45 minutes each way to work and back home every day so getting enough drive time is never a problem. I also do not (normally) drive JUST to tune the car, I usually tune while I drive. I understand some can not do this, or have a 10 minute ride to work (F you BTW if this is you (J/K)), so this may not be a viable technique in those cases.

[GeforceXtreme]

Use LTFT only, and let the PCM learn the trims for at least 15-20 minutes before applying the changes (a couple key cycles helps as well). Using STFT almost has to throw off your trims once you get close. STFT is an immediate temporary fuel adjustment, whereas LTFT is a learned value over time.

Personally, I let my car learn for at least a day in most cases, but I drive my car 25 miles / 45 minutes each way to work and back home every day so getting enough drive time is never a problem. I also do not (normally) drive JUST to tune the car, I usually tune while I drive. I understand some can not do this, or have a 10 minute ride to work (F you BTW if this is you (J/K)), so this may not be a viable technique in those cases.

Yup you are right. I just sent you a PM as well if you don't mind.

[IndeedSS]

Since the trims were much worse using the STFT+LTFT, I'm using only the LTFT as well. My car takes about a week (300 miles) before the LTFTs settle in. I know they're done learning when I can accurately predict what the LTFT will be when I change throttle position. For my car this is about a week of driving back and forth to work (60 miles each day).

[MMGT1]

Indeed, a NB is VERY ACCURATE at 14.7:1 I think you should try using your NB's in cruise to tune your fuel using the ST/LT method. In a scan, find your switch point from cruise to PE and use the WB to tune your PE. It has worked like a charm for me. If you smooth the transition from cruise to PE manually, which I also recommend, make all adjustments + ones to blend it. When its done, should be a nice steady rising curve, no humps! I have seen tuned MAF's that are like a rocky road and it does not compute. We rise so fast making MAF a steady constant makes the most sense to me, but if the guys want to chime in, the floor is yours!

[IndeedSS]

Indeed, a NB is VERY ACCURATE at 14.7:1 I think you should try using your NB's in cruise to tune your fuel using the ST/LT method. In a scan, find your switch point from cruise to PE and use the WB to tune your PE. It has worked like a charm for me. If you smooth the transition from cruise to PE manually, which I also recommend, make all adjustments + ones to blend it. When its done, should be a nice steady rising curve, no humps! I have seen tuned MAF's that are like a rocky road and it does not compute. We rise so fast making MAF a steady constant makes the most sense to me, but if the guys want to chime in, the floor is yours!

I do use my narrowband for idle and cruise. My MAF curve is very smooth. Numbers aside, the visual curve looks like a stock one. Once my LTFTs settle at 0 you can still see small changes in the STFT. This tells me using them in the tuning formula would throw off my already 0 LTFTs.