I'm currently having some fuel tuning issues that have me stumped... any advice would be greatly appreciated.
Right now I have my injector constant set up so my car idles correctly in the 14.8-15.0 range... throttle response is right on. The car will run and drive decent with this setup in open loop. However when I turn the closed loop tables back on the car instantly starts up and idles in the low 10 afr's at the closed loop operating temperature. If I turn closed loop back off it goes back to the proper 14.8-15.0afr.
Any ideas why I would be getting this result? I'm stumped to say the least.
President/Founder - 607 Motorsports
So it does this at full operating temp?
FU Tuning
Yes, when the car is warmed up and should go into closed loop. With closed loop off the car idles pretty perfect at 14.8-15.0. I went out and drove it and it ran decent but then came back and decided to flash the same tune back on the car but with closed loop turned on... when I did the car would barely idle... in the low 10afr's. I flashed the open loop tune back on and bam perfect idle again... I'm lost...
President/Founder - 607 Motorsports
Bad primary 02 sensor?
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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
I hope not... It's a brand new 4-wire heated O2 sensor... I went over the wiring a few times when doing the conversion to make sure it was correct and i'm pretty confident it's right.
President/Founder - 607 Motorsports
Did the problem start about the time you changed the 02 sensor?
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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
I can't tell that because this is an entirely new setup for this season... the 1000cc injectors are new, LS1 TB is new, 4 wire heated 02 is new, fetter tubular turbo mani is new ect... Last season on the only setup I had the car running decently at 25psi for most of the season with 720cc injectors and 28psi on a race gas mix.
President/Founder - 607 Motorsports
adjusting any tables/ values to shoot for stoich while you're in a forced open loop is your problem.
you can't do that. your injector constant is way off.
I understand your reasoning, but its been discussed a million times.. there's other tables that we can't see that effect closed loop fueling. when you disable closed loop you're disabling not only fuel trims, but other multipliers as well that we cannot see or adjust.
logical thought would say "well if I disable trims, and get the constant close to stoich under idle, the trims will be 0 when I turn them back on" and that would be true.. if there wasn't so much more that we couldn't see.
if you want to screw with your idle, leave trims on, adjust your constant, and see if you can get the numbers as close to 0 as possible for IDLE situations. cruise and decel don't count.
even that method is only my best theory.. the more I try to tune with HPT, the more I realize its only good for WOT.. I'm hoping my latest attempt disproves that but so far my success is marginal at best.
I haven't touched my idle VE tables only smoothed them out slightly. The only thing I am adjusting is the constant right now in open loop to get that dead on before I do any modifying to the tables.
President/Founder - 607 Motorsports
if im not mistaken, you calculate the constant and leave it alone then tweak the VE tables to obtain proper fueling. that may be your problem
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
jimmyc99z24 wrote:The only thing I am adjusting is the constant right now in open loop to get that dead on before I do any modifying to the tables.
I'll bold it this time...
you CAN'T do that
which is the reason I said:
myself wrote:adjusting any tables/ values to shoot for stoich while you're in a forced open loop is your problem.
since your constant falls under the "any tables/ values" category, and you adjusted it while in OPEN LOOP, that is your problem.
your AFR is screwed up because you're making changes in one mode (open loop) and you think it'll work with the other (closed loop).
your constant is wrong.
I'll repeat myself:
if you want to adjust your constant and get your idle close to stoich, leave CLOSED LOOP ON. play with the constant until your trims are as low as possible (they'll never be dead-balls accurate).
then, go through the normal VE tuning process.. THIS is the only time you should force open loop (VE tuning)
Edited 1 time(s). Last edited Wednesday, April 29, 2009 9:49 PM
Why is fuel not being pulled in closed loop to achieve stoich? I'd have to agree, triple check the primary O2 sensor. Even if your constant is off a little (or a lot), it should adjust to stoich in closed loop no matter what.
Well after being stumped on this I turned to my good buddy Sweetness for some troubleshooting/advice
We believe the issue is indeed my primary 02 sensor being wired incorrectly so I am going to try hard wiring it in tonight instead of using the rear 02 sensor the way I had it. For some reason it just was not ready correctly in closed loop...
As far as the injector constants I would have to disagree that you cannot tune them in open loop... I have tuned MANY cars over the years and this is always how I tune them. I get the constant as close to stoich as possible in open loop and then turn on closed loop... leaving all the other tables alone the fuel trims should compensate where needed. It has always been my thought that you need to get the constant as close to dead on as possible before allowing the trims to compensate... if you are trying to get a constant in closed loop you're constantly battling with them.
I am pretty sure the issue here is not the tuning method but rather the wiring of the primary 02, thanks to those of you who recommended that and thanks a TON to Sweetness for helping me out yet again
President/Founder - 607 Motorsports
Below is my speculation on what may be going on.
I think that the issue here (at least on the alpha n based VE tables) that the factory GM VE tables are tuned in two parts. The low RPM/TPS VE Cells were tuned while in Closed loop (As PJ says there is other things going on in closed loop we cant see) I have noticed on my car these low RPM/TPS cells get all thrown out of wack when doing PE / VE tuning. So when I do my PE / VE tuning I am only modifying cells above 12 - 15 TPS. I leave everything below that for the most part stock and blend them a little with whats above.
I think that basically certain parts of the VE table are optimized for Closed Loop (because it has been stated Closed Loop still uses these values + modifiers) and the upper parts of the VE tables are meant for strait up PE mode.
This is how GM gets away with only one VE table for both modes because they know on an alpha N / no boost setup the areas in the tables under Closed Loop OR PE mode are going to remain relatively constant in where they are at. This also might explain why GM put the damn PE enable RPM so high because they never really tuned these cars for PE mode from the get go. The whole thing seems half asssed.
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Hahn Stage II - Mitsu TD06-20g |3" Turbo-back Exhaust | 61mm Bored TB |
HP Tuners | Innovate WB02 | Spec Stage 3 | Team Green LSD | TurboTech Upper | Full Addco Sways | Sportlines & Yellows |
jimmyc99z24 wrote:I haven't touched my idle VE tables only smoothed them out slightly. The only thing I am adjusting is the constant right now in open loop to get that dead on before I do any modifying to the tables.
I decided for the hell of it to try this method today.
I have 440cc injectors in my 2004.
None of my VE tables were modified.
I have the car in forced open loop.
I've tried injector constants of .10185, .10194, .10300, .10500.
I noticed two things.
with forced open loop at idle, the ecu commands 14.00 AFR.
second, no matter what happens, my AFR always hovers around 16:1.
there's a fairly large spread in the injector constant and I see little to no difference in idle AFR.
Just how much are you changing the injector constant to achieve stoich at idle?
only after I added 10% more fuel in the idle VE table did my AFR get close to stoich.
I'm currently using an injector constant that does warm starts with no problem (my old constant of .10194 had trouble starting after getting to op temperature).
here is a question i cant seem to figure out... in 2nd gear my afrs under WOT are 11.8-12.0, in 3rd they are 11.3-11.5.... no idea why.. only thing i can think of is the gear ratio but why would that have anything to do with it.. the IAT temps were about the same when i did a 2nd pull and a 3rd pull from 3k in each gear.. or the other thing is my water/meth is lagging in kicking in or something.. dont know.. just wish my afrs would stay pegged at 12.0 all the time under WOT
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
evilmonkitar wrote:here is a question i cant seem to figure out... in 2nd gear my afrs under WOT are 11.8-12.0, in 3rd they are 11.3-11.5.... no idea why.. only thing i can think of is the gear ratio but why would that have anything to do with it..
The load is different, therefore the cell is different. This is where load cell dyno comes into play..
P&P Tuning
420.5whp / 359.8wtq
ImPhat0260/Cavattack2000 wrote:evilmonkitar wrote:here is a question i cant seem to figure out... in 2nd gear my afrs under WOT are 11.8-12.0, in 3rd they are 11.3-11.5.... no idea why.. only thing i can think of is the gear ratio but why would that have anything to do with it..
The load is different, therefore the cell is different. This is where load cell dyno comes into play..
that was my next guess. thanks for the info.
12.33 @ 111.67 mph [Oct 2009]
Dyno'd on 08/02/09 - Mustang Dyno:
327.6 WHP 333.6 WTQ [10.1 AFR]
