I am having an issue with my supercharger tune. The afr is set to around 11.5 at WOT and remain there most of the time. When the temperature goes above 90 degrees outside my afr drifts to 12.2. Is there a table that causes the maf to look at air differently with termperature? If so which table is this?
Also is there something that changes what your PE table is calling when the temperature changes?
does your engine coolant go up? is it your wideband that drifts? or commanded AFR that goes up to 12.2. there are multiple tables in the cl-ol fuel page that modify the PE if not set to 1. but they all seem to increase fuel as temp rises, not other way around.
Last edited by carlrx7; 09-24-2009 at 09:42 AM.
I was starting to think my wideband was playing with my mind. The commanded AFR is 11.3 on the PE table. The reading on my wideband shows it going lean to 12.5. The problem appears to be caused by a dirty/lazy maf, once it got cleaned the AFR returned to normal. I think the temperature going up has nothing to do with it as it was just a coincidence. I tried again the next day when it was cool and the afr was still lean. I did a fuel pressure reading and it held 57-58 PSI all the way to redline so that is what made me conclude it was the MAF getting lazy. At idle the pressure is 60 PSI and once I get into power the pressure drops to the 57-58 range and holds to redline.Originally Posted by carlrx7
I think all SC/Turbo cars should have a wideband installed. The lazy maf thing is not new especially if the crankcase is vented to the air cleaner which is before the MAF eventually it gets oily and dirty. Also if you accidentally over fill your oil like I did the intake track get really oily and the problem last for some time...
I think the other than cleaning all the time I will just compensate via the maf table by adding more fuel as needed.
Last edited by Mickie Poon; 09-25-2009 at 06:18 PM.
OK I am having problems with this again it's not the maf. My AFR drift lean as the outside temperature increase. On a cool day I am at 11.5 across the board at WOT. As soon as the temperature goes above 90 F my AFR drift to 12.2. What is causing this I am assuming my IAT goes up on those hot days. I saw a couple of table the "IVT" table and the Flow vs. IAT has anyone played with these tables?
Any help would be appreciated there must be a table that I could set to prevent my AFR from drifting lean during hot days.
Bump for answers
I take it you did the VE tuning with the bluecat program? Also, the COT multiplier needs to match the PE multipliers highest number, without that when you go into COT or emmissions test, it will override the PE setting.
Edit: I was mistaken tunercat for bluecat...my bad. Also, the ktoonsez program looks pretty good, I will have to try that myself next time.
Last edited by BBA; 02-17-2010 at 07:46 PM.
The COT has been disabled also no tuning was done with the tunercat.
post up ur tune
Bader Norris
MEP Tuned
Telephone: +965-55446651
Email: [email protected]
That never works correctly. Go ahead and set the multiplier to match the PE multiplier.
I thought the 2007 has the virtual VE calculation tune (no VE tables), meaning that if you did not use the program to tune VE, then you are only MAF tuning. After drastic mods such as adding a supercharger, you need to set the tune completely, raping the MAF table is not all that is required for it to run right.
Last edited by BBA; 02-13-2010 at 07:12 PM.
Here is my tune take a look and let me know what you think
Do you have a logged run? I would be willing to bet that, along with changing the COT multiplier to 1.3 to correct for the bug where COT disable does not always work, you are running into greater than 10,600 Hz from the MAF and may be reaching your airflow limit. Might be time to scale IFR to get past fuel limits.
Thanks for your input here is the log of my run unfortunately I could not go more that 6k on this run. The AFR would not drop and it would have on a cold day. At WOT on a cool day it would drop to 11.6 right away however during this day WOT was 12.6. The only way I fixed the problem was scale my maf to get more fuel. Once that was done things were fine again until it got cool out again. Now on WOT my AFR goes to 10.6 or richer.
If COT is the problem why does it only happen on hot days? Also why are you suggesting rescaling my IFR when maf frequencies exceed 10,600? I thought the maf doesn't top out till 12,200 Hz.
Ok, COT only comes on when the PCM thinks the cat temp is elevated. I have no idea when that would be, whether hot or cold weather. Your current COT value is too low to even cool the cats, you need it to match the PE at a minimum or you will get inconsistant runs.
That log file shows nothing wrong, no where AFR would be dropping out under WOT.
Another thing about AFR, if your MAF is raped to counter another problem, it will be inconsistant. I would suggest you set a MAF disabled tune, log for VE error, use the program to generate VE to correct for the error, then load that tune with enabled MAF, then retune MAF.
About the MAF question, your tune had MAF values statis above 10600 Hz, so high RPM WOT may go over that and not get the fuel it needs.
Last edited by BBA; 02-17-2010 at 06:59 PM.
I adjusted my COT to match the highest PE which is 1.35. I will do a VE tune and do as you suggest. What do you think about disabling the master cat test found on the diagnostic section of the program? I have a cat on my car but there was a problem with the 1g program from the factory giving "Cat performance errors" when there is no errors. I believe GM had a service bulletin on that problem. Maybe as you suggest the car thinks the cat is over heating then it goes into protection mode giving me the inconsistent AFR's.
You have a good point about COT it is probably in the hard codes of the ECU. When COT comes into affect nobody really knows but perhaps on the really hot days the algorithm trip the COT more so then when it is cold out.
One other thing, check for cold startup tables that change fueling for a certain time after startup. I did help with a guy saying he would go lean at the track but logging during driving was fine, turned out he was shutting down between runs and not waiting two minutes after start point before going. A simple startup modifier table change cured it, I can't recall which table it was, it's not in my TBSS but was in his (I think Silverado but now I am not so sure).
Reply With Quote