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Hey guys. Building a tune and im having an issue with my long term fuel trims. Running on Speed density and Cat protection is disabled. Vehicle is a 2008 GMC Envoy denali with a 5.3L. Only thing done to engine is a cam swap (summit racing 8701R1). Injectors are stock and vehicle has factory cats with a aftermarket exhaust. No matter how low i set my VE map, the fuel trims are sticking at -18.7. For the life of me, I cannot get them figured out. Anybody have any ideas? Thanks ahead of time!!
Do you have a wbo2 logging? If so have you tried to disable the O2's and see what the wbo2 is seeing? Could be an actual mechanical issue and not the tune.
Wide band is installed post cat on bank2. Not really sure if thats going to be effective. Was told that after a few good pulls, the excess oxygen will burn off and give you a accurate O2 reading. Not sure if thats true. But with that being said, I appear to be around 14.6 on WB. sometimes the fue trims go to -1 or -2 for a brief moment (no log). Then they go right back to -18 to -30 on long terms
Are you sure its in SD? There is a MAF status pid you can log.. or at least make sure 101, 102, 103 codes are active.
Followed Bentune on ticktock and goat rope garage. Im pretty sure its in SD. I will check that Pid and add it.
double checked all my maf settings. high rpm disable @ 8,000. Low is @ 7,950 MAF frequency fail high @ 0hz fail low is @ 15,000hz Test RPM min @ 1 High count thresh @ 1
Post the file and we can check it for you.Quote:
Originally Posted by PositivePower
This isn't how I do it.. It looks like how you did should work. For sure 1's in all the MAF diag boxes work.
Are you sure your not modifying the wrong VVE table? It should be the "manifold switch OPEN" table
going to "edit" in the vcm editor and selecting the "virtual volumetric efficiency" Thats the map i have been using. Just saw the little pull down tab to change tables.. WAS tuning manifold closed!!!
thats the problem.Quote:
Originally Posted by PositivePower
Thanks for your help!
Definingly start on a fresh table. I looked at your closed numbers and they are way too low. Open/closed is if the manifold has an internal valve I believe. If no valve it runs off the open table. I usually just copy paste the same table in both or even all 4 tables.Quote:
Originally Posted by PositivePower