stock 05 5.3 - why is commanded/delivered fuel so far off? AutoVE

Working with a stock 5.3 in an 05 Silverado with K&N and magnaflow muffler, otherwise bone stock. 87 octane in PA. Drove with Zeitronix wideband via serial and saw 10.5 afr delivered while trying to do a burnout (dead-stop, 100Kpa). Truck was obviously gutless and didn't execute. Wasn't entirely sure why this much fuel was delivered, so I decided to isolate maf from ve and run an AutoVE per PDF to try and figure out if the issue was maf, ve, or hard-part related. It didn't make a whole lot of sense that it was a problem with the VE table, seeing as it's a totally stock truck, but in speed density, it was definitely commanding way too much fuel. After 11 different logs/adjustments, I pretty much raped 95 & 100 KPA of the B0101 to get the mixture where it belonged. The VE table didn't look good at all, but was delivering what was commanded and actually ran better despite the crappy approach. Didn't feel great about this, but returned to maf operation afterwards anyways to see if it was good, but it couldn't have been more off. Wondering if there is something huge that i'm missing or if i'm fighting myself. I've had success with tuning my 00 2500 6.0 and cammed 00 camaro but am really pulling my hair out over this one and am fearing it' something stupid that i've overlooked. Attatched a file. Attachment 16311

I can't see your tune from my phone, but did you account for PE mode? 10.5:1 (or approx .74 lambda depending on fuel) isn't that far off from the factory commanded fueling in PE mode

PE mode was set to "1" for entire range, and the richest it's commanded in open loop is .95 from 140*f and warmer. Truck was warmed up.

Post tune file.

Both VE and MAF may be incorrect (is MAF collecting oil from K&N...?)... did you inspect the PE table to see what it was commanding...?

Don't set PE to 1 (regardless of what pdf says).

What do you set PE to Joe? I've never had a problem setting PE to 1, I just make sure I command the correct AFR I want. I've done it with PE set to whatever I'm desiring and I haven't noticed any problems with that either :shrug:

I always thought setting your commanded was a better more accurate way to adjust your VE/MAF than using PE.

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Originally Posted by gm22j

Working with a stock 5.3 in an 05 Silverado with K&N and magnaflow muffler, otherwise bone stock. 87 octane in PA. Drove with Zeitronix wideband via serial and saw 10.5 afr delivered while trying to do a burnout (dead-stop, 100Kpa). Truck was obviously gutless and didn't execute. Wasn't entirely sure why this much fuel was delivered, so I decided to isolate maf from ve and run an AutoVE per PDF to try and figure out if the issue was maf, ve, or hard-part related. It didn't make a whole lot of sense that it was a problem with the VE table, seeing as it's a totally stock truck, but in speed density, it was definitely commanding way too much fuel. After 11 different logs/adjustments, I pretty much raped 95 & 100 KPA of the B0101 to get the mixture where it belonged. The VE table didn't look good at all, but was delivering what was commanded and actually ran better despite the crappy approach. Didn't feel great about this, but returned to maf operation afterwards anyways to see if it was good, but it couldn't have been more off. Wondering if there is something huge that i'm missing or if i'm fighting myself. I've had success with tuning my 00 2500 6.0 and cammed 00 camaro but am really pulling my hair out over this one and am fearing it' something stupid that i've overlooked. Attatched a file. Attachment 16311

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So what is the problem? 10.5 afr when standing on the brakes and holding the throttle to the floor at a dead stop? Post the tune .Why are you running open loop??? Why mess with the ve table and maf table?? The truck was gutless because, thank god GM saved the truck from a guy like you. If they did not have failsafe modes for fools they would go bankrupt.

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Originally Posted by picnic_george

what do you set pe to joe? I've never had a problem setting pe to 1, i just make sure i command the correct afr i want. I've done it with pe set to whatever i'm desiring and i haven't noticed any problems with that either :shrug:

I always thought setting your commanded was a better more accurate way to adjust your ve/maf than using pe.

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huh ???

I must have misread something and worked myself in a circle somewhere. I started over from scratch and left pe table alone. Did end up finding a problem with MAF. Replaced maf, did a recal, and fueling was good again.

slows10 - Are you referring to my comment about commanded fuel in open loop? I was following the AutoVE tutorial which said, "7. If your tune contains {B3605}, open calibration {B3605} “Commanded Fuel When in Open Loop”.

The reason I thought 10.5 was a problem, is that 12.2 was being commanded at the given time.

joecar - Is there an updated guide i should be using? Should all fueling commanded be around .85 during AutoVE?

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Originally Posted by picnic_george

What do you set PE to Joe? I've never had a problem setting PE to 1, I just make sure I command the correct AFR I want. I've done it with PE set to whatever I'm desiring and I haven't noticed any problems with that either :shrug:

I always thought setting your commanded was a better more accurate way to adjust your VE/MAF than using PE.

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I agree with you (can set PE to any value, including 1)...

the problem I see very often is that B3605 gets set to say 1.16 lambda (rather than EQR)(due to software installation defaulting to lambda)... if PE was left as stock then it offers protection from this inadvertent mistake.


( some people did not realize software defaults to lambda... not everyone pays attention to units displayed on upper right of table displays )

Not everyone does what you said (about making sure).

gm22j,

some questions:
- do you intend to run with MAF...?
- do you intend to run with NB02...?
- do you have FlashScan V2 or V1...?
- which wideband do you have...?


If you do AutoVE, and you have a wideband that supports serial comms, and you have FSV2, then the Calc.VET thread has a better correction pid (WO2BEN) that can be used with AutoVE.

If you want a quick method of correcting the MAF and getting the VE close, then Calc.VET can be used (and tailored to use either LTFT and wideband, or wideband only)...

but whichever method you use, you must pay attention to whether the MAF is disabled or not (is a MAF DTC present...?), and whether trims are disabled or not (CL/LTFT/STFT/SOL), and what is appropriate to the method...

e.g. if you're doing wideband correction, you don't want trims correcting ahead of the wideband.