5.3 first attemp at a tune may need some adult supervision

[Redtruck1]

Okay so search lambda error setup and you will have to log AFR commanded hi res, commanded lambda and log your wideband in lambda. Setup user defined lambda error and the histogram gets copied then paste multiple to the VE table in the idle area. If you command 1.00 (typically 14.68) the histogram will show say 1.02 for example. That's a 2 percent error that gets pasted to the VE table. I run my AFR around 15.2-14.8 in the drivability to run a little cleaner and better mileage. Logging in lambda is an absolute easy way for us begging rs to correct fueling issues.

I don't have the lambda option with my wide band just AFR. Is there another name for VE? I set the AFR at 15.2 and changed the low and high octane timing 6 degrees, got the truck to pass emissions but still have the fuel smell and cant get the actual AFR on the wide band higher than 14.1 school me please.

[Cyrperformance]

What wideband are you using?

[Redtruck1]

PLX gen4 with bosh LSU 4.9

[Cyrperformance]

It should read Lambda, I looked at the sire and it shows, so you will have to program the outputs to read Lambda. Read through the instructions thoroughly, not saying you have not already but you may have missed something. As online searching "Lambda setting in HPTuners for PLX wideband" may have the answer and lastly the dreaded phone call to the manufacture may in deed be the easiest as they should have some knowledge of what is required.

[Redtruck1]

The guide that came with the plx said to divide the AFR by the stoich value to obtain the lambda value.
so if my AFR on the wide band reads 13.6 and my stoich value is 15.226 that makes my lambda .92604755am I reading this right?

[Kevoscamaro]

1/Eq=lambda
1/lambda= Eq
Stoich Afr/command afr = Eq


http://www.hptuners.com/forum/showth...Eq-Ratio-Chart

[Redtruck1]

lets say my lamda is 0.9196 that makes desired EQ 1.0874 how do I convert to change the VE table to change the AFR on the wide band. also to get rid of the rich situation from the cam overlap. I am thinking that I don't understand VE like I should is their a good reed on here for VE operation and function.

[Redtruck1]

Originally Posted by WeathermanShawn at efi live june of 2011


...Basically it mimics what a dyno curve with headers looks like..
+1. In theory, it should precisely mimic the torque curve of the motor.

Not dumb Q's at all, they're very good EFI101 questions! Elaborating on what joecar and WeathermanShawn have said -

VE Table: The VE table is a description (from us humans!) to the PCM of how much airmass the motor should physically 'process' under any given condition; the PCM has no actual way of double-checking that the VE table is right or wrong, the PCM just operates on good faith that the numbers in the table actually match the engine it is commanding when making its fueling decisions - the VE table is our way of telling the PCM how the motor actually breathes.

MAF: the mass airflow sensor is a bit different than the VE table in that it is an actual sensor (not a theroetical model, or description of airflow) - SO, if you can get a calibrated MAF sensor then the PCM will know exactly how much air is being ingested by the intake. The issues with the MAF are (1) they are not super-accurate from the factory, (2) they can only read steady airflow, (3) on Gen-III motors, they are only useful up to 512-g/sec.

CLOSED-LOOP AND FUEL-TRIMS: Because we don't live in a perfect world and sensors have production tolerances, and 'identical' engines from the same assembly line can vary in their VE enough to affect fueling, and engine components wear over time enough to affect fueling, and gasoline is different from pump to pump, and ..... GM added a system of narrow-band oxygen sensors and 'fuel trims' so that the PCM can adapt to real world operating conditions. Simplest words, fuel trims are the PCMs best guess at how far off its fueling calculations are, in percent; in our PCM tuning efforts we desire trims (LTFT) and wideband readings (BENs) to be as close to zero as achievable, usually dialed-in within +- 1%.

Answering your original questions:

IMO you calibrate a MAF as soon as you buy a car; to whatever degree it is inaccurate, it will directly affect the fueling/economy of your vehicle. The Closed-Loop logic should be seeing the inaccuracy of the MAF and adjusting for this, it will show as non-zero fuel trims.

You must update the VE table anytime you physically make an alteration to the engine that changes how it breathes (exhaust, induction, camming, turbo/blower), or how it fuels (injectors, regulator, fuel pump). VE table inaccuracies will also affect fuel trims. And little changes matter, on my own truck a 2% change means the difference between 15+ MPG and 12-MPG.

Your long-tube modding example: usually (!) when adding headers, the motor will breathe a tad less airflow below peak torque, then show a gain 4-5% more airflow at peak torque, and hold those gains to just after peak HP - or so we hope! All of this actual airflow behavior will depend on the specific combination of induction, camming, headers, exhaust, etc but I would not expect the entire VE table to go up 5% because in reality the new headers will not make the motor breathe 5% more airflow 'everywhere', that's just physically not realistic; after fully tuning the vehicle using a wideband you will see the VE table change in those exact cells where the motor actually processes more (or less) airflow. In fact you can read the VE table and see where and how much your 'mods' have helped or hurt the engine, because the cells where VE had to be adjusted are the places where airflow was directly improved or hindered, and to what degree - if you make a 'mod' and
your VE table doesn't change (throttle-body spacers anyone?!) then you did not change the behavior (performance or economy) of the engine at all!

The accepted best practice on how to evaluate and update the VE table is to drive the vehicle logging PCM parameters in combination with feedback from a wideband sensor (which tells you exactly how rich/lean the exhaust really is); one widely accepted method of doing this is published as the EFILive AutoVE Tuning Tutorial; WeathermanShawn and joecar have also recently developed an alternative method they call CALC.VET, it additionally considers LTFTs and this process is receiving many positive reviews and compliling a successful track record.

[Redtruck1]

I added 5% to my VE table. During warm up after the change the AFR runs around 16.7 down to 15.4. Then after the engine gets fully warmed up and in gear the AFR drops down to 13.9 to 12.6 this also happens during coasting in gear. After I get to highway speeds the AFR stays at 14.6 to 14.5. Is it wise to selective select RPM ranges in the VE table and bump them up another % number? Seeking more insight into the VE table.

[Redtruck1]

I seem to have missed a response to the ve question. I believe I am close to getting the tables so they are workable, the fuel smell is gone for the most part and the trucks performance is where I thought it could be. the program didn't respond very well until I adjusted the VE table, so my observation is the bigger the cam the closer you need to look at VE and its supporting files and matching the stall speed.

[Cyrperformance]

Have you calibrated the MAF or are you running SD no MAF? The new version of HP VCM Scanner has the VE error configuration built in and also has the PLX wideband already configured for the scanner. The Tuning School has really good videos on YouTube for the basic functions of the new software.

[Redtruck1]

no calabration of MAF. I thought the MAF was as is you just had to work around it as it was. do you have insight in how to calibrate the MAF sensor?

[5FDP]

Kind of the opposite of tuning the VE, instead of disabling the MAF in the tune you just disable the VE in the tune to run MAF only. Set it to run open loop and disable dynamic airflow. I think stock on most it has it at like 4,000 rpm for when the MAF takes over, just set it to 300 rpm or something like that so it begins using the MAF only.

Then you can create a AFR error for the MAF if you want to use a wideband to tune it.

[Redtruck1]

that is so cool thanks. the truck is in storage but stay tuned for a future post.