VE Tables Unresponsive

**sporkit** · 07-21-2020

Hi,

I have installed a new throttle body and intake on my 6.0 LQ4 engine. I went and re-tuned the MAF as well as the IAC controls and was quite happy with the results. Now I am attempting to tune the VE tables, but can't get the AFR to budge despite some of the aggressive changes I have made. I am always running rich. I have tried just about all I can think of. If feels like something may be overriding my efforts. Posting scan and tune here. Appreciate any feedback.

Engine: 6.0 liter LQ4 out of a 2000 Silverado
Transmission: 4L80e
Converter: 2800-3200 Stall 10" lock up
Heads: Factory 706 casting from a 5.3L engine (resulting in approx 11:1 compression on my 6.0L)
Intake: Ebay Fabricated intake with 102MM throttle body
Cam: 1997-2004 GM LS Series (Gen III)
Lift: 0.585"/0.585"
Duration @ 0.050": 228?/230?
Advertised Duration: 283?/286?
Lobe Separation: 112?
RPM Range: 2,500-6,500 RPM

**ChopperDoc** · 07-21-2020

I’m not on my laptop right now, but venturing to guess.... do you have the MAF disabled? Changing the VE won’t do a ton when using the blended model (aka both airmass models, MAF and VE). I’ll bet if you disable the MAF you’ll see changes when changing VE...

OR

Injector PW is too long in the idle areas? The min pulse width may be too high for your idle, where I’m assuming you are having the problems. Lower the min pulse a few percent at a time (in the idle regions) if this is the case. I’ve had similar issues with large injectors, had the VE down to like 10, still rich lol. Lowered the Min PW data in the lower RPM areas, solves it pretty quick.

Don’t mess with the injectors if your MAF if on. It has to be disabled (failed in the tune) in order to tune VE. I was just giving you a second option by mentioning Min PW if your MAF is already failed and you are in SD.

**5FDP** · 07-21-2020

Clear the fuel trims and the fuel trim learn in the scanner before data logging, you have the LTFT still populated with a value that is skewing the readings slightly.

Are you making changes to the secondary VE table because that is what this vehicle uses in speed density. Then it uses the primary and MAF when blended, so make changes to both primary and secondary so they match.

Make sure you aren't running too much fuel pressure too, needs to be 58psi.

**sporkit** · 07-21-2020

Hi ChopperDoc!

I just watched your video on tuning the IAC. It helped me stop my 102mm TB from screeching at part throttle. Although I have wondered if messing with this is causing me grief at the moment.

Yes maf is disabled. I see the DCT code in the scanner verifying this.

I will check on the Inj PW. Although I still am using the stock 24lb injectors. What are reasonable numbers here?

My last thought is this may be the rich after reflash issue. Is this an issue with gen3 or only gen 4? I have not actually taken the car for a drive yet, it was reading so rich I figured I should get the idle under control first. I will likely give it a start tomorrow morning and wait the 15 mins to see if the issue clears up.

**sporkit** · 07-21-2020

Thanks 5FDP, I will give these suggestions a try as well.

I am only making changes to the primary VE table. Every resource I have seen so far shows editors making changes to the primary only. I will create a new graph for the secondary and modify there as well.

I just installed an eBay Corvette pressure regulator. Will need to buy an adapter to test this out, but it sounds like money well spent.

**5FDP** · 07-21-2020

Computers that have both primary and secondary are different than computer with just a primary. You can upgrade your operating system to a speed density enhanced OS to remove the secondary table or keep it as is.

Calibrations after 2001 got rid of the secondary table altogether.

You can either create a new table that follows the secondary VE or keep the primary table you have and just copy over the matching rows in the secondary table. Make sure you smooth the table after each so that they aren't bumpy or jagged jumps between cells.

**blindsquirrel** · 07-22-2020

Where are you seeing the MAF codes set? Because there's none in the logs you posted.

Basic PIDs: 22
Trouble Codes:
P0122 - Throttle/Pedal Position Sensor A Circuit Low (Current)
P0405 - Exhaust Gas Recirculation Sensor A Circuit Low (Current)
Controller Type ID By VIN: 0
Controller Type ID By OS: 0
Diagnostic Requirements: None

**ChopperDoc** · 07-22-2020

Don’t mess with the injectors if they are stock and on stock data. Knowing now that you have the dual VE tables of the early computers (non 0411) then 5FDP is absolutely right. In SD the computer reverts to the secondary VE table. Also, as he said, clear the trims in the scanner too. This is a standard practice.

To update the secondary VE, just tune the primary, and copy the rows each time. That’s how I did I on my camaro before upgrading to the 0411.

Another way to ensure your MAF is failing is unplug it, provided you have a separate IAT sensor somewhere else, which should be the case with a stock car of this year. If you have the 5 wire integrated type, then do not unplug it. Make sure the MAF fail freq is zeroed out and the DTC’s are set to “Mil on first error”...

As for the IAC cal, the procedure I show relies on good baseline data, as in VE or MAF are dialed in. It’s designed to mirror the dynamic airflow curve. These numbers, after set, will not match day to day. So once you have a stable and acceptable IAC curve for the flow of the new TB, leave it alone. You want your counts to be roughly 40-60 when hot. The purpose of the IAC, really, is to be able to stand outside the car, start it, and let it warm up on its own, with zero help. When cold the IAC should be able to open all the way up (to count 310) and provide enough airflow to keep it running.

Another thing that helps, and I do recommend this for the 102, is porting out the IAC air hole as much as possible on the back side. After I did mine on my Camaro I was able to get it to idle stable at 500-600 RPM, with 80# injectors, and a 244/252 .631/.631 114+4 cam. Those are the @ .050 numbers. It’s pretty narly lol. But porting it was clearly noticeable. Before lowest I think I could command was around 700 before it started surging due to IAC becoming unstable, obviously, because my MAP readings were pushing 80 lol. So inefficient haha.

I should also add, that with stock injectors, you may have to keep an eye on that duty cycle. I’m not sure what airflow you are seeing over stock, but the stockers are usually not up for the job after a few solid upgrades like cam, intake, heads, etc, especially 24#. Make sure to log injector duty cycle and watch for numbers over 90% or over 100, obviously. 90% is pushing it, though there are a few schools of thought on that. It’s better to simply have enough injector, but not too much, as that can cause its own problems, like having to scale after the fact due to maxed out airmass models.

**ChopperDoc** · 07-22-2020

Okay, had a chance to look at your tune and scans. Are you using a rail type fuel pressure regulator? I know it's a swap, so have to ask. If you don't have a rail type fuel pressure regulator, then the injector flow should be a slope, aka MAP based, and not flat lined. If you have the regulator from the truck, as it was stock, then disregard. Flat line indicates a rail pressure regulator.

The IAC counts look good, and the numbers are logical. They get down a little low, but idle airflow is not what is causing your rich condition. I see now you have the MAF failed, all adders are off, so VE tables should be your primary airmass model. Again, keeping in mind the "primary" VE table is still actually the secondary when the MAF is failed, on the stock OS.

You should see results when reducing the VE tables accordingly. Here is what I got after applying your AFR errors to the file...

This is the main table, errors applied and smoothed. I also carried the correction to the edge, by multiplying it by 80% and smoothing it in.

VE main with changes applied and smoothed..PNG

Here is the secondary table with rows copied from main.

VE Secondary with changes, copied from main.PNG

DO NOT forget to zero out the trims in the scanner. What I am showing here is an example, as results will vary after you zero out those trims. Do this first, re-log it, and apply the changes as shown. You will have to carry the number to the edge, and in this case I used 80% and it looked pretty good. I multiplied the 1600 RPM column by 95% and smoothed that into the correction as well. It should be a logical curve. Use your judgement here, make it look similar to these examples and life should be better. It will require tweaking after this, so but this is a better start than your second file there shows, as it looks pretty whacky in the change regions. Make sure you keep it smooth. A few small bumps and dips aren't a major concern, but if it looks like a rocky mountain skyline, there will be problems.

**ChopperDoc** · 07-22-2020

I just noticed in your log, that the MAF is still reading airflow. It should say zero. Unplug it if necessary, unless it has the integrated IAT. If this is the tune file that was in the PCM when logging, something is up with that. Also, as noted above, the DTC's are not showing in the scanner for the failed MAF. You should have some P101 codes. This is 100% the issue. Can't believe I didn't look at that sooner lol.

**sporkit** · 07-22-2020

Originally Posted by 5FDP

Computers that have both primary and secondary are different than computer with just a primary. You can upgrade your operating system to a speed density enhanced OS to remove the secondary table or keep it as is.

This was 100% my problem. The resolution on this table is so low I figured it was for some special situation. I copied the values over as suggested and was finally able to get my AFR to move.

Originally Posted by blindsquirrel

Where are you seeing the MAF codes set? Because there's none in the logs you posted.

I def verified the code was there at some point. Although, I think I cleared the codes when I did. Next drive I will double check on this. Also.. how are you checking the codes? I can only see this when I have the scanner plugged into the car.