MAF wont fail for VVE tuning

[2007chevy5.3l]

Okay, followed the tutorial, unplugged the yellow wire and it wont run. Go ahead, make me feel stupid...
What am I missing guys?

07 Tahoe 5.3L, CAI/Longtubes


Tahoe Speed Density VVEfilive.tun

[GMPX]

Because you set the MAF DTC's to 'Not Reported', these need to still be enabled or the ECM won't switch to Speed Density mode because it never acknowledges the MAF has really failed and still attempts to run off a non existent MAF signal. By all means set the MIL to 'No MIL'.
Your other option rather than unplugging the wire is to set the MAF Diagnostic test fail parameters so the MAF will always fail.
So with the MAF still plugged in set as so:

{C0301} MAF Frequency High Fail 150 Hz
{C0302} MAF Frequency Low Fail 100 Hz
{C0303} MAF Frequency High Failures 1
{C0304} MAF Frequency High Passes 63
{C0305} MAF Frequency Low Failures 1
{C0306} MAF Frequency Low Passes 63
{C0310} MAF Test Min Runtime 1.0 Seconds
{C0311} MAF Test Min Voltage 8.0 V
{C0312} MAF Test Min RPM 300 RPM

What will happen here is the MAF will always produce a frequency over 150Hz with the engine running, so instantly the ECM will assume the MAF is faulty because of the value we put in {C0301} and so drop to SD mode.

Cheers,
Ross

[2007chevy5.3l]

Okay so when I log the MAF Frequency Hz will it still show a reading or will it be 0? Thats how I checked to see if the MAF was failed or not

[Taz]

If you setup your parameters for VVE tuning (disabled the MAF) per Swingtan's VVE Tutorial, or using the values Ross posted above, and you have a MAF DTC occurring (not a MIL light - this should also have been disabled - just the DTC itself set if you scan the ECM), then the ECM should have "Failed" the MAF. As long as the MAF is powered, and the signal wire is connected, it will continue to report data - but this will be ignored by the ECM.

To completely eliminate MAF input to the ECM - remove the yellow wire from the MAF connector plug - and reconnect the plug to the MAF (this maintains IAT data).

Removing the MAF signal wire (yellow) is also mentioned in Swingtan's tutorial.


Regards,
Taz

[2007chevy5.3l]

Oh okay I think I get what you are saying. Im going to try the settings Ross suggests and see if that works. I will report back later tonight when I have given it a shot.

Thanks Guys!

[2007chevy5.3l]

Ross, thank you for getting me straight on the MAF fail parameters. I tried them out and they worked great.


I did get a service traction control/stabilitrac light and I have the option of turing that off in B9901-B9902, after doin that it says "After applying this patch you must save the file, then perform a 'Full Flash' of the ECM". Does that mean I need to program the PCM with currently loaded operating system and calibration?

Second, My trans shift firmer in 1->2 shift at part throttle, much too firm in my opinion. So, will I need to lower the 1->2 base pressure upshift to compensate?

Lastly, What is an idea AFR, throttle and rpm for a "lean cruise"? I was seeing 15s-16s AFR at low cruise speeds and to me that seems a bit too lean. Any advice?

Here is my log without the MAF. The VE map is pretty rough
Tahoe NoMAF.efi

[Gregs]

Ross, thank you for getting me straight on the MAF fail parameters. I tried them out and they worked great.


I did get a service traction control/stabilitrac light and I have the option of turing that off in B9901-B9902, after doin that it says "After applying this patch you must save the file, then perform a 'Full Flash' of the ECM". Does that mean I need to program the PCM with currently loaded operating system and calibration?

Second, My trans shift firmer in 1->2 shift at part throttle, much too firm in my opinion. So, will I need to lower the 1->2 base pressure upshift to compensate?

Lastly, What is an idea AFR, throttle and rpm for a "lean cruise"? I was seeing 15s-16s AFR at low cruise speeds and to me that seems a bit too lean. Any advice?

Here is my log without the MAF. The VE map is pretty rough
Tahoe NoMAF.efi

1. yes

2. I would NOT change the 1->2 base pressure. "Vehicles equipped with automatic transmissions should go to table {E0104} “Transmission DTC Fault Pressure Modifiers” and set P0101, P0102, and P0103 to NO to prevent the PCM from increasing shift pressures."

3. lambda 1.05 or 15.4 if you are running non ethanol fuel, but as always this is a good starting point and you should adapt it for optimum results

[2007chevy5.3l]

1. yes

2. Its been a while so i don't remember exactly but i think i remember disabling a trans code and i think there was a pressure adapt table for when there is a maf failure. Sorry its been a while. I would NOT change the 1->2 base pressure.

3. lambda 1.05 or 15.4 if you are running non ethanol fuel, but as always this is a good starting point and you should adapt it for optimum results

Alright, I see how it likes 15.4 AFR. As of now its super lean. Im seeing 15.5-16.2 AFR at cruise. Definatly too lean but my VE is way out

[Gregs]

well its all just guesswork unless you have a dyno, for example on that graph it shows 12.6 afr as max power however the ideal afr is different for everyone so don't take the graph as the law.

[2007chevy5.3l]

Guess work it is! But I will be happy to have it atleast "close"

Thank You for finding the Trans pressure tables.