fieroguru

iTrader: (1)

A couple weeks ago, I did the LS7 MAF upgrade on my LS4 and immediately noticed that the intake air temp being scanned jumped quite a bit. In my install, the exhaust does not pass under the air intake, so it doesn't see much higher temps than ambient under most situations. However, when I was logging with the LS7 MAF (and its IAT sensor), I was reading 111 degrees on a mid 80 degree day while driving at highway speeds. On a first start of the day when it was 65ish degrees out, it was showing 95 degress before the car was started and 85 once air was moving through the tube.

The real issue with this is the temps it was reading was pulling 5-6 degrees of timing and hurting performance.

When I compared the IAT tables between the E67 LS4 and the LS7, the entered values were exactly the same, but the scale (ohms) for each row was significantly different. So I put both tables in excel and found the proper values for the LS4 e67 scale to read the appropriate temps with the LS7 MAF. Below is a picture with the stock LS4 values for both E40 and E67 versions, the LS7 values and the modified tables for both the E40 and E67's. You will notice that even the two stock LS4 tables are different.

smoooth

I've just started reading on the MAF change, so forgive me if I sound uninformed but I have some questions.....With the chart you have, are you able to calibrate the MAF readings to make it read accurately? Have you noticed any improvements with the new MAF (enough to make the change worthwhile)?

The reason I ask is after reading some of the other threads on this mod I’ve started looking for the necessary parts to make the swap, but my programmer is skeptical that it will make any difference.

What you posted is GREAT information. Thank you for sharing your work!

fieroguru

iTrader: (1)

If you use the modified numbers in the chart for the specific ecm, then the ECM should report the actual air temp with the LS7 MAF.

As far as the upgrade, I was already running the 85mm MAF and pulling about 4kpa vacuum at WOT at 6800 rpm (224/232 camshaft). Changed the 4" LS7 MAF and I am still pulling about 4kpa at WOT at 6800 rpm, so it didn't help me much, besides confirming that the air intake setup is essentially restriction free up to the 90mm throttle body.

If you are running the stock MAF, then the upgrade to the LS7 or even just to the 85mm will be a significant improvement, but only if you have done other improvements including an intake manifold upgrade.

nmp0098

You should actually just edit the axis. Some of the axis tables are editable, some are not. This one is. I also find modifying the idle control axis (minimum airflow and torque follower are linked) and the pedal to throttle mapping axis to be useful.

fieroguru

iTrader: (1)

Guess I did it the hard way again...

Thanks for the tip on changing the axis values, didn't know that was possible.

severancej

Bumpin