Been alot of talk about MAT sensors recently. I have mine relocated in the airbox. Since I run the Miniram currently I don't have much choice. Now that I made the commitment to try my old ported Super Ram on my 396 mighty mouse, Should I put the MAT back in the plenum or leave it in the air box?

Jason BTW, I run the 7730 ECM

 

If you adjust the MAT Inverse Delta Tables in the SD eprom, I am finding a relocated MAT in front of the TB gives the best results with SD (only). The MAT Inverse Delta Tables on the SD 7730 provide correction factors for different readings of the MAT.

Since the stock MAT Inverse Delta tables were setup for an MAT located in the plenum, it is expecting higher MAT readings due to the intake, coolant in the TB and heat from the EGR entering the intake. The lower MAT readings from a relocated MAT result in the mixture being too rich. You must lean out the MAT Table to get a proper correction with a relocated MAT.

Also, EGR operation is affected as the stock "EGR Enable Temp" is around 5*C (40*F). With the stock MAT, the extra heat of the intake and EGR required an ambient air temperature of less than -20*C/-4*F before it caused the MAT temp to reduce itself below 5*C/40*F, and disable the EGR.

With my relocated MAT I had to lower my enable temperature if I didn't want my EGR to disable at a real ambient air temperature of only 5*C/40*F. Of course, if you don't have a functioning EGR, this is a non-issue.

This table does not exist in the MAF 165 ECM, so a relocated MAT does not appear to have the same affects on temperature corrections as SD. The MAF 165 does have the same EGR issues though.

As for how other cars use the MAT, see Grumpy's MAT - Final Answer post. The MAT has a different effect again on GNs. The MAT function varies greatly from ECM to ECM.

[This message has been edited by Glenn91L98GTA (edited August 15, 2001).]

 

First off, I agree 100% with what Glenn said.

To just continue a little.
You can use GM engineering to help you, or rewrite what they have done. When you sit down, and really study what they've done, it usually hard to outdo them.

The MAT corrections, seem to be more of a fudge factor then an specific correction.
From calibration to calibration, it varies in how they use it so that hints very strongly that it's a fudge item.

In some recent testing I've done I've seen where I can diddle the MAT with timing changes that are so slight that the Coolant temp doesn't change, but the MAT does, and in my case MPG increased. Everything else stayed the same, O2 voltage etc., and yet with no table corrections based on MAT the engine ran better. It takes miles for temps to stabilze when playing with 2d timing changes at cruise. You sometimes have to get really obtuse to get to the bottom of what's really going on.

 

I agree with Glenn...I am running a MAP setup and I just finished ram air setup along with the TB bypass. My scan tool is reporting air temps near 100*, it was around 120ish before I mess with it. Hopefully I can make the difference up in the bin? Or just undo my ram air setup till I understand the total effect of this change??

------------------
1988 L98
Vette Heads/no EGR
SLP Headers/Y-Pipe
ARAP bin

 

Opps I mean MAF..

 

Can you point out to me where in Tunerpro this is located?