LBZ ECM & LMM EGT sensors

[Cougar281]

I believe I had brought up the subject of connecting LMM EGT probes to a LBZ ECM some time back, and no one really knew, but the thought was that since the LBZ trucks didn't come with EGT sensors, the ECM simply wouldn't support them.

Well, I finally got a little motivation up to do a few minutes of tinkering. I set up a LMM ECM on the bench and connected two sensors up to it to verify proper connectivity. The sensors properly read the approximate air temp. I had selected the 'CATEMP11', 'EGT1A', 'CATEMP12' and 'EGT2A' PIDS for the E35B controller. 'CATEMP11' and 'EGT1A' matched each other, as did 'CATEMP12' and 'EGT2A'.

I then shut down the LMM ECM and connected up the LBZ ECM. First test was using the PSL for the E35B - this resulted in the 'EGT1A' and 'EGT2A' being invalid and disabled - but 'CATEMP1' and 'CATEMP2' remained valid - and gave data! (Other than -40F or open circuit). the problem is, the data is wrong. At rest, they read 133F or so, and when I breathed on a probe, the temp registered went down (An action that resulted in a brief increase in the LMM ECM).

Obviously, the ECM is capable of reading data from the probes - it would seem to be a scaling issue - Is there any chance you guys could add the ability to modify the scaling (or maybe someone with the knowhow can write a CAX file to add it)? I would think this would be really useful for those of us that would like to log the EGTs without the need to get an expensive external controller...

My next test might be to connect probes up to the EGR Temp Sensor pins - the problem being I don't know how I'd verify if they actually read anything as there don't seem to be any PIDs that would be related for the LBZ.

[GMPX]

It may go deeper than that, they may not have the rescaling routines for the PID's set up, it is a big task once you get down to this level.

[Cougar281]

So I guess the question is how hard would it be to determine if it's just a table or switch that's not set right for the sensors which, if exposed, could correct it, or something deeper that's difficult or impossible to fix?

[KB3MMX]

Going a little off topic here but it sure would be nice to have a fueling control table that references the EGT probe's temps.

[GMPX]

So I guess the question is how hard would it be to determine if it's just a table or switch that's not set right for the sensors which, if exposed, could correct it, or something deeper that's difficult or impossible to fix?

I don't know, probably very hard, I've never looked in to such a thing.

Going a little off topic here but it sure would be nice to have a fueling control table that references the EGT probe's temps.

Sorry, won't happen.