Adding MAT to 350 TBI $0D/7247

[woody80z28]

I've gone with Vortec heads on my TBI with a carb intake (no coolant passage under the runners) and headers (no heat pipe to air cleaner) so even with my AE dialed in when up to temp, in cold weather and especially with a cold engine I get a nasty lean stumble on accel. When I add AE, I get a rich bog when up to temp at moderate ambient temp.

So...the plan is to add a MAT sensor and more AE when the manifold temp is very cold. I bought a MAT from Napa to go in the #8 runner (#ECH TS5100) http://napaonline.com/Catalog/Catalo...RecType%3aA%29 and modified a CTS plug to wire it in.

From what I read, 1 wire goes to pin B-9 and the other to ground. I grabbed the BPLH 4.3 bin from here and copied these settings:
MAT Sensor flag
Error 23 Low flag
Error 25 High flag
MAT Spark vs Vac vs Temp table
MAT Spark Multiplier vs MAP
MAT/CTS Nultiplier vs Airflow
TPS Difference AE Correction factor vs MAT

I dont know if anyone else here has done this yet, but I'm gonna wire it in soon and see how it works. If you have any tips/tricks I should know about before I do it, give a hollar. I have a 1-mile drive to work and the lean stumble during cold mornings drives me nuts! haha

[JeepsAndGuns]

I dont have any info that can help, but I will be watching this thread and watching your results closely. If it goes well, works, and you have good results, I may add one to mine.

[PJG1173]

I'm watching this one too.

[EagleMark]

So the option is in $OD but never came on a truck? I think I have seen it in my sons $OE we are doing right now and wanted to add this.

I had a 1993 Caprice 9C1 option cop car (NotaCop) 1228746 ECM I think and it ran well, got great fuel mileage compared to TBI trucks I have had without but I attributed that to aerodynamics? It is another measure of further calculating mixture by adding air desity so I don't see that as a bad thing.

Now IAT and MAT are very different and location of MAT can change temps dramatically, so need to see what bin says for temps and check location of MAT mounting in intake manifold. Where were MAT sensors placed on car engines then? Since truck did not have it? Strange it is in bin?

IAT would be in air coming in engine and less temp, closer to ambient temps. The old caprice above and my LT1 are both IAT. MAT, Manifold temps are much hotter. I am curious what scalers and tables or? say for adjustments...

[gregs78cam]

"Title: MAT Sensor
Location: 400B-Bit 6
Usage: Air Fuel Mode Words
Tips: Enables MAT sensor calibrations. Checkmark to enable MAT sensor calibrations. This can also be used for a IAT sensor. "

And I would think that the two parameters that would have the most impact on fueling would be:

Title: MAT & CTS Blend Multiplier vs. Airflow
Location: 4AE1
Usage: BPW Parameters
Tips: Larger multiplier = more CTS blended into MAT. Used only if L400B Bit 6 "MAT Sensor" is enabled.
Conversion: Multiplier = X / 128

Title: TPS Difference AE Correction Factor vs. MAT
Location: 4B80
Usage: Acceleration Enrichment Tables
Tips:
Conversion: Factor = X / 128

Now these are for $0E, but $0D should be the same, in almost the same location. I wouldn't necessarily say that MAT temps would be hotter, but they would vary over a much LARGER range.
In TP go over to tools and click on "parameter finder". type in MAT.

[EagleMark]

MAT temps are much hotter than IAT temps. I've done this research.

Now didn't you just find some diesel boost error codes in this PCM too? Well guess what? 1995 6.5L turbo diesel has a MAT when I looked it up on Rock Auto. You can tell by the way they mount they go into intake manifold.


The only other sensor for that year period, so far I can find is all IAT sensors which usually look something like this and go in incoming air tube usually air cleaner or tubing from MAF.


I'll go one step further and say that you can use a CTS which is way cheaper because the ohm meter tests are identical. But response time from CTS is not as fast. But half price and last forever in air... I already did that years ago with a 1228746 ECM conversion on a Scout II.

[JeepsAndGuns]

I'm cheap, so I would probably go grab a couple of the IAT's from the pull a part with their connectors. I remember seeing crapload of them on diffrent GM cars while going through there the last time.

One thing that makes me interested, is woody's discription of his engine. My MPFI intake does not have a exhaust crossover like my old one does, plus I am seriously concidering a set of headers after seeing a back to back dyno run with stock manifolds and two diffrent types of headers.

[PJG1173]

So the option is in $OD but never came on a truck? I think I have seen it in my sons $OE we are doing right now and wanted to add this.

I had a 1993 Caprice 9C1 option cop car (NotaCop) 1228746 ECM I think and it ran well, got great fuel mileage compared to TBI trucks I have had without but I attributed that to aerodynamics? It is another measure of further calculating mixture by adding air desity so I don't see that as a bad thing.

Now IAT and MAT are very different and location of MAT can change temps dramatically, so need to see what bin says for temps and check location of MAT mounting in intake manifold. Where were MAT sensors placed on car engines then? Since truck did not have it? Strange it is in bin?

IAT would be in air coming in engine and less temp, closer to ambient temps. The old caprice above and my LT1 are both IAT. MAT, Manifold temps are much hotter. I am curious what scalers and tables or? say for adjustments...

the 93-94 CPI 4.3L found in S10's and blazers had a MAT using $E6 and $0D. I'm still trying to get the basics down before venturing into this. I have been courious about this for a while since I am in the same boat. aftermarket intake with no crossover under the plentum. I've noticed this motor is sensitive to changes in temperatures and was hoping I could use this to counter that. BTW what is the BCC for the cop car option? I have a set of cop car injectors I'd like to lookup the settings for.

[EagleMark]

I'm cheap, so I would probably go grab a couple of the IAT's from the pull a part with their connectors. I remember seeing crapload of them on diffrent GM cars while going through there the last time.

One thing that makes me interested, is woody's discription of his engine. My MPFI intake does not have a exhaust crossover like my old one does, plus I am seriously concidering a set of headers after seeing a back to back dyno run with stock manifolds and two diffrent types of headers.

That exhaust crossover is to help engine and intake warm up faster for drivibuity. The crossover works in conjunction with heat riser valve in one side of V engine that is closed when cold, spring loaded and forces exhaust through intake. Opens when hot.

Another thing that is part of that and could help you guys is a hot air tube off header to intake. GM designed air filters are plentiful that require no valve or vacuum hoses. It sucks hot air when cold and opens when warm. Helps engine run better when cold but was installed to prevent icing of TB or carb back then...

Dyno numbers are WOT high measures of HP and tourqe. So yes you can get more at WOT high RPM but you give up drivability in all situations except 1/4 mile...

the 93-94 CPI 4.3L found in S10's and blazers had a MAT using $E6 and $0D. I'm still trying to get the basics down before venturing into this. I have been courious about this for a while since I am in the same boat. aftermarket intake with no crossover under the plentum. I've noticed this motor is sensitive to changes in temperatures and was hoping I could use this to counter that. BTW what is the BCC for the cop car option? I have a set of cop car injectors I'd like to lookup the settings for.

Thanks I'll look one up.

I don't remeber the bin to TBI 9C1 Cop car, it was in a laptop lost with coffee through keyboard incedent... the 9C1 RPO code option was so much more than just bigger injectors! Cool Car! I miss NotaCop...

[woody80z28]

I love this site already! Glad to get some more brains on this subject.

I looked at IAT vs MAT and decided on MAT for a couple of reasons. The TBI runners are wet flow, so the atomized fuel also plays a part in the air temp. I read (I think on TGO) that TBI runners under certain circumstances can actually be 20-40* colder than ambient temp...and the runners are right where the fuel wants to stick to when cold, so that's gotta be the best place to get a reading.

IAT seems like a better match for MPFI engines where the runners are mostly dry and the fuel does not skew the air temp. (My Beretta is MPFI/IAT.)

[woody80z28]

I'm cheap, so I would probably go grab a couple of the IAT's from the pull a part with their connectors. I remember seeing crapload of them on diffrent GM cars while going through there the last time.

One thing that makes me interested, is woody's discription of his engine. My MPFI intake does not have a exhaust crossover like my old one does, plus I am seriously concidering a set of headers after seeing a back to back dyno run with stock manifolds and two diffrent types of headers.

I think a MAT would be more functional than IAT, but that's another option to try and test.

My setup, from a cold-drivability standpoint is a big step back from stock I've come to realize. Stock TBI has the exhaust through the intake to the EGR and a coolant passage under the runners with a heater pipe from the exhaust to the air cleaner. I have none of that. I assume this is why the MAT wasnt needed stock and mine is a bear.

[EagleMark]

IAT seems like a better match for MPFI engines where the runners are mostly dry and the fuel does not skew the air temp. (My Beretta is MPFI/IAT.)

That would seem to be correct and I agree that MAT could be better choice. But my 1993 TBI car had IAT. But id had exhaust crossover, heat riser and hot air tube, stock! Your's I believe would be better with MAT because of all those things removed.

The programming of parameters used would be different for both I assume because temps would be different. Although tests I have done show ohm readings same as coolant CTS sensor. So it's what the ECM/PCM is programmed to do with that reading.

[gregs78cam]

I think a MAT would be more functional than IAT, but that's another option to try and test.

My setup, from a cold-drivability standpoint is a big step back from stock I've come to realize. Stock TBI has the exhaust through the intake to the EGR and a coolant passage under the runners with a heater pipe from the exhaust to the air cleaner. I have none of that. I assume this is why the MAT wasnt needed stock and mine is a bear.

That's the way the Camaro is, 2 TBIs on a RPM AirGap manifold. I just don't know if I will get the MAT sensor put in before I go MPFI, or not.

[EagleMark]

G1 has brought up another point. Does the intake have somwhere to put a MAT sensor? If not you need to drill and tap, with manifold off and big job.

But in thinking this through intake manifold temps are differant/higher than IAT temps becuae the intake is bolted to engine, engine is behind radiator getting warm, attached to heads etc... but you guys have eliminated major heat sources like exhaust heat crossover, EGR into intake and coolant passages? So not even coolant flow now?

So MAT are probably a lot closer to IAT temps. Without a place to put MAT sensor then IAT would be better than nothing and in your cases not as far off as regular engine.

So it boils down to what the mask has in it's paremeters it's looking for and adjusting to.

[EagleMark]

I was just looking through $OE and found "MAT & CTS Blend Multiplier vs. Airflow" since we have been told CPI uses MAT sensor, does it also use MAF sensor? In V8 TBI it is set to all 0s. So would have to know what vs. Airflow is?

Now this one looks promissing for AE which seems to be issue with cold engines. In V8 TBI $OE it is set to all 1.0 for all temps.
"TPS Difference AE Correction Factor vs. MAT"