Problem adding MAT to $0D TBI 7427, Not pulling timing.

[96lt4c4]

Part of the reason you get unexpected results is because the code in the 7427 is more complex than the simpler machines like the 747. This complexity increases on an order of magnitude when you get to OBDII and I can promise there are plenty of cases floating around where a newer pcm doesn't do as expected, either.

Sorry for the crickets. You're not the only one left playing with the old pcm's. I just don't have the time that I used to.

CPI trucks use air temp as a compensation. IAT or MAT, it's really no different from the ecm perspective. Sensor generates data, code responds (or doesn't). First, ensure the air temp sensor code is not a current code. ECM will fall back to default temp if there's an error. Then look for minimum temps to enable / disable compensation, or timers that have to expire before compensation begins. Are you certain that the definition file you're using is configured to display timing correctly? Did you notice any performance changes?

My tune is based off of the stock bin that came with the truck. 1994 TBI BJLF $0D. The base timing is set to zero and has been verified at idle with an adjustable timing light. The only initial performance changes I noticed when enabling the MAT was that, the truck fell on its face under boost from going extremely rich due to the MAT & CTS Blend Multiplier vs. Airflow table. I copied the table out of a stock CPI bin. The fix was to just enter all 1's in the table to make the PCM bias ECT instead of MAT. I think this would only have an effect on AFR and not timing, I may be wrong. I plan on looking at this again later, but for right now its working. The truck's VE tables are pretty close and I am getting the AFR I am commanding in the PE AFR table, under WOT, via my wide-band/boost controller.

I am 99% sure the timing I am logging and commanding is what the motor is seeing. I added a degree to the PE timing table, and the log shows 1 degree added to my timing table during PE. The test that I tried with the -10 degrees in the entire MAT Spark Advance Compensation vs. MAP vs. Temperature table did not pull any timing at all anywhere and did not change performance. Thats one of the reasons I used -10, because I knew I would be able to feel it happen but nothing changed. I may start looking back through the hack to see if I can find something that has been missed.

You are right about that code, when I noticed the overly rich condition and suspected the MAT, I unplugged it and the truck ran great, so that may be an old code.

There are the 2 MAT Spark multiplier, Neagtive and Postive, tables. The way I understand these are, there has to be a value in the table for the MAT Spark Advance Compensation vs. MAP vs. Temperature table to work. So if the negative and positive tables are zeroed out, it basically deactivates the MAT Spark Advance Compensation vs. MAP vs. Temperature table. So I have all 1's in from 55 KPA up to 100 KPA. Which in my case is actually 100 KPA up to 200 KPA, 2 BAR MAP for boost. I need to change my .xdf to show this. I have been trying to change tables to show the 2 BAR MAP readings as I come across them, just have not done these yet.

[1project2many]

It sounds like MAT is being used by the code so the question is why isn't spark changing. Check the two additional tables I mentioned. Are they included in your definition file? I haven't had a chance to try and work out how they are actually used but I'm sure they matter.

[1BadAction]

Did you ever figure out while your 80E was shifting soft?

I changed the voltage curve in the force motor tables to get the pressures in line with what was being commanded. I have about 15 thousand miles on it like that and works perfect.

IF (a big if) I do decide to go late model ECM/Trans control, I would either do it in conjunction with a fresh 80e and a triple disc converter, or the most likely scenario is I would use a MS3 Pro for engine control and a microsquirt trans controller, the microsquirt can be adjusted for any of the 80s, and can also be used to control up to an 8 speed, which would allow me to swap to an 8L90 in the future. The only thing I don't like about aftermarket is the fact that if one shits the bed, I'll be waiting a few days minimum to get another. That could be a huge problem if I'm somewhere away from home, and my truck is a driver not a weekend track vehicle.

Part of the reason you get unexpected results is because the code in the 7427 is more complex than the simpler machines like the 747. This complexity increases on an order of magnitude when you get to OBDII and I can promise there are plenty of cases floating around where a newer pcm doesn't do as expected, either.

Correct, but with a late model controller, you're paying for it to be supported by HPTuners and EFILive, there is no time where you are out hanging by yourself. If you have an issue all it takes is to ask there, and those guys will give you rock solid info, or they will take the time to figure it out. This isn't a bash against the guys who keep these old boxes alive and viable, I'm just saying that sometimes it gets old being 100% on your own with something that should be really simple.

If I could afford it I would be right there with you, but until then I gots what I got....

I figure its a lot cheaper than a new truck and can do the jobs I ask it without breaking a sweat. I hope to get paint on it before the winter rolls around but not sure if I'll have the time. I doubt I'll ever sell it after its painted.

[Nasty-Z]

I know if this gen VI timing cover fits on my gen V like I believe it will, I'm going to retrofit cam and crank sensors in and run a full sequential coil on plug setup.

It will not , even after drilling and tapping the 6 holes for the Gen VI cover (which can be done) , it will put the front seal in a different position than the Gen V cover . Some have grafted portions of a Gen VI pan to the Gen V pan to make it work , but it is a time consuming task.

Short of swapping to a gen VI block or aftermarket , there are these fine folks : http://www.eficonnection.com , but they seem to base everything on a Gen VI setup.


TOM

[bybyc5]

Every time the MAT subject comes up on here it goes about 4-5 post then dies. I'd really like to get in working in my truck but the first time I tried it my BLMs went nuts. Wish I had time to figure it out...

I'm guilty of this. I am wanting to add this to my 93 K1500 too. I see a post or two, and no real progress, then nothing. What searches I have done have been weak.

Any particular MAT sensor part number better than others?

[1project2many]

Correct, but with a late model controller, you're paying for it to be supported by HPTuners and EFILive, there is no time where you are out hanging by yourself. If you have an issue all it takes is to ask there, and those guys will give you rock solid info, or they will take the time to figure it out. This isn't a bash against the guys who keep these old boxes alive and viable, I'm just saying that sometimes it gets old being 100% on your own with something that should be really simple.

I can understand this. I'm used to being on my own so I guess I don't really think about it. It's good to get support when you need it.

[brian617]

I'm guilty of this. I am wanting to add this to my 93 K1500 too. I see a post or two, and no real progress, then nothing. What searches I have done have been weak.

Any particular MAT sensor part number better than others?

I used a 95 model 6.5L Diesel IAT.

[96lt4c4]

It sounds like MAT is being used by the code so the question is why isn't spark changing. Check the two additional tables I mentioned. Are they included in your definition file? I haven't had a chance to try and work out how they are actually used but I'm sure they matter.

Yes it looks like I have all those addresses populated in my .xdf file. I added the switch at $442f bit 1. The CPI bins had this set, TBI did not. I set it in my bin, still did not work.

[brian617]

My question has always been, what numbers go in this table? I understand it as a blend percentage, but what number is 100% MAT and what number is 100% CTS.

[96lt4c4]

My question has always been, what numbers go in this table? I understand it as a blend percentage, but what number is 100% MAT and what number is 100% CTS.

Its kind of hard to explain, but this is the way I understand it. The air moving through the intake at low speed, low air flow, has more time in the intake to heat soak and becomes the same temp as the ECT. As air flow increases, the air has less time to heat soak in the intake as it moves through, so you would in theory want the PCM to bias more toward the MAT sensor, while calculating AFR. This number is a multiplier I have all 1's in it currently, anything less than 1 will richen the mixture up.

Edit--I think I told you guys wrong here. Because of code 25 being set, the PCM was using -40 C as the intake air temp all the time. So this is the reason I was going extremely rich with anything other than 1 in this table. So 1 gives all control to the ECT and 0 gives all control to MAT. This is why anything lower than 1 in my tune at all was way rich, PCM using -40 C as temp to calculate fuel.

[1BadAction]

It will not , even after drilling and tapping the 6 holes for the Gen VI cover (which can be done) , it will put the front seal in a different position than the Gen V cover . Some have grafted portions of a Gen VI pan to the Gen V pan to make it work , but it is a time consuming task.

Short of swapping to a gen VI block or aftermarket , there are these fine folks : http://www.eficonnection.com , but they seem to base everything on a Gen VI setup.


TOM

guess the next step is to cut up the cast aluminum vortec cover and graft it on a cast GenV cover, or buy the distributor adapter and external reluctor.

[brian617]

Its kind of hard to explain, but this is the way I understand it. The air moving through the intake at low speed, low air flow, has more time in the intake to heat soak and becomes the same temp as the ECT. As air flow increases, the air has less time to heat soak in the intake as it moves through, so you would in theory want the PCM to bias more toward the MAT sensor, while calculating AFR. This number is a multiplier I have all 1's in it currently, anything less than 1 will richen the mixture up.

I understand airflow the same way, its the numbers (multipler) that doesnt make any sense to me. Example, how would you know how fast your'e going if your speedometer used chinese numbers lol. If anything less than one will richen the mixture, would numbers above 1 lean it out?

[brian617]

I understand airflow the same way, its the numbers (multipler) that doesnt make any sense to me. Example, how would you know how fast your'e going if your speedometer used chinese numbers lol. If anything less than one will richen the mixture, would numbers above 1 lean it out?

This is hurting my brain, but I think if 1 is no blend from CTS to MAT and 0 is all MAT control? A number less than 1 wouldnt necessarily richen the mixture but give more control to the MAT which is typically cooler than the CTS. That sound right? Is 1-0 the only range of numbers?

[96lt4c4]

This is hurting my brain, but I think if 1 is no blend from CTS to MAT and 0 is all MAT control? A number less than 1 wouldnt necessarily richen the mixture but give more control to the MAT which is typically cooler than the CTS. That sound right? Is 1-0 the only range of numbers?

I have not tried anything over 1, I think the issue I am having is that a turbo really heats the air up, even though I have an intercooler, I am probably still ingesting hotter air than an NA motor. I am seeing what I am comanding on my wideband so I am not really interested in going any richer than 11 - 11.5:1 AFR. I tried scaling the table from 1 at low air flow down to .75 at max air flow and it was still going pretty rich. You will just have to play around with it and see what works.

[brian617]

I have not tried anything over 1, I think the issue I am having is that a turbo really heats the air up, even though I have an intercooler, I am probably still ingesting hotter air than an NA motor. I am seeing what I am comanding on my wideband so I am not really interested in going any richer than 11 - 11.5:1 AFR. I tried scaling the table from 1 at low air flow down to .75 at max air flow and it was still going pretty rich. You will just have to play around with it and see what works.

What kind of intake air temps are you seeing under boost?