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

[96lt4c4]

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

Depends how hot it is outside, most I have seen so far is 160*F. Its been pretty cool here for the last couple weeks so they have been running in the 100-120 degree range. I just installed a Meth Injection kit so that will help cool them down under boost. Have not had a chance to run it yet.

This truck has become a plumbing nightmare..LOL

As far as the "Old PCM" comment. It really is amazing what I have been able to do with the stock PCM in this truck. For what it is, its a really powerful PCM that allows you to do a lot of stuff. For one I do not know of anyone running one with boost and a 2 bar map. I was told it could not be done, or that it would be hard to make it work. I have been messing with this thing since February and I have it running great, granted I had to build a new motor, but just learned the hard way.

[bybyc5]

Wow. Nice work. Way to stick with it and get it done! Just how much boost are you able to get?
One really nice feature with these older Chevy's is plenty of room under the hood!! Unlike many other vehicles...like our F-Bodies..Ha Ha. At least the corvettes have a fold up front cap.

Kudos

[96lt4c4]

Wow. Nice work. Way to stick with it and get it done! Just how much boost are you able to get?
One really nice feature with these older Chevy's is plenty of room under the hood!! Unlike many other vehicles...like our F-Bodies..Ha Ha. At least the corvettes have a fold up front cap.

Kudos

Thanks, right now I am at 8 psi, just changed my waste gate springs, should go up to around 10 now. I wont go any higher than 15 when its all said and done. There are guys getting 15 on 6 liter LS motors with this same turbo. Its a blast to drive on 8 pounds, talk about a sleeper...LOL. Yeah this may be my Guinea pig for my F Body. If I do decide to turbo the Camaro, it will get twins, on E85, should make 1000 HP no problem.

I think I found my problem, was looking through the hack last night and found about 5 MAT thresholds that need to be changed in order to keep code 25 from setting. There is a HI Temp setting that will set code 25, which in my stock TBI bin is set to -40 degrees C. Which in turn effects the Default MAT temp if error 23/25 setting, which is set to -40 degrees as well. So since I have code 25 set, the PCM is using -40 C for MAT calculations. Changing this to match a CPI or 4 cylinder s-10 bin should fix it.

Here is a screen shot, and I attached an updated .xdf file below. Hopefully this works and can help others who want to add MAT.

[1project2many]

Good work finding these. I caught something yesterday and ended up spending all night shivering under blankets.

So since I have code 25 set, the PCM is using -40 C for MAT calculations.

I thought you said you could see MAT on the scantool? You would see -40C if it went to default temp.

[96lt4c4]

Good work finding these. I caught something yesterday and ended up spending all night shivering under blankets.



I thought you said you could see MAT on the scantool? You would see -40C if it went to default temp.

That is true, the MAT shows the correct temp. If you download and watch a little bit of the log I posted in the first post, you can see that code 25 is set, but the MAT is still showing the correct temperature. Maybe that's why I have no light on...LOL. Either way my bin is set to -40 C as the "HI" temp that would set 25, so I know for sure that is not right. We will have to see what happens when I get a chance to change it, and drive it. Hopefully this is the fix.

[96lt4c4]

Its fixed! That did it. I am going to have to go back and look at the CTS and MAT blend table.

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.

Just looking around and found a thread on Fullsize chevy talking about adding MAT.

http://www.fullsizechevy.com/forum/g...-sensor-7.html

Basically anybody that has added MAT to a TBI bin, and did not fix the code 25 issue, is not getting correct fueling.

[brian617]

Its fixed! That did it. I am going to have to go back and look at the CTS and MAT blend table.

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.

Just looking around and found a thread on Fullsize chevy talking about adding MAT.

http://www.fullsizechevy.com/forum/g...-sensor-7.html

Basically anybody that has added MAT to a TBI bin, and did not fix the code 25 issue, is not getting correct fueling.

That does sound like the problem, now I have to figure out how to add those items to my XDF

[96lt4c4]

That does sound like the problem, now I have to figure out how to add those items to my XDF

I did it for you man! A couple posts up. My .xdf is setup for boost, but you can still use it to change the settings in your .bin file.

[brian617]

Thats cheating lol. I'd like to learn how.

Catch a fish for a man and he can have one meal, teach him how to fish and he wont go hungry?

[brian617]

I'm also using $OE, so locations are different.

[1project2many]

Hmm... I still haven't had time to look at the logs. I'm surprised the ecm was sending actual MAT on the ALDL but using a different value internally. That's not typical behavior.

Catch a fish for a man and he can have one meal, teach him how to fish and he wont go hungry?

Not quite. There's the gear and tackle, the bass boat and trailer, the truck to haul the trailer, electronic gadgets, videos, club memberships and numerous other expenses. But it does generate some good stories!

[96lt4c4]

Hmm... I still haven't had time to look at the logs. I'm surprised the ecm was sending actual MAT on the ALDL but using a different value internally. That's not typical behavior.



Not quite. There's the gear and tackle, the bass boat and trailer, the truck to haul the trailer, electronic gadgets, videos, club memberships and numerous other expenses. But it does generate some good stories!

It is definitely working now, as far as timing goes. I am going to start with the CPI Blend table and see what happens to my AFR. ON the drive in to work this morning I still had it set to all 1's. If it goes back to being way rich then I will know.

I just thought of something, me being the anal guy that I am, checked error 23 and 25 in my bin. I am wondering if you left those off, but still turned on the MAT, if this issue would even come up. A good possibility that most guys just turn on the MAT and do not mess with the error codes?

[brian617]

It is definitely working now, as far as timing goes. I am going to start with the CPI Blend table and see what happens to my AFR. ON the drive in to work this morning I still had it set to all 1's. If it goes back to being way rich then I will know.

I'm curious, if you give MAT full control of fuel, what tables are now responsible for adjusting fuel?

[96lt4c4]

I'm curious, if you give MAT full control of fuel, what tables are now responsible for adjusting fuel?

The 4 cylinder s-10 bin pretty much does just that. The CPI 4.3 gives more to ECT around idle and blends down to MAT. I read the thread on fullsize chevy about giving MAT full control, which with my setup sounds ideal, MPFI with MAT in the intake.

[brian617]

I tried that link, no worky.