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Calling all pro obd1 tuner experts... I found something interesting!

dbrannon79

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Hey guys, I recently discovered something on my truck with the junk yard PCM from a 94 that sparked my attention. while out on the road and using my foot in the pedal I noticed my truck would get up and go, then suddenly fall flat on it's face and loose all boost pressure. I normally don't drive hard so it took me a while to notice this issue. I have also had quite an interest in learning to diy tune these old trucks. I finally got my hands on a prom programmer and all the adapters from Moates.

I pulled the prom from the 94 PCM and read the chip. prom code is BMRM 42510073 on the sticker. I opened it up in TunerProRT and started poking around.

when I opened up the boost map table my jaw dropped! this screen shot will speak for it's self...
1633660072485.png

I actually thought I had a bad read on the prom, so I re-read it several times and even tried reading it on another pc just to be sure. each time I was getting the same results. why the heck is the upper range on the APP percentage showing desired boost in the negative numbers!

I did the same read on my OEM 95 model PCM that has a BPAA 16216871 prom in it. here is the same boost table from it's data.
1633660334689.png

anyone have any ideas why the wired boost numbers?
 

Rockabillyrat

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Cool info. I've never played around with OBD1 tuning, but I've done alot of OBD2 diesel stuff.

Can you post a snap shot of the timing table? id like to see what that looks like for research purposes.
 

dbrannon79

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I have the files from both I can provide if anyone want them. I have taken the BPAA prom info and have been playing with the numbers in different tables. burned on a new re-writeable chip and have it in my truck testing out. I increased some on the boost numbers and some on fueling under load, it seems to have woken up the truck a bit. there is also a setting for PTO for both in park and in gear for the rpm. I believe this is for the high idle switch. I have not tested it out yet but it seems we can set different rpm's for both.

I can provide the data I changed also if anyone is interested. I will post up the table screenshots on what I played with later when I get off work.
 

dbrannon79

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Cool info. I've never played around with OBD1 tuning, but I've done alot of OBD2 diesel stuff.

Can you post a snap shot of the timing table? id like to see what that looks like for research purposes.
absolutely! Ill post up the tables after work today :)

the hardware I ordered from Moates wasn't that expensive ether. if you look on their site, I ordered the Burn2 programmer, G5 adapter, and the HDR5 adaptor. also a couple of the 27SF512 re-writeable chips.
 

Will L.

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WAY OFF TRACK. But want to ask while on my mind. Please say leave it alone if this will wreck your thread @dbrannon79 - And lets ask moderator to erase my post so it doesn’t wreck it if too late for me to.
Me and programming is oil and water. Is there programming that shows controlling the transmission you can do?

I realize BigT has obd2 and this is obd1. But I am wondering can programming be done to an ecm to just function transmission without making actual changes to fuel, boost,etc?
Like a person using their original ecm instead of a stand alone if they want to convert ds4 to db2? I think this is gonna become more required in time as ds4 is nla new and soon many will want the conversion. Many obd1 owners will have the dilemma too.
 

dbrannon79

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WAY OFF TRACK. But want to ask while on my mind. Please say leave it alone if this will wreck your thread @dbrannon79 - And lets ask moderator to erase my post so it doesn’t wreck it if too late for me to.
Me and programming is oil and water. Is there programming that shows controlling the transmission you can do?

I realize BigT has obd2 and this is obd1. But I am wondering can programming be done to an ecm to just function transmission without making actual changes to fuel, boost,etc?
Like a person using their original ecm instead of a stand alone if they want to convert ds4 to db2? I think this is gonna become more required in time as ds4 is nla new and soon many will want the conversion. Many obd1 owners will have the dilemma too.
no worries Will, yes there are tables in there for shift points and tcc lockup for 2nd through 4th gear. when I get home this evening I will post up different screenshots of the available tables and setting in there. if you download tunerpro or tunerproRT I can send you the files to play with. I got most of my info from another DIY tuning thread here in forums. a member I haven't see here in a good while "TheDrip' had hosted a file sharing site where I was able to collect some of the prom bins to get started. an another file I found on another forum that decodes the bin files that someone built which puts all the data into graphs and tables for us you'll need too. I'll freely share all of it. I just have to be careful because there were some copy righted stuff out there that caused an uproar. hopefully everything I have is "home" built and freely shareable! I just want to make sure I don't step on anyone's toes if ya know what I mean lol
 

Will L.

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Cool. I won’t personally get into it, so I don’t want you to do anything in an attempt of helping me. I am just thinking of something that ds4 owners here can use if they want to i. Order to eliminate the ds4 yet keep everything else active.

Like can a person just swap to db2, leaving ds4 unplugged and have transmission and everything else work normally? Or make programming changes to do that?
 

dbrannon79

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I think from what I have read, the chip can be programmed to use different logic to allow shifting. from my understanding if someone can read a prom ship from a stand alone trans controller and put it on a chip that goes into a standard PCM, it would work the same as a trans controller ignoring all the ds4 stuff on the engine. I may be wrong though!
 

dbrannon79

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some of the vendors here might even want to add one of those custom chips to their items for sale. it would be nice to have a "plug n play" item that would allow easier db2 conversions! I'll even volunteer to read a chip and post it up for anyone that wants it, if I can get my hands on a prom from a trans controller.
 

Big T

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Cool. I won’t personally get into it, so I don’t want you to do anything in an attempt of helping me. I am just thinking of something that ds4 owners here can use if they want to i. Order to eliminate the ds4 yet keep everything else active.

Like can a person just swap to db2, leaving ds4 unplugged and have transmission and everything else work normally? Or make programming changes to do that?
I’ve never seen someone work so hard to get a fellow board member a tranny conversion. You’ve lived in Vegas too long!
 

Will L.

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I’ve never seen someone work so hard to get a fellow board member a tranny conversion. You’ve lived in Vegas too long!
I know you want to join the bruce Jenner club! Haha.

I have seen these kind if things on older rigs before, where parts availability dries up- so I can see what’s coming in a few years.
 

dbrannon79

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well... I hope I'm not shooting myself in the foot lol but Challenge accepted! if someone can get their hands on a trans controller that has a removeable prom chip. and it's not gonna disable anyone's rig. I'll be happy to try reading the chip and post up results, maybe even burn the info to a PCM prom chip for someone to try in their db4 rig that has been converted to DB2!
 

dbrannon79

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ok guys, here are some screen shots of the timing, fueling, and trans tables. there is lots of other things too. almost too much to screenshot it all. these screenshots are from a stock BPAA 1995 prom chip data...

Timing tables
1633733758497.png
1633733811219.png
1633733828459.png
1633733841107.png

Fueling tables
1633733906250.png
1633733929107.png
1633733969830.png
1633734006083.png
1633734026100.png

More to come....
 

dbrannon79

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Ant more...

Cruise settings.
1633734591551.png

EGR settings... it has provisions but being this prom is vin F nothing is set. I need to get a bin file that has EGR setting to see what they actually are.
1633734726059.png

Trans settings..
1633734829521.png

1633734917647.png

1633735024066.png

Some of the data is incomplete, I think it's due to the XDF file I have that decodes the chip data is incomplete
the XDF tells the tunerpro software where to look in the bin file (data from prom chip) for the specific info.

More to come...
 
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