Odd 4+3 problem with custom chip - suggestions?
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 993
Likes: 4
From: Glen Burnie MD
Odd 4+3 problem with custom chip - suggestions?
This is a strange one. I've got an 86 with the 4+3 transmission, which according to 5speeds.com is the only year without a 1st gear switch - which makes it unique in that it's totally controlled by the ECU.
Anyway, I have a custom chip from Jeff DeBuhr that, when installed, will not allow the overdrive to work right. Jeff has looked over the BIN file and found nothing that he thinks is out of the ordinary.
The symptoms are that the O/D button on the stick will not work, and the car will shift OUT of overdrive at 25 mph, regardless of gear selected, and shift INTO overdrive somewhere around 80 mph, regardless of gear selected OR throttle input. Under light, normal driving, the OD engages as expected but won't disengage. Under hard acceleration, the transmission goes into OD around 80 MPH whether I want it to or not. Needless to say, that really screws with my 1/4 mile times... not to mention the shock to the drivetrain when I slow past 25.
The other chip that I have is an ADS SuperChip that was in the car when I got it. The OD works just fine with this chip.
Anyone got any ideas where to start looking? I've got the BIN file and TunerCat, but no idea where to begin for a problem like this.
Thanks much.
[RICHR]
Anyway, I have a custom chip from Jeff DeBuhr that, when installed, will not allow the overdrive to work right. Jeff has looked over the BIN file and found nothing that he thinks is out of the ordinary.
The symptoms are that the O/D button on the stick will not work, and the car will shift OUT of overdrive at 25 mph, regardless of gear selected, and shift INTO overdrive somewhere around 80 mph, regardless of gear selected OR throttle input. Under light, normal driving, the OD engages as expected but won't disengage. Under hard acceleration, the transmission goes into OD around 80 MPH whether I want it to or not. Needless to say, that really screws with my 1/4 mile times... not to mention the shock to the drivetrain when I slow past 25.
The other chip that I have is an ADS SuperChip that was in the car when I got it. The OD works just fine with this chip.
Anyone got any ideas where to start looking? I've got the BIN file and TunerCat, but no idea where to begin for a problem like this.
Thanks much.
[RICHR]
Melting Slicks
Joined: Aug 2003
Posts: 3,399
Likes: 395
From: Lakeville MI
Sounds like you have some issues with the new bin.
I have played with my 88 4+3 (ABTR based bin) quite a bit, and I am pretty familiar with the function and tuning of the 4+3.
It sounds like the forced shift is incorrect too low(80 mph this should be easy to fix) and there are also problems with your downshift vs tps tables. The n/v limits may also be wrong which messess up detection of first and 4th gear. Not sure about the switch not working???
I wonder if your bin and definition files match 32? or 32B?, It could be that your editing/viewing the wrong addresses. Any issues with your tach, speedo, tps or gearing?
I can look at the bin if you want. I don't want to step on anybody's toes, but I am willing to help if I can.
I have played with my 88 4+3 (ABTR based bin) quite a bit, and I am pretty familiar with the function and tuning of the 4+3.
It sounds like the forced shift is incorrect too low(80 mph this should be easy to fix) and there are also problems with your downshift vs tps tables. The n/v limits may also be wrong which messess up detection of first and 4th gear. Not sure about the switch not working???
I wonder if your bin and definition files match 32? or 32B?, It could be that your editing/viewing the wrong addresses. Any issues with your tach, speedo, tps or gearing?
I can look at the bin if you want. I don't want to step on anybody's toes, but I am willing to help if I can.
Thread Starter
Burning Brakes
Joined: Jan 2002
Posts: 993
Likes: 4
From: Glen Burnie MD
I can email you the binary; Jeff's probably spent more time working on my chip than he wants... my near-term goal is to get a PROMinator and save him the trouble until I need one final one burned.
Anyway, AFAIK the tach and speedo are right. I get consistently better gas mileage than with the "stock" chip, but put that down to the new burn and the cam. I'm still learning how to read the bin file, so any pointers would definitely be appreciated.
I thought about the forced-shift; doesn't that usually take place at 124 mph? Jeff said he didn't change any of the O/D values from stock.
Let me know if you want the file.
Thanks.
[RICHR]
Anyway, AFAIK the tach and speedo are right. I get consistently better gas mileage than with the "stock" chip, but put that down to the new burn and the cam. I'm still learning how to read the bin file, so any pointers would definitely be appreciated.
I thought about the forced-shift; doesn't that usually take place at 124 mph? Jeff said he didn't change any of the O/D values from stock.
Let me know if you want the file.
Thanks.
[RICHR]
