Full line pressure with A4 SD tune

[jnorris]

A few nights ago I flashed in a SD tuning file using EFILive/AutoVE Tuning guide in my 98 Z28 with an A4 transmission and have a problem.

The PCM is commanding full transmission line pressure at all times. All shifts are very harsh. I checked the transmission DTC fault enablers for P0101, P0102, and P0103 and they are set to “No”
The Engine DTC MIL Enablers for these codes are set to “No MIL” per the EFILive/AutoVE Tuning guide.
What can I do to prevent the PCM from commanding full transmission line pressure on all but heavy/full throttle shifts?

Thanks

John

[joecar]

Disable P0101, P0102, P0103 in the following table: E0102 (Trans. DTC Max Pressure Enablers).

[jnorris]

Disable P0101, P0102, P0103 in the following table: E0102 (Trans. DTC Max Pressure Enablers).

I checked that and they were all already set to "NO". What is strange is that I thought these were set as "YES" in the stock tune. I never changed them to "NO":confused:


John

[Black02SS]

I would like to know this as well as I have experienced this on a few cars.

[Black02SS]

Ross or Paul.........Any update or suggestions?

[GMPX]

No further suggestions, I thought that would cure it which is why we put that table in, I'll look into what else may cause it.

Cheers,
Ross

[Black02SS]

Oh. Keep us updated if you find anything else. :bawl:

[GMPX]

Just a thought, log PID 'GM.TSTATE07' and look to see if the PCM is flaging full line pressure due to a DTC being set.

Cheers,
Ross

[jnorris]

Just a thought, log PID 'GM.TSTATE07' and look to see if the PCM is flaging full line pressure due to a DTC being set.

Cheers,
Ross


Done.

Below are the codes with the SD tune in the PCM and the MAF unhooked. At idle the trans pressure was 30psi in neutral and 35 psi in drive.
P0102 "Mass Air Flow (MAF) Sensor Circuit Low" EPA Pending ($10) "Powertrain Control Module (PCM)"
P0102 "Mass Air Flow (MAF) Sensor Circuit Low" PC ($10) "Powertrain Control Module (PCM)"


Below are the codes with the SD tune in the PCM and the MAF hooked up. At idle the trans pressure was 30psi in neutral and 35 psi in drive.
P0102 "Mass Air Flow (MAF) Sensor Circuit Low" EPA Pending ($10) "Powertrain Control Module (PCM)"
P0103 "Mass Air Flow (MAF) Sensor Circuit High" EPA Pending ($10) "Powertrain Control Module (PCM)"
P0103 "Mass Air Flow (MAF) Sensor Circuit High" PC ($10) "Powertrain Control Module (PCM)"

With the MAF tune in the PCM the trans pressure was at zero psi in neutral and 5psi in drive.
Maximum pressure due to MALF (TSTATE08-MAXPRES) was at “NO” during all tests.

John

[joecar]

30/35 psi is not max line pressure, but is somewhat high for idle (expected is 5-10 psi).

It seems as if the PCM is modifying line pressure based on airflow... BUT there appears to be no table for this.

[GMPX]

Maximum pressure due to MALF (TSTATE08-MAXPRES) was at “NO” during all tests.

John

Thanks John, I won't bother chasing it down that way then.

Cheers,
Ross

[jnorris]

30/35 psi is not max line pressure, but is somewhat high for idle (expected is 5-10 psi).

It seems as if the PCM is modifying line pressure based on airflow... BUT there appears to be no table for this.

It is max pressure for the amount of engine torque that was being measured by the PCM at idle.

John

[joecar]

It is max pressure for the amount of engine torque that was being measured by the PCM at idle.

John I'm sorry I don't follow, please explain further...

Joe

[jnorris]

The transmission line pressures are set by the values in {D0701} and the other tables under the “Trans Pressures”

John

[Black02SS]

Don't know if it helps any. Did two A4's today, one a 00 and the other a 01. I didn't have a problem with either of them.

[dissonance]

Don't know if it helps any. Did two A4's today, one a 00 and the other a 01. I didn't have a problem with either of them.

from what my own car "98" and what others have reported this is only a 98 related problem. i gave up on the SD tune for now because the last thing i need is for my trans to have problems "again"

[Black02SS]

from what my own car "98" and what others have reported this is only a 98 related problem. i gave up on the SD tune for now because the last thing i need is for my trans to have problems "again"
I have personally seen this on a 99 and 00 as well. :bawl:

[dissonance]

i see what you mean, maybe this is a diffrent problem but alot of guys on tech have found ways to fix it but all the fix's are for 98 cars. it was sometime ago but i was not able to match up all the changes that needed to be made with flashscan. most fix's are step by step hptuners. maybe someone alittle smater then me could put two and two togeather.

it's a maf code related fail safe mode? only with the maf unplugged right not just the fail feq turned down?

i will see if can find some of the info i was working with before.

[Black02SS]

it was sometime ago but i was not able to match up all the changes that needed to be made with flashscan. most fix's are step by step hptuners. maybe someone alittle smater then me could put two and two togeather.

also is this only with the maf unplugged right? it's a maf code related fail safe mode?


Back when I was a HPT customer :bawl: the only way I knew to fix the problem, was to send the bin in and have them "fix" it.

[jnorris]

For what it is worth went to {C6001} Engine DTC Processing Enablers and I changed P0101, P0102, and P0103 to "X:Not Reported" from “B: 2 Trips, Emissions Related” and the car would not run. It would crank but not start.

[dissonance]

Back when I was a HPT customer :bawl: the only way I knew to fix the problem, was to send the bin in and have them "fix" it.

do you still have these bin files? before and after the work... should be easy to track down if you do. :cheers:

[Black02SS]

For what it is worth went to {C6001} Engine DTC Processing Enablers and I changed P0101, P0102, and P0103 to "X:Not Reported" from “B: 2 Trips, Emissions Related” and the car would not run. It would crank but not start. When that happened, more then likely the car ran super lean. What I have noticed when turning the codes to X Not Reported, the car didn't fault into Speed Density and still used the MAF table for partial fueling. I have mine in all the cars set to 1 Trip/No Mil

[Black02SS]

do you still have these bin files? before and after the work... should be easy to track down if you do. :cheers:
Nope, sure don't. Lost the HD and everything on it.

[jnorris]

do you still have these bin files? before and after the work... should be easy to track down if you do. :cheers:

Per gameover on LS1Tech:

"the bits i change are just the P101,P102,P103 bits."


http://www.ls1tech.com/forums/showthread.php?t=426348&page=2


John

[bink]

Per gameover on LS1Tech:

"the bits i change are just the P101,P102,P103 bits."




John

Could someone please explain this? Is he turning off DTCs or actually changing the pcm (0,1). This reminds me that I am - the analog man.


Cheers,
joel

[joecar]

I'm sorry I don't follow, please explain further...

The transmission line pressures are set by the values in {D0701} and the other tables under the “Trans Pressures”

John Oh, I see, you monitored the pid GM.TRQENG (calculated engine torque) and used the value of this to lookup D7001 and it said around 30/35 psi.

TOL (thinking out loud):
This means calulated engine torque is around 150/170 ftlb at idle...!!!
This points to the calculated airflow being wrong (i.e. VE table or some other table is off or way off...).
Just a thought.

[Ladyredhawk]

Oh, I see, you monitored the pid GM.TRQENG (calculated engine torque) and used the value of this to lookup D7001 and it said around 30/35 psi.

TOL (thinking out loud):
This means calulated engine torque is around 150/170 ftlb at idle...!!!
This points to the calculated airflow being wrong (i.e. VE table or some other table is off or way off...).
Just a thought.

If the MAF is unplugged/disabled for SD tune, the pcm cannot get an accurate calculated engine torque. So, in SD mode how does the pcm compensate for this and figure line pressure?

[joecar]

If the MAF is unplugged/disabled for SD tune, the pcm cannot get an accurate calculated engine torque. So, in SD mode how does the pcm compensate for this and figure line pressure? I'm not sure (...I never am any more... :muahaha:), but I suppose engine torque is calculated from calculated airflow (and other things), and then PCM uses calculated torque to lookup base line pressures, and I don't know if this applies at idle.

[Blacky]

I'm not sure (...I never am any more... :muahaha:), but I suppose engine torque is calculated from calculated airflow (and other things), and then PCM uses calculated torque to lookup base line pressures, and I don't know if this applies at idle.
IIRC calculated engine torque is looked up in a table that is not visible in EFILive. Maybe we need to make it visible so you can make the PCM's calculated torque value mimic "reality".

Paul

[GMPX]

A few nights ago I flashed in a SD tuning file using EFILive/AutoVE Tuning guide in my 98 Z28 with an A4 transmission and have a problem.

The PCM is commanding full transmission line pressure at all times. All shifts are very harsh. I checked the transmission DTC fault enablers for P0101, P0102, and P0103 and they are set to “No”
The Engine DTC MIL Enablers for these codes are set to “No MIL” per the EFILive/AutoVE Tuning guide.
What can I do to prevent the PCM from commanding full transmission line pressure on all but heavy/full throttle shifts?

Thanks

John

John,

Can you please send me your file?.
I'll make the change here for you to test with and if it fixes it we'll get some new 1998/1999/2000 cal files out with the fix available.

It's basically another enable/disable type table that looks to another pressure value if the DTC is set, in the 1998's the DTC's that will cause it to do that are TPS and MAF, in the 01 file I checked nothing will do it??. Thanks to all that let out some hints on what to look for, I always figured it was just the full line pressure faults causing it.

Cheers,
Ross

[jnorris]

John,

Can you please send me your file?.
I'll make the change here for you to test with and if it fixes it we'll get some new 1998/1999/2000 cal files out with the fix available.

It's basically another enable/disable type table that looks to another pressure value if the DTC is set, in the 1998's the DTC's that will cause it to do that are TPS and MAF, in the 01 file I checked nothing will do it??. Thanks to all that let out some hints on what to look for, I always figured it was just the full line pressure faults causing it.

Cheers,
Ross


WOW!

Thanks for looking into the transmission line pressure problem and finding a possible solution so quickly.
The file has been sent.


Thanks

John

[joecar]

IIRC calculated engine torque is looked up in a table that is not visible in EFILive. Maybe we need to make it visible so you can make the PCM's calculated torque value mimic "reality".

Paul
Thanks, that will help will A4 tuning. :cheers:

[jnorris]

John,

Can you please send me your file?.
I'll make the change here for you to test with and if it fixes it we'll get some new 1998/1999/2000 cal files out with the fix available.

It's basically another enable/disable type table that looks to another pressure value if the DTC is set, in the 1998's the DTC's that will cause it to do that are TPS and MAF, in the 01 file I checked nothing will do it??. Thanks to all that let out some hints on what to look for, I always figured it was just the full line pressure faults causing it.

Cheers,
Ross


I just tested the flash file with the changes that Ross posted about in the above post.

The changes Ross made in the file corrected the high trans pressure problem. My trans pressure now act the same with the SD flash as it does with the MAF flash.
Idle in gear - 0psi
Idle in reverse - 5psi
Quick stab (38% throttle) of the gas in gear - 90psi

Ross indicated that the new 1998/1999/2000 cal files with the fix should be available probably within the week.


John

[Black02SS]

I just tested the flash file with the changes that Ross posted about in the above post.

The changes Ross made in the file corrected the high trans pressure problem. My trans pressure now act the same with the SD flash as it does with the MAF flash.
Idle in gear - 0psi
Idle in reverse - 5psi
Quick stab (38% throttle) of the gas in gear - 90psi

Ross indicated that the new 1998/1999/2000 cal files with the fix should be available probably within the week.


John
Thats great news to hear! I did a 99 today but put a 01 OS in and didn't have a problem. I have heard very few 01's have this as well but I have never experienced it.

[Ladyredhawk]

I believe the problem I am having with the 01s is not DTC related. Whatever table it refers to when the MAF readings are unavailable (DYNAIR??) is off enough that it calculates the torque incorrectly and then therefore line pressure is not right. Or maybe Adaptive shift is off?? What ever it is, I don't have the problem when the MAF is functioning.

BTW, both cars have high stall converters and large cams with full bolt-ons. Other than that, all other drivability is fine.

[deezel]

I believe the problem I am having with the 01s is not DTC related. Whatever table it refers to when the MAF readings are unavailable (DYNAIR??) is off enough that it calculates the torque incorrectly and then therefore line pressure is not right. Or maybe Adaptive shift is off?? What ever it is, I don't have the problem when the MAF is functioning.

BTW, both cars have high stall converters and large cams with full bolt-ons. Other than that, all other drivability is fine.

I would guess one of two things...
1) You might have one of the (possibly) very few '01s with the same problem.
2) Your VE table is off in a few part throttle areas.

Have you re-mapped your VE table using autotune? I found a few places in mine that were off because I had been trying to use fuel trims (old school) to tune it.

[Blacky]

There are now two settings for DTCs that set the high trans pressure.
The top one sets full trans pressure, the bottom one modifies the trans presure by a preset constant. So it's not full pressure just higher pressure.

We should be releasing it in a day or two.

Regards
Paul

[Ladyredhawk]

I would guess one of two things...
1) You might have one of the (possibly) very few '01s with the same problem.
2) Your VE table is off in a few part throttle areas.

Have you re-mapped your VE table using autotune? I found a few places in mine that were off because I had been trying to use fuel trims (old school) to tune it.

VE tables are dialed in. Ltrirms all cells -2 to +2

[Ladyredhawk]

There are now two settings for DTCs that set the high trans pressure.
The top one sets full trans pressure, the bottom one modifies the trans presure by a preset constant. So it's not full pressure just higher pressure.

We should be releasing it in a day or two.

Regards
Paul

Great help!!! Thank-you!

[Black02SS]

There are now two settings for DTCs that set the high trans pressure.
The top one sets full trans pressure, the bottom one modifies the trans presure by a preset constant. So it's not full pressure just higher pressure.

We should be releasing it in a day or two.

Regards
Paul
Awsome!! This will help out a bunch.

[deezel]

These guys are great. Very responsive to customer needs. :rockon:

[Highlander]

Well.. my problem is the opposite.. my transmission is NOT commanding more pressure... it always stays at 90psi and my logs show most of the time TFMPRS PSI = 0.0 except on rare ocassions... this is with COS 3.