JNorris

iTrader: (4)

A few nights ago using FlashScan I flashed in a SD tune in my 98 Z28 with an A4 transmission. I used the process documented in the EFILive/AutoVE Tuning guide.

All seems to be working well except 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

chrisj6

Did you actually unplug the MAF?

Chris

JNorris

iTrader: (4)

Yes the MAF was unplugged.

chrisj6

That would be why, plug the MAF back and set the MAF fail freq to 0, this will set the car into SD mode. Also, if you wanna turn off the SES light, you can just uncheck the SES enable for the 3 MAF codes, but do NOT set the codes to "no error reported."

Chris

JNorris

iTrader: (4)

Thanks for the info.

Below is what I did with the codes.

12. Open calibration {C6002} " Engine DTC MIL Enablers" Set P0101, P0102, and P0103 to No MIL.
13. Open calibration {C2901} “MAF High Frequency Fail 1" Set it to 1 Hz.
14. Open calibration {C2902} “MAF High Frequency Fail 2" Set it to 1 Hz. If calibration {C2902} is not available in the operating system that you are using, then ignore this step.
15. Open calibration {C2903} “MAF High Frequency Fail Limit" Set it to 1.
16. Pop the hood and unplug the MAF sensor.

Is there a way that I can unplug and totally remove the MAF without commanding the high line pressure?

John

Brains

iTrader: (7)

Send me your file and I'll take a look for ya

MeentSS02

iTrader: (11)

If you can't figure out a way to remove it without commanding high line pressure (although I'm sure there's a way to do it), just leave it plugged in, set the fail freq. low (as you have done), and also zero out the MAF table completely. It'll fall into SD mode immediately...this would at least let you continue tuning for now while the A4 brains on this site help ya!

2000Firehawk

iTrader: (248)

Running SD on an A4..what controls line pressure..

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Thought the MAF needed to be there for the computer to figure out what amount of load there is so it can figure line pressure...
but If you want to run SD with an A4 does it revert to 100% line Presure???
or does it use something else to calculate load??
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VE table is used to calculate airflow, that then feeds into the torque calcs etc.

In some early calibrations 97, 98 and early 99 the MAF DTC would trigger the trans to shift at full line pressure, however this was calibrated out by GM mid '99.
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so what do you do on a 98 A4 that wants to run SD ??

unplug the MAF and see what happens. If you get hard shifting, email me the file and i will fix it for you.


Found the above on the HPTuner web forum.
A 'bit' has to be turned , on or off, I think, for the very early PCMs.
If you have HPTuner, email Chris your OS number, & he will tell you if you need the 'fix'.

aux_fast_cam

i've played with line pressure some it can and will damage the 1/2 plastic piston servo if you are not careful--on aftermarket A4's there aluminum

Lady Redhawk

iTrader: (6)

I posted a while ago about this same thing happening to my 2001 A4. I looked at it with EFI Flash/Scan as well as LS1edit and HPtuner. ( I have all three programs ) Every thing was turned off from the factory that would command full line pressure because of MAF for my 2001, but some how it was still going there. If I just set the MAF fail tables to 0 and plugged the MAF back in, it seemed to fix it. I had no codes that was saying it was at full line pressure, it was just hard shift at normal driving conditions.

Blacker

iTrader: (3)

Mine was doing the same thing when I removed the MAF. I sent my bin file to HP Tuners and they fixed it. I still have my MAF removed and transmission shifts are just fine.

Lady Redhawk

iTrader: (6)

What did they change to fix it?

DrX

iTrader: (6)

Are you referring to table E0102-Trans DTC Max Pressure Enablers(if you have it in your OS) when you say all airflow related DTCs set to "NO" including P0101, P0102, P0103?

The only stored DTC you should see is P0102. Are there any others set?

I was having more problems with SD tuning when I left the MAF plugged in. It is unplugged now.

I assume that the Trans Pressure tables(starts at D0701) are not maxed out in your tune?

joecar

I also am curious.

JNorris

iTrader: (4)

Yes I was referring to table E0102-Trans DTC Max Pressure Enablers.

I did not check for DTCs.

All my Trans Pressure tables are set at stock values.


John

2000Firehawk

iTrader: (248)

What did they change to fix it?

I think that they change something in the OS.

It's something that we can't change with our HPTuner program....

joecar

And the answer is...???

Runn

Ttt...

Black LS1 T/A

Sombody don't wanna talk ... maybe Bush can put a wire-tap on their azz

Lady Redhawk

iTrader: (6)