Feedback on trans pressure log

[ddnspider]

I wanted to get some input on a recent log that has some of the transmission parameters selected. I notice on upshifts and downshifts (especially) that it is a rather hard kick/shift. I don't know a ton about what was done to the transmission prior to me owning the car. The car is a 1998 Z28 A4, supposedly it is a basic 4L60E rebuild with some slight upgrades and may or may not have a shift kit. I read some of the trans tuning tutorials and especially with respect to the pressure section, it doesnt give me much information about what it should be under light/part throttle and then at WOT. Please take a look at the log and provide feedback. Should I decrease/increase pressure or increase torque reduction at part throttle on upshift/downshift until the kick goes away? 16163

[joecar]

Post tune file if you can.

[ddnspider]

See attached. Thanks Joe. 16164
Post tune file if you can.

[joecar]

You see harsh shifts at part throttle (kicks/jerks)...?

Do this:
1. check fluid level and color/condition.
2. add some torque reduction back into the 1->2 and 2->3 shifts (set it to say 25%) and see how it goes from there.

[ddnspider]

You see harsh shifts at part throttle (kicks/jerks)...?

Do this:
1. check fluid level and color/condition.
2. add some torque reduction back into the 1->2 and 2->3 shifts (set it to say 25%) and see how it goes from there.

I'll give it a shot and let you know. I checked the fluid level when I got the car and noticed the kick and the level was fine and the color was still nice and red. I'll check it again and add the torque reduction back and let you know.

On a separate note, any idea why the maf lb/min is so jagged? I logged another run with maf freq and it was jagged as well. Car runs great, and was done with calc.vet.

[EagleMark]

Should also get a stock .tun file and compare each parameter and see how much it has been messed with?

[joecar]

What MAF plumbing does the car have...? Is the MAF screened/descreened...?

[ddnspider]

I did verify that the trans pressures in the tune were stock. I only messed with shift points and torque reduction and shift time.

MAF is stock with screen and with a lid and FRA mod

[ddnspider]

Changed the 1-2 and 2-3 up and downshifts to 25% torque reduction from 0 to 250ftlb's. It seemed to clean up much of the kick on the upshifts, although there still is some kick on the downshifts. Attached the log just around town cruising.16192

[joecar]

TFMPRS [psi]:

at low throttle: TFMPRS is too low (practically zero)

at high throttle: TFMPRS jumps up ok (could go a little higher).

[joecar]

if you're having harsh shifts, try this:

- set shift torque reduction to 25%;
- set shift pressure tables to start rising from zero;

if you still see harsh shifts, then check if shift kit components have been installed.

Otherwise there may be a physical problem.

Can you measure line pressure from the tap on the driver side of the case (while driving/shifting)...?

[ddnspider]

I guess that's where my knowledge is lacking....what is TMFPRS supposed to look like at low throttle/load? I have not touched the shift pressure vs. torque tables. The stock tune calls for 0 psi on the shifts with less than 74ft lbs of torque and based on my logs it looks like its less than 10psi when torque is less than ~150ft lbs. Can you give me some background or an example on what the shift pressure tables should look like?

Setting torque reduction to 25% did help the upshifts, its just more noticible now on the 3-2 and 2-1 downshifts. As far as measuring line pressure I would have to figure out a way to run a gauge. Ive got some vacation coming up so I could play with it.

[joecar]

In-gear it is supposed to roughly follow TP and/or engine torque... your log show it falling to zero most of the time.

On each shift it follows the shift pressure tables... you log shows it doing this.

It's not so much what the pressure tables look like, but it is what TFMPRS is being commanded... yours is being commanded low, yet you still get harsh shifts.

Try setting some Torque Reducton on the downshifts also.

[ddnspider]

I added TR on downshifts and it seems like its better once the car has been running for a few minutes and, I assume, gets some heat going. As far as in gear pressure, what trans tables if any, are applicable to adjust? When I zoom in it looks like pressure rises with throttle and then falls off to zero so long as it doesnt have to shift. Since all of the upshift/downshift tables are commanding 0psi from 0-~75ft-lbs and the in-gear cruising is between 0-75 ft lbs, could that be why it is showing zero psi? Doesn't the transmission not require much, if any, pressure while in gear, but mainly for the shifts? Just trying to understand this correctly.

[joecar]

Unfortunately there are no visible in-gear pressure tables

(since I have not seen such tables using various other tuning softwares, I suspect that it might be a dynamic calculation based on calculated engine torque).

[joecar]

In each of the shift pressure tables do this:

eliminate the flat region by making the curve be an almost straight line from (0 ftlb, 0 psi) to (295 ftlb, 90 psi).


Then perform test drive, and edit the TR tables accordingly, see if you can get the shift feel to not be harsh.

Also, look at the temperature pressure adjust tables, these are the relative amount of adjustment at various temps, play with these also.


The trans does require some pressure in-gear based on engine load and torque... not as much as during a shift, but it still requires pressure proportional to engine output (which requires the engine's VE/MAF modelling to be good and not be significantly divergent).

[ddnspider]

Excellent. That was some of the info I was looking for. Can you take a quick peek at my MAF and VE table and see what you think? Its a bolt on 98 car. I tried to smooth where I could. I'll give the pressure changes a try tomorrow and post up. Thanks!

[joecar]

Excellent. That was some of the info I was looking for. Can you take a quick peek at my MAF and VE table and see what you think? Its a bolt on 98 car. I tried to smooth where I could. I'll give the pressure changes a try tomorrow and post up. Thanks!Ok, I'll take a closer look tonite when I'm on Windows (rather than Mac OS, lol).

[ddnspider]

Ok, I'll take a closer look tonite when I'm on Windows (rather than Mac OS, lol).A Mac??? Who owns a Mac? :angel_innocent::joke:

[ddnspider]

So I went and made the 1-2, 2-3, 3-4 pressure tables basically linear. It did seem to help with the kick on the downshifts. I am almost wondering if I should command something greater than zero at 0ftlbs because on decel, like when coming to a stop, I am basically in the 0-30ft lbs category. It did seem to help though.

Something else I noticed during the WOT partial 3rd gear, my commanded pressure was ~75-80psi, but my actually is ~60-63psi from 3700 rpms and up.....I looked at the high pressure adjust and it is set for ~8psi at 350ft lbs, maybe that is why the pressure spikes and drops off?? Open to other ideas.

PS...was the MAF/VE close? :)

16200

[joecar]

A Mac??? Who owns a Mac? :angel_innocent::joke:lol... it's a long story.

[joecar]

Try smoothing out the MAF curve by raising it immediately after those two [minor] kinks (i.e. and keep it rising smoothly with no kinks)...

i.e. try this:


LABELS MAF Sensor Calibration (Grams/Second)
Hz {link: GM.MAFFREQ} Value
1500 4.098882
1625 4.209634
1750 4.429455
1875 4.755161
2000 5.182403
2125 5.706114
2250 6.321008
2375 7.022082
2500 7.805053
2625 8.666721
2750 9.605203
2875 10.620051
3000 11.712233
3125 12.883995
3250 14.138620
3375 15.480113
3500 16.912850
3625 18.441246
3750 20.069484
3875 21.801349
4000 23.640179
4125 25.588949
4250 27.650435
4375 29.827420
4500 32.122871
4625 34.540041
4750 37.082455
4875 39.753819
5000 42.557886
5125 45.498409
5250 48.579231
5375 51.804600
5500 55.179638
5625 58.710872
5750 62.406608
5875 66.276931
6000 70.333181
6125 74.586852
6250 79.048058
6375 83.723837
6500 88.616680
6625 93.723649
6750 99.036362
6875 104.541915
7000 110.224630
7125 116.068316
7250 122.058629
7375 128.185111
7500 134.442570
7625 140.831656
7750 147.358633
7875 154.034594
8000 160.874419
8125 167.895865
8250 175.119046
8375 182.566445
8500 190.263371
8625 198.238568
8750 206.524591
8875 215.157513
9000 224.175669
9125 233.617347
9250 243.517601
9375 253.904603
9500 264.796109
9625 276.196622
9750 288.095770
9875 300.468183
10000 313.274940
10125 326.466383
10250 339.985901
10375 353.774115
10500 367.772845
10625 381.928268
10750 396.192802
10875 410.525447
11000 424.890625
11125 424.890625
11250 424.890625


Try that, but keep an eye on trims or BEN.

[joecar]

Try the attached file (I adjusted pressure/time tables, and I also made a few tweaks to VE table).

[ddnspider]

Joe,

Got your tune loaded and went for a drive. Here's the log. It feels like it fixed the "kicking" issue. I'm not sure which was the main fix in the tune that solved this issue. I'm also not sure what to make of the trans pressure at WOT either. It looks like it stays in the 60's and then jumps to 80 psi for a given rpm range. I didn't log fuel trims, and the MAF lb/min is still jagged, but the car did feel like it pulled smoother.

16210

[joecar]

The fix is a combination of tables (increasing shift pressure and offsetting it with some torque reduction)...

I'll take a closer look at your log later tonite early tomorrow.

[ddnspider]

The fix is a combination of tables (increasing shift pressure and offsetting it with some torque reduction)...

I'll take a closer look at your log later tonite early tomorrow.

Thanks! When you get a moment, I'd like to better understand the Abuse mode stuff and how turning it on helped. I'm also wondering if the upshift torque reduction can be reduced in the ft/lb area at WOT, so i still have it at 25% in the part throttle power region, but then decrease it for WOT shifts. Good stuff Joe! At least I'll know this stuff for the next A4 car I have to tune.

[ddnspider]

Looks like the fueling is a bit rich now based on trims, I'll try pulling the same % across the board so it still keeps it nice and smooth. Also, I took a look and the trans fluid is still nice and red, the level may be slightly high, but it looked good.

[joecar]

Thanks! When you get a moment, I'd like to better understand the Abuse mode stuff and how turning it on helped. I'm also wondering if the upshift torque reduction can be reduced in the ft/lb area at WOT, so i still have it at 25% in the part throttle power region, but then decrease it for WOT shifts. Good stuff Joe! At least I'll know this stuff for the next A4 car I have to tune.Abuse mode is simply when you shift into gear when rpm and/or throttle are too high, it just protects your driveline and motor mounts just in case.


You can try reducing the TR at WOT, test drive it and re-adjust if necessary.

[joecar]

Looks like the fueling is a bit rich now based on trims, I'll try pulling the same % across the board so it still keeps it nice and smooth. Also, I took a look and the trans fluid is still nice and red, the level may be slightly high, but it looked good.I usually run the ATF level about 1 pint high.