I'm really impressed Phil what you have produced from the CSV files You are clearly not only good in gearboxes
It gives really good insight of the TCC operation and I think it is in accordance with my experience that the TCC only engages when I lift the throttle. Is it correct to conclude from these runs that the TCC engages fully or can't this be read in these CSV files?

In these runs my right foot was indeed a bit heavy, although the rest of the traffic didn't notice that because the car is still slow with this engine Normally my wife says I drive like a blind old lady

And of course I'm really happy to record a few more runs at light throttle. At what percentage you suggest to do so? And to what end speed? I only can do this during the weekend, but will send them right away when I have them recorded.

Thanks for your help!!

The torque converter is fully locked because the engine & turbine speeds are identical. At this point, though, the throttle input is down to 30-40% because you’re backing off, so the TCC PWM solenoid doesn’t appear to be at maximum pressure.

Perhaps you could do a couple of runs, if you can find a quiet flat road, one at say 20% throttle and one at 30% and try to hold the accelerator as steady as possible. I appreciate it will take a while for the vehicle to get up to speed but we could then at least see if the LUC was engaging in 3rd and 4th gears too, as well as identifying if there’s a ‘controlled slip’ mode. With everything happening more slowly there are a lot more data points captured, which makes interpreting the results easier.

Phil

Thanks Phil for the explanation. Now need to find out why the TCC solenoid isn't at full pressure. Any ideas? Or need more information?

I will do the runs as you suggest tomorrow and get back to you with the CSV files.

I’ve had a look at the last four runs that you sent to me.

Your 20% throttle run shows that the LUC isn’t being activated at any point up to your ‘terminal velocity’ in 4th gear.



Similarly, on your first 30% throttle run, the LUC remains inactive.



However, your second & third 30% throttle runs are a bit more interesting.





The measurements are being captured at around 1.25Hz i.e. the data is refreshed every 0.8s or so. Unfortunately, on the last run (labelled bikeparadies) there’s a gap in the TC LUC data between 34.4s & 39.9s and then again between 48.7s & 59.0s where no data points are captured. Nevertheless, we can see that the LUC is being engaged in 4th gear at around 45km/h. It initially locks the TC solid (engine speed instantly drops by 300rpm) but then backs off to allow a small amount of slip (around 2-3%). Similarly, following the 4-5 upshift it locks the LUC momentarily but then backs off to allow a controlled amount of slip.

Clearly, it’s cold in Austria at the moment. I suspect that one of the differences between the three 30% throttle runs is caused by the transmission fluid temperature. The first one, where the LUC doesn’t engage, is at only 30⁰C whereas the second one is at 62⁰C and the third at 75⁰C. The torque converter is intentionally left open at low temperatures by the controller to allow the fluid to get up to working temperature more quickly. I’m not sure why the vehicle performance is so different between the Post (2) run and the other two 30% throttle runs, though. Was one uphill and the other two on the level, or something?

You would clearly have to produce a huge number of runs to determine the entire LUC map but, mechanically & hydraulically at least, it does seem to be functioning correctly.

Phil

Hi Phil
Thanks again for these insights!

Didn't know that the TC stays open in order to rapidly warm up the fluid. The Post (2) run was only 5 minutes from leaving home at -12 C hence the low fluid temperature. The road on this run seems very level but not 100% sure it is (might be some minor incline?). The other two runs at 30% are level.

Really glad with your conclusion that it looks normal in a mechanical & hydraulical way. Like you I still don't know why it behaves like this. Could it be that the TC solenoid is the cause?

Or do you think the accumulator spring configuration might be involved? I definitely have two springs which are out of the Sonnax configuration: The 2nd clutch spring has to be 60,452 mm, the in my valve body is 65, 45 mm and the Direct clutch accumulator spring should be 60,325 mm and it actually is 59,3 mm.

Joep

I don’t see any evidence of an issue with the TCC PWM solenoid. On the contrary, the LUC appears to be responding exactly the way you’d expect to the solenoid signal. I think if you want to see the LUC operating in 3rd, 4th & 5th gears you will need to get the fluid temperature up to ‘normal’ i.e. 90°C+

The function of the accumulators is to act only during gearshifts. I can’t see anything wrong with the shifts on the graphs.

I’m not sure what problem you are trying to solve here? Since you replaced the restrictive pattern filter with a proper IBS Filtran one, hasn’t the cold start issue gone away? What other problems are you having?

Phil

P.S. I wasn’t sure if this reference (on accumulator springs, etc.) was the same as the ones you’d already looked at :
https://www.transmissiondigest.com/identif...ve-bodies/

Hi Phil,

Thanks for sharing this with (and the forum members)!

The cold start problem has now really been solved, since the new IBS Filtran filter and fluid change. On several occasions (-9 till -15 C) it gave drive right after start. I'm really glad with it because I thought my gearbox and or TC was on it's way out again only after 6 years and 80000 km.

Along with the failing cold start I sometimes had a very short and slight increase in revs (50-100 rpm) around 70 kmh, mainly when fluid hasn't warmed up. I also had an increasing diesel comsumption which pointed me in the TC and TCC direction.

So fortunately I don't have a failing gearbox but have some indications which are worrying me: extra fuel consumption and revs slighty going up and directly falling back to the revs it was doing. The latter seems to me more that the box is seeking the optimum because it doesn't keep it doing all the time. Just once or twice and stays steady then. Am I correct in thinking so?

The upgoing fuel consumption could also be related to the injectors I guess. There are diffences between them in fuel compensation and in leak-ff test. So I should have them checked soon (and if necessary overhauled).
I am really happy with your conclusion that the TCC and transmission act as it should be so no worries to drive it I am going to keep a close eye on these revs and will sure try to log it and would like to ask you to have a look at it then. I will also try to log when the fluid gets above 90 C. I think this might be impossible these months (have every day minus temperatures during the day and really freezing during night). But will sure try to log as soon as I'm going to do a long trip. Is it okay to mail these files to you as sson as I think I have some interesting records?

Thank you Phil for the info on the accumulator springs and reassurence that the shifts look normally. So I think I can rule the valve body out. The link in your post is new to me and very interesting. I can cross-check it with the info I got from sonnax (I uploaded this some previous posts ago).

If you have any suggestions for me to pay attention to or to test, I'd be very pleased with your help!

Joep

Hi all. Sad news now; I got the Trans Failsafe Progr. message and car is only shifting up to 3rd now and stays there (no up- or down shifts).

Well what happened previous: During last month The shifting as previous described stayed the same, But it was mora and more clear that under load the TCC wasn't able to keep closed and opened almost immediately when going a little uphill or speeding up. Mainly at low temperatures (outside and gearbox fluid). This seemed to coincide with a simultanuously downshift to fourth gear. Furthermore at several moments the revs seemed to go about 200-300 Rpm before the TCC engages. I also experienced now and then a slight vibration/humming through the drivetrain

Then last week when I drove the car (started at -2 C) after about 2-3 KM i felt the vibration/humming a bit more pronounced at about 70 kmh. Then 2 KM later it was there again at 50 kmh. One KM later the road has a decline and is end of 50 kmh zone, so I accelerated with low torque and then the happened: very horrible sound from underneath (felt like TC was scraping against metal housing). I immediately lifted throttle, everything quit again and tried to accelerate smoothly. Same happened again and also the "boing" with the Trans Failsafe Prog message.

Gearbox was rebuild 7 years and 84.000 KM ago, with new TC.

Defintely something really wrong now. But where to start? Is it only the TC? Or should I have the whole gearbox rebuilt?

Any ideas mostly appreciated

Yes, been unfortunate. Opened up the pan and this was full of metallic debris. Something really got bang and it has to be the third gearbox rebuild (one for previous owner, two for me ).
Removed it now and it is waiting for transportation to the rebuilder.