Although I need to look in more detail at the data for the 3 ‘judder’ runs (nothing particularly jumps out at me), I wondered if you noticed - i.e. could hear or feel - the engine speed cycling during the 10 seconds or so spent in 4th gear during the light throttle run?

Thank you so much for your replies guys.

In answer to if I could sense anything on the light throttle run, not that I recall. However, I have noticed the revs doing what I would call "hunting" at some stages.

In the 3 throttle runs I did feel anything wrong. On the judder runs, the judder was very apparent, as in my 80 year old mother would have noticed something wrong.

Thanks again for the help, really appreciate it

Very strange. Considering the judder is so apparent, you would really expect to be able to see it in your three ‘judder’ runs, but it just isn’t there. You generally see a 1Hz oscillation of around +/-100 rpm in engine speed (like we saw in Gsxr1250dave’s traces).

On the other hand, you can clearly see an engine speed oscillation in 4th gear during both the light and the medium throttle acceleration runs, yet it isn’t noticeable to the driver.





Phil

Hello guys, sorry again for delay in responding.

We drove the l322 over 500km at the weekend and I can report the following:

In 4th gear, the ossolating is noticeably there, you can hear it if listening and see it in the rev counter. It is not jarring in any way and I would say most wouldn't notice it unless pointed out.

Any ideas what this indicates?

Thanks again for reading and all the help.

The torque converter lock-up clutch is in its controlled slip mode in 4th gear during your light throttle run (to prevent the transmission of torsional vibration due to the low engine speed) and should be slipping at a constant rate of around 2-3%. However, clearly the slippage is far from constant and you can see the EDS6 current cycling to try to maintain constant slip i.e. the clutch locks so it backs off the current, then the clutch starts to slip excessively, and the controller re-applies the current. This would certainly indicate a mechanical issue with the torque converter.



I personally don’t agree with the addition of a friction modifier in the fluid to ‘cover up’ a mechanical issue (i.e. it won’t put friction material back on the friction plate) but, as discussed at the beginning of the thread, it is a useful temporary technique to prove that the TC LUC is at fault.



Phil

Thanks again Phil for your time and detailed reply.

Having read what you have said a few times, it make total sense to me now.

I have some shudder fix to hand so will add it and see what happens and report back.

If it does mask the issue, are we looking at a new TC? Perhaps the Gearbox itself is OK?

Thanks again

Quote:

If it does mask the issue, are we looking at a new TC? Perhaps the Gearbox itself is OK?