My 5.0 S/C has started juddering. It seems to have all the symptoms of the TC clutch but I'd like to be sure before deciding what to do next.

I logged some data from the IIDTool and plotted it in excel (click picture for a larger version or the full excel log is linked at the bottom). Around the 175 and 340 time points you can see the engine rpm and turbine rpm start fluctuating up and down. I've also took a picture of the adaption values (I'm not sure they are any use from reading other threads).

Any help would be appreciated.

Click image to enlarge

Unfortunately, during the important bit, the resolution on the engine speed measurement is only around 1Hz, whereas for the turbine speed it’s around 6Hz. This makes it difficult to decide, just looking at the graph, whether the engine ‘judder’ is real or not.



I wondered if it might be possible to capture the vibration again while recording engine speed, turbine speed and the EDS2 solenoid current, not bothering with the vehicle speed for now to hopefully improve the data capture rate?

As you mentioned, the charge pressure adaptions indicated by the IIDTool for the 6HP28 appear to be complete gibberish. For example, 421kPa is a 4.21 bar ‘adjustment’ to a solenoid which operates off a modulated (constant) 5 bar supply.

Phil

Jack, what were the symptoms of your judder?

I’ve got what feels like a hesitation on my car that I initially thought was engine related but I can’t find anything wrong with that so I’m not wondering if it could be transmission related.

Mine seems to occur between 1500 and 2000rpm, it’s worse when warm and shows itself at its worst when climbing a hill on the lane up to the house in 2nd or 3rd gear.

On the motorway with the cruise control set to 65-70mph you can see the revs fluctuating on the dashboard. However, when sitting at a steady 85-90 the revs are solid and there’s no hesitation from the car.

You can accelerate through the hesitation by taking the revs up over 2000rpm or by flooring the car and letting it take off like a scalded cat.

The gearbox is very smooth at changing gear, and had a fluid change done on it within the last 20k miles.

Here’s a screen record of the values from the IID tool whilst sitting on cruise control at 55mph (I think it was 55). You can see the turbine speeds and transmission output speed are both rock solid but the engine RPM’s are fluctuating quite a bit.

https://youtube.com/shorts/GVecayPbJO8?si=yz-3w4ZEvshFJVA-

Any help or suggestions would be greatly welcomed as I’m starting to struggle with diagnosing this now.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior