Resetting Idle Adaptations on AJ16 engines

XJ-S
1

Wanted to let the forum know that I have a working WDS and I believe I can confirm that it can indeed reset the fuel trim adaptations. I haven’t tried it…well, because I’ve finally chased down all the issues that caused the trims to get up to the +7-10 range. It is now down below +3.

I’ll probably give it a shot for the hell of it though. I’ve attached a photo of the glorious screen that gives me access to a part I always thought only a PDU could do!

I also want to share, and correct a rumor that the Genrad GDS500, and probably GDS510, can also reset these adaptations…it cannot. I have access to the GDS500e, and it’s basically a big code reader that can pull Jaguar specific codes. It may be more useful for newer models, but it has very limited abilities for the XJS.

All in all, it’s a convenient size to pull ABS codes and the like.

Genrad Screen.JPG2448×3264 2.55 MB

2

That’s very cool. Any indication that the WDS is compatible with the 6.0L V12? We discussed this not too long ago and at the time, the consensus was that the WDS should be useful only to the MY 95+ 6-banger owners…

Steve

3

I don’t believe there is a cable that will connect your 6.0L v12 to this machine. Unfortunately I think this only works for the AJ16 engine, not even the AJ6.

4

Thanks. Now we have a confirmation.

May I ask if you know what happens with the adaptations on the AJ16 when you disconnect the battery? Does the ECU store these values permanently, or battery disconnect resets everything to factory defaults?

Steve

5

Stores permanently. I know for a fact that trims for the AJ16 engines are not affected by loss of power. Disconnecting the battery or touching the negative with the positive serves no purpose.

6

Thanks. We (I) need to confirm then whether the 36CU for the 6.0L V12 does or does NOT loose the adaptive trim.
If it doesn’t, I will have to drive to Virginia to pay your buddies with the PDU a visit before I rip off the engine harness and look for a needle in the haystack.

Does anyone know?
Steve

7

When we were issued the WDS at the Jag dealer in 1998, we were promised that the earlier cars from about 1990 onward would get the software incorporated at some later date… It NEVER HAPPENED!!!

We got the cables for XJ-S and XJ40 etc. but they don’t do any good without the software.

We still had to use PDU for the earlier cars.

bob

8

By the way, certainly not my buddies.

I would use the Rockville shop before I used the Springfield shop. They were much more responsive.

If I were in your shoes, I suppose I would go to the shop with the PDU and roll the dice.

9

Hi Bob:
You know these cars. Does the 36CU reset completely after the battery is disconnected or not?
I know that all DTC are purged from the memory but the BIG question is what happens to the adaptive fuel trim, do you know?
Steve

10

I was being sarcastic, I know what your opinion on that shop is.
BTW, if it comes to it, I will have no choice – PDU or bust.
Steve