2005 XJ8L

Hello everyone!

Since this is my first post let me start with thanks to all that make this forum possible: Thank you very much!

I need advice with a minor (yet) issue I noticed on my (new to me) 2005 XJ8.

In 3rd and 4th gear I noticed a slight RPM fluctuation if I keep the acceleration at/around 1500.

Does not happen unless those conditions are met. What can it be and where should I start looking at?

Many thanks!

 

Welcomm to forum!
Gourgeous JAG!
You can find many posts here on subject of slight, about 200rpm fluctuation at various conditions.
IMHO what you discribing is transmission hesitating because you have very light torque from engine (constant RPM). Try same thing only going UP HILL!
Read up on the subject here on forum. You most likely find here somebody else describing similar behavior.

 

The fluctuation is not even 100 RPM. Tranny?

I looked up what the system recommended on the subject and found 2 possibilities: engine oil out of spec or tranny in need of an oil change.
I’ll try the uphill in a few minutes. BRB.

 

I had a similar symptom on my car, fluctuating RPM at a constant speed. It was cured with a transmission oil and filter change.

Best regards,

Thomas

 

Thank you Thomas! I did the engine so I’ll do the tranny as you recommended.

 

Did the UP HILL! Still fluctuating RPM. I’ll change the tranny fluid. We’ll see.

 

If you're new to Jaguar, read up on changing oil in transmission! There is no deepstick!
You need to have car LEVELED and temperature needs to be within specified parameters! This transmission is sensitive to both under and over fill.
If you decide to change fluid, you may want to do some preventive service as well, while you there:
https://www.jaguarforums.com/forum/x...-fluid-271804/
How many miles on the clock?

 

200k

 

Hello... I had a 2004 XJ that surged when I first bought it... It was driving me crazy and (if I remember correctly) there was a TSB on this issue requiring a reflash of the TCM (again if I remember correctly)....but members in this group suggested I try BG 44K fuel treatment. Use two cans. Fill up the car (pour in the 1st can), run down the tank of gas, fill up the tank again (no treatment) and run it down.. Then fill up and pour in the 2nd can of BG 44K contents and run it down.

it worked! My XJ ran as smooth as silk. No more surging. The cans are quite expensive though (approx $25/can).

Just my 2 cents.

Thanks

 

Love the Jag in zircon

Blue zircon
Zircon is available in a rainbow of colors. Reddish-brown earth tones are common, but bright red or green gemstones have higher market value. Blue zircon is the most popular variety. It comprises 80 percent of all zircon sales and commands the highest prices.

 

Thank you! I found the product at $45 for 2 so I jumped on it. We’ll give it a try! Thanks for the tip!

 

Zircon is a favorite color for sure!! Just beautiful.
Attached is a ZF transmission TSB for this symptom. Note it's for the S-Type but you XJ has the same transmission.
So might be worth a look?

Here is a good list of Jaguar TSB's too.
TSB Listing
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It might help as an additional measure, but I would still do the transmission oil change. With 200k on the clock it is definitely worth to do it, also to extend the lifetime of the transmission.
By the way, an oil change of the diff does not hurt, as well, and can be done at the same time as the transmission oil change.
Best regards,
Thomas

 

You’re right! Tranny and diff same time makes perfect sense.

 

bad converter

 

Sorry, can you be a bit more descriptive? You mean catalytic converter? They are both new.

 

No the TQ in the transmission. You have a TQ clutch that's failing causing it to lock and unlock which then causes the slight RPM fluctuation. There is a TSB out on it and I was going to post it but I can't find it right now.

I think this is it but note it is for the S-Type but your car has the exact same transmission so I think it will apply?
This repair is software related so no parts changing. It might be an easier first step before changing anything?

I also attached another TSB which might help too? I don't see where you have this code either so might be worth doing some scans first?
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