So this is my first real issue since buying the car, and hoping people will weigh in to help me out.

2005 VDP 4.2L NA. 100,054 miles.

one morning, pulled the car out of the garage and it started to surge/lurch when put into gear. Drove a little further and found under acceleration it worked fine, but when conning to a stop it would lurch and surge hard again. No error lights or codes. Got it home and started doing research.

Came to the conclusion that at the mileage the trans fluid was probably shot. Decided to drain the pan and filled with Mercon SP as it is "equivalent" and I had plenty readily available. I followed the instructions from this forum very closely, but was slightly off on temps since it was 100*F in the garage. Felt good though about where everything fished up. Took it for a test drive and it drove great. Parked it in the garage.

The next morning I jump in and it is surging slightly and the trans fault and restricted performance lights come on. I hook up SDD, and go through diagnostics. Unfortunately I forgot to write down the code... but I followed the instructions and cleared the adaptations and reprogrammed the TCU. Everything went fine and the codes cleared. Took it for a test drive and it drove fine again... until you get to a stop. After you stop it will be fine and then do a little surge with a jump in rpm and then settle back down. Under acceleration there is no issue. No logged codes or lights. Drove about 50 miles and the only problem was after sitting at a stop light with the car in drive.

Since it did improve drastically with the fluid swap, my thoughts are that the original fluid and this Mercon are not meshing well and that I should do a complete drain and refill to clear out as much old fluid as possible, whether that be Liquid Gold or the Mercon.

looking got thoughts and ideas or feedback on my thought process! Thanks.

 

I'd 2nd the fluid. They're very fussy about using the correct type. I just had mine done and purchased what I was told was the correct alternative from Millers, a quality brand, my indie refused to use it......

 

I recently changed my transmission fluid of my X350, including the sump pan filter which takes up a lot of fluid, and it takes almost two hours to fully drain the system of old fluid. As for the replacement fluid, I took my mechanic's advice to use ZF Transmission fluid (6-HP) - it was meant to be used in all ZF transmission system.



It does take quite a while for you to feel the full effect of the new fluid, something like two weeks. I figured that this was because the old fluid had been with the car for the last 12 years, and the new fluid needs time to fully takeover and penetrate. Many Jaguar owners in Hong Kong were led to believe that Jaguar uses sealed transmission systems and hence the fluid can be used for life.

 

I've used Mercon SP for years with no issues whatsoever. Did you replace the mechatronic sleeve when you had the pan off? The seal may have gone bad and fluid may be leaking in and messing with the electronics.

 

I did not pull the pan. Just a drain and fill. My thoughts were to just try the fluid, since I could obtain the SP easily and quickly.

But a new update today, I am getting misfire codes on a couple of cylinders (happened once before, but went away). After some research this can show as a Transmission Fault so I ordered OEM plugs (NGK 7866) and AirTek (5C1240) coils and will just replace those. I figure mileage wise it is probably time, and I do not have the history on this car.

Whether the plug/coils fix it or not, I will order the pan and do a full drain of the trans as well.

 

If you are planning to replace the pan, be sure to also replace that mechatronic sleeve while you're in there.

A good test for coils is to swap it into a different cylinder and see if the misfire code follows it.

 

Definitely!

 

The conversion to a metal pan & filter, with Mercon SP has been one of best things i've done so far.

 

Bad plugs and coils can cause transmission confusion. I know from experience. My guess is that the transmission is using engine feedback and is not getting proper feedback. This engine does not easily give up misfire codes.

 

So an update in case anyone else experiences this. After using SDD to find out my codes of random misfire and excess emissions on 2 cylinders I replaced all plugs and coils. 5 of the 8 coils were original denso and the remaing three were unmarked, but the same design as the airtek ones I put in. Odds are I did not need to replace all coils, but figured the $ would be less than a tow in the long run. All my codes are gone, and the transmission is shifting beautifully now. Was super easy, even the "dreaded" #8 was fairly simple.

 

Did you remove the bulkhead for enough room to gain access?

 

NO, I didn't remove the windshield wipers, or the cover, or punch out the cover down by the master cylinder. I used different 3/8" extensions and a spark plug socket and everything came out just fine.

 

My issue was the coil seemed to be too long to come out without removing something,had it loose & in my hand. Guess i will look, & try again, the plug should be a non issue once the coil is out, as long as it's not seized. The universal socket with combinations of extensions usually is all you need to reach almost any spark plug.

 

It seems that way initially but it can be wiggled out. Don't be afraid of manhandling it a bit.