Hi all,

I have a problem that's off and on. The car seems to jerk like when you down shift in a manuel transmission car when I slow down to come to a stop. Once the speed drops to about 10mph, I feel the car jerk like a downshift. The transmission shifts fine and smoothly other than that. There's no slip no grinding or anything. This happens off and on. Majority of the time it will come to a stop smoothly and sometimes it'll jerk. I assume if it's the transmission, it will remain. I've heard that it's possible to be the EGR, but I don't know anything about this. Does anyone know if this is true. Plus, if it is the EGR, what other symptoms would come along with it as I do currently have loss of power and hesitation during WOT along with fuel smell in the cabin after a couple of WOT punches. By the way, it is a 1998 XJR

Thanks much in advance

 

My guess is this is happening in Sport mode when engaging first coming to a stop. How bad is the jerk when it downshifts? I have a 2001 XJR that dose it either when it is cold or when the idle is too high; but it is not anything I worry about (correct the high idle though).

 

Is the CEL on? Any codes? EGR should throw a code like P0400.

 

Hi devxiav,

+1 on both Scott's and Mark's questions.

The first thing to do is to check the fluid level after a drive of at least 20 minutes. Park on a level surface and move the gear selector through all the gears, leaving it in each gear a few seconds so the gear fully engages. Return the lever to Park and check the fluid level and condition. The level should be exactly at the HOT line and the color should be bright transparent red. The fluid should not smell burned.

Assuming the fluid level and condition are good, if the transmission is in Sport mode, switch it to Normal and see if the problem persists. If it does, have the system scanned for any stored Diagnostic Trouble Codes (DTCs). I'm not sure if a standard OBDII scanner can read the transmission codes on an X308. It may take a system such as Jaguar IDS, WDS or SDD. Hopefully one of our other members can confirm.

An EGR valve that is stuck open can lead to high idle, as Scott implied, which can lead to rough shifting. An air intake leak can cause the same problem, but usually accompanied by a rough idle, which you don't mention.

Please keep us informed.

Cheers,

Don

 

Don, Is there a transmission dipstick on the XJR? How is it accessed? I didn't know I had one.

 

Thanks guys for the quick responses.

It does it on both normal and sports mode. The jerking is not to where would jerk you forward when sitting nor does it make and clunking sound. However, it's like downshifting to a low gear with a stick shift/manuel and trying to let off the clutch slowly balancing it. It idles fine and it does it both sometimes during when it's cold and sometimes during when it's hot (more when cold then hot however).

There were and are no codes so I guess that would elimate the EGR.

Don, I had tried shifting it into gears and letting it sit then going to the next and letting it sit as you've stated along with trying to manually shifting the gears while driving. Every gear was smooth. However, I haven't checked the fluid level nor have I checked the color because from what I've read on here I understand there is no transmission dipstick. Of course unless you can buy one if I am mistaking.

Again thanks guys for your help.

 

Hi,

This could be a symptom of a faulty "Shift Control Solenoid Valve". I assume you have no issues if you slow down gradually. Jerks while applying brakes is an initial symptom to start with and soon you will have problems while accelerating as well. If this symptom expands to shift speeds say, 40, 80, 120 km/hr in a month's time you should confirm this.

Hope this is useful.

Regards,
Srijit

 

Srijit, from gradually slowing down I assume you're talking about letting my foot off the gas and just let it drop in speed because you did mention if I experience this when applying the brake. If that is what you are referring to, I have not tried that. I will keep you guys posted

 

@devxiav...you need to identify if this initiates from a sudden change in the speed...normally initiates while applying brakes...so if it has just started you may be able to manage now...gradually it will start while slowing down...also try if problem persists while on sudden acceleration from 30 to 50 kmph or 50 to 70 kmph etc etc and rule out this possibility first...

 

The XJR has a Mercedes transmission and there is a dipstick tube but no dipstick. You can find one on ebay. It is not meant to be left in the tube, and in fact sticks out a long way.

Buy some caps for the tube at the same time. They are single use and break off to remove.

 

Oh right, cool, thanks.

PS, I saw the thread title, and thought it was going to be a rant about Prius drivers!

 

So it wasn't just me then. lol

 

Agree with Mark and AL; moreover, I don't jerk when I down shift a stick shift. I guess double clutching is a lost art . . .

 

Sorry guys. I forgot about that deficiency on your models. You have to check the fluid level and condition the hard way.

Cheers,

Don

 

Lol...that's funny.

An update. I guess the car is really that sensitive. It was a low battery. I took it in today to get it checked and it was quite low. The battery was recharged and the moment I put it on, it's smooth as new. Thanks guys for all your help.

 

@devxiav...It sounds strange that the car jerks due to low battery while slowing down. Is the update of a different car?

 

The question is, then, why is the battery low? Check the voltage at the battery, when the engine is running. Should be around 14V.

 

It's at 14V. Guess it's just an old battery. Haven't changed out in about 4 years or so.