Hello, just got a 1998 XJR and I am coming from a X300 xj6 so it looks like a blast driving this car.
Anyway the engine stumble sometimes when I am stop at traffic light or parking the car and when it happens if I am not careful with the throttle it easily comes to a stop, the engine goes off. It does not happen when driving on the street on freeway though, at least for now.
What it could be ? the mechanic is trying to look at it since he sold the car to me, but he has not a clear idea of what it could be.
The car has 220000mi but engine was replaced and current engine has 60000mi, transmission has been just rebuilt.
Any hints on how to troubleshoot it ?
thanks a lot

 

Welcome to the dark side xjfourty....lol....have you seen these TSB's.... http://www.jagrepair.com/images/TSB/...20Throttle.pdf ....and... http://www.jagrepair.com/images/TSB/...Flowcharts.pdf
For the source of those you'll want to bookmark this if you don't already have it.... JagRepair.com - Jaguar Repair Information Resource
For other TSB's, prompt the link in my sig....
You may simply need to adjust the cable or TPS....can you tell us a bit more detail? Does it stall like the engine is simply idling down below idle speed or is it a sudden shut off like if you have it in gear and it cuts out? You haven't mentioned any codes or restricted performance, ...none of that?
I would very suspect of and take a look at the MAF also....by removing the connection (before starting), your ECU will go into default when started and send a code. This will put your fuel trims in a balanced drivable default. Your hard acceleration will be hampered, but you should be able to drive it without stalling. You'll need to reset that after reconnection, but you'll have determined if the MAF may be your culprit.

 

Hello the symptom is like the engine is simply idling down below idle speed. but this does not happen always.
I Am not sure about restricted performance. I never drove an XJR V8 before and to me it looks like a missile. but I may be biased because I am used to drive a 1996 XJ6.
Thanks for your input really.

 

Maybe the throttle body butterfly just needs to be cleaned.

 

hmm seems like not easy job to do myself

 

Very easy. Take the intake tube off, hold the butterfly open and clean it and the throttle body with solvent on a rag. Wrap the rag on a small stick but do not spray solvent in there. You can buy throttle body cleaner in a spray can but it's not necessary, even gasoline works.

 

But while you clean the throttle bore and plate, also clean the MAF sensor and maybe run some fuel system cleaner through a tank of gas. Make sure the tubing from the air cleaner box to the throttle body is air/vacuum tight. Be sure you have new high test gas. Maybe a new fuel filter; how does the air cleaner look? Next step would be plugs. Then, check what repair orders were left in the glove compartment: determining if you have newer timing chain secondary tensioners is critical.

When I bought my last X308, in 2013, I walked through these steps: ran like a new car for very little effort or money.

 

Don't be intimidated by this lady, she'll talk to you. Folks like Jim, RJ and myself will try to be as helpful as possible in your endeavor. What would you consider your mechanical skill level to be on a scale of 1-5? Is the PO (previous owner) mechanic assisting and your passing on the info? For yourself, a very easy to use OBD II Bluetooth device is the Elm327 (very affordable also from Amazon). Use the phone app "Torque" (Pro version preferably) and you'll be able to monitor items like thrown codes (and clear them), fuel trim, temperatures, RPM and such info that you can forward here for diagnosis.

 

after driving it for 3 days the stumbling behavior went away.I know the car has been sitting for long time. The engine is a 60000mi engine just installed 1 week ago along with a rebuilt transmission. So maybe it just needed to be driven more. Now I have to make sure the tensioners problem is addressed

 

The stumbling may be related to your video in https://www.jaguarforums.com/forum/x...98-xjr-206637/

 

the stumbling problem showed up again. I can say it happens between 1000 and 2000 rpm, most likely between 1000 an 1500.
The engine does not stall anymore because I try to keep it alive with some throttle action anyway between 1000 ans 1500 rpm you can see the the
rpm meter going up and down something like if the computer it's trying to keep things working but it cannot and at the end the engine is stalling.
I wanted to clean up the MAF sensor but I do not understand how to remove it from the pipe where it is installed into. Also if I Want to completely replace it which one should I buy ?
I read the codes and I found no error codes so far. I Also used and ELM device and didn't see anything bad.
thank you

 

To clean it, it's just a matter of 2 screws on the top of the unit, and it pulls straight up out of the tube. Clean it, let it air dry, replace, and that's all there is to it. It'll also have a part number on it which should give a good indication of the replacement to look for.

 

thank you. Any particular cleaner product that should I use ?

 

Surprisingly, it's MAFS cleaner. Don't use any other product and don't try to scrub it.

 

Only MAF sensor cleaner, available at any parts store. (you beat me RJ when I looked up my old order...lol)
If that doesn't work for you and you need to replace it, this is where I got mine 4 yrs ago....

 

I would not want to be wrong but looks like that the OEM part (DENSO) comes already inserted in a pipe and mine looks the same as this picture and I could not find any screw to remove the MAF sensor from the pipe. This replacement part is $200 on rock auto... pretty much expensive...

 

Yes so I would first try to clean it given that it's so expensive... thanks a lot for the hints.

 

I'm disappointed about m mechanic. He sold me the car and now he does not want to know anything anymore. He stated that the rattling noise I hear is nothing and that it is normal because it is the supercharger noise. Well turns out it does not come from the supercharger... I am not a mechanic but my hears can hear very well were a noise is coming from. So I'm trying to debug and fix things myself when I can. I can't fix the tensioners problem, but have a bunch of other things to take care of on this car.

 

I think your making the tensioner repair sound more complicated than it is (but its your option, its your car after all)...especially if its just the uppers. Prompt the link in my sig after "How to Fix" and look for the link by Blackonyx. It explains in detail the complete break down to replace tensioners, guides and chains. If you find out you only need to do the uppers (2nd-aries), then you at least know your issue. All just simply removing the cam covers and looking.
Along with the full out repair by Blackonyx, here's one on just the 2nd-aries from JagRepair.com - Jaguar Repair Information Resource.... http://www.jagrepair.com/images/Auto...eplacement.pdf

 

I never replaced tensioners and chain in my life...
I am completely a newbie about it. May I kindly ask to have a list of replacement parts that I need to buy to do the job ?

the mechanic asked me $2800 for replacing all tensioners and chain...
I will look at your post and see if I can make it...
thanks a lot