This may have been covered in a thread somewhere so forgive me. If it is, I have not found it after searching related keywords so, if someone knows a link, it would be appreciated. I have found many threads covering the same issue but non that give a good description on how to get the bugger out.

Anyway, I recently bought a 1996 XJR and it has the high idle condition. After checking the obvious like cables and what not I have concluded that the TB is gummed up. This was confirmed by running a bore scope down the intake and seeing the gunk build up. I usually end up taking apart way more than I have to when in uncharted territory so if anyone can help with a "how to" of sorts I would greatly appreciate it.

Thanks in advance

 

https://www.jaguarforums.com/forum/x...g-cured-97026/

About half down is a procedure. Can anyone confirm if this is all there is to it? For as many threads as I have found on the issue, this would make a great addition to the "How To" section if it is accurate.

 

Hello
I am affraid that I have bad news for you. what you need to do, is a son of a bitch, and there is no easy way, they are all hard. Probably the easyest way is jack up car, pull the oil filter, and the suport rod for the intercooler, then pull the big hose that goes from the intake plenum under the intercooler to the throttle body, it has a aluminum tube inside it. This sounds easy but trust me it is not, there is lots of stuff in the way. Then at least you have access to the throttle body and you can clean it out with out pulling a bunch more stuff.
Good luck. The XJR is a really cool car, but it is so much harder to work on anything on the intake side than the regular XJ6

Best wishes
Darryl

 

Darryl, Thanks for the response. I'm beginning to get a sense of why the guy I got the car from didn't want to be bothered and why he gave me such a good deal on the car. Between the sticky TB and the replacement seats he put in it not being compatible wiring thus, not being able to adjust them, those are the only things hindering being able to drive the car down the road. I just have to dive in and get it done. Can't wait drive it!

 

I have worked on a lot of vehicles in the last 25 years including several top to bottom restorations but, taking the throttle body off of an AJ16 qualifies as one of the most difficult things I've ever attempted. I got the front bolt out of the aluminum air duct that goes down the back side of the intercooler but couldn't get enough torque with my flexible extension to get the bolt on the side towards the motor down underneath. I ended up using a hacksaw blade between the air duct the back of the intercooler and cut the bolt. I will come up with some other type of fastener to replace it with.

Anyway the back air duct is off and the flex hose that connects that to the throttle body is off. With that I decided to call it a night. I'll get this throttle body clean eventually

 

I bet you thought I was kidding about it being a son of a bitch. Like you I restore and fabricate cars for a living. but that job is a bugger.
Just wait until you have to replace the lower radiator hose ( the dreaded octopus hose ) it has 7 count them 7 different connections and almost all of them are a bugger to get to. I cannot begin to tell you all of the stuff you have to pull off to replace the hose. I wound up pulling the supercharger with the throttle body attached just to get to it.
Buyer beware of the XJR that needs work, it is a really cool car but I am not sure it is worth all the drama. I have had Jags for 30+ years and lots of X300s ( I think I am on #7 ) and they are great cars, very reliable I have a 96 VDP with 230,000 miles and an old 72 series 1 with 477,000 that I have had for 30 years. But that XJR has been a problem. I currently have the diff out of it due to noise and found the spider gears were worn pretty bad. And good luck trying to find them new. So I am trying to install a new after market LS unit ( Auburn ) fingers crossed we can make it work.
So good luck
Darryl

 

For me the only way is from the top and remove everything so it can be cleaned also a good time to change that octopus hose

 

Octopus hose is now at least visable

 

Easiest way to clean the throttle body is to do what i did. Forget to remove the rag you stuffed in the air box when you take off the top half to renew the gasket. Start the car and suck it through to the butterfly valve. Then use a coat hanger hook contraption with a mirror to pull it out.

Hey while were discussing the intake side can someone direct me to more detail about the egr carbon blockage and the bypass valve. I am getting an egr code and Id like to chk that bypass valve for any possible performance loss. But I dont want my intake system to look like the white car in the above photo while im doing this.

 

It all went back together with out to much trouble




Fitted a catch can to help keep the TB system clean

 

Did you look inside the head to see if the valves and stems were covered in oil as well, and if so clean them while the intake was off?

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Well, my TB has begun to stick really badly, especially in colder weather. It's been sticking occasionally for a couple years, but it's gotten scary in the last few months.

Soooo, I've got to pull the TB and clean it.

I tried to get to it from the side by removing the intake tract, but unsurprisingly that was impossible. I tried to also approach it from the bottom, but for various reasons not the least of which was the lack of a lift and the band clamp nuts were turned so you couldn't get to them from under.... that too wasn't going to work out.

So I'll be following Moff1959's lead and remove everything from the top, which really isn't that bad as the entire tract is literally dripping with 20 years of oil vapor, so it's a good opportunity to clean it all out.

An interesting aside: I purchased one of the Jaguar TSB 03.1-15 oil separator a while back, and had planned to install that to address the oil in the intake track, only to realize it is for the NA(normally aspirated) cars only. I think one might make it fit the SC(super charged) cars with some fiddling although it would be tight to find a location, but it clearly isn't made to fit and the TSB even says it is for NA cars. So I'll probably just fit an aftermarket catch can.

I also will probably install my Maxbore TB at the time while I'm at it....

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Anyone know the torque values for the four bolts that mount the XJR throttle body to the "throttle adapter assembly (bypass valve body)" that sits between the throttle body and supercharger?

Trying to get the TB and surrounding equipment all put back together this week, but this one specification is holding me up as mounting the TB is the first step.

There was some brief discussion in the thread below, but conflicting specifications are given:

https://www.jaguarforums.com/forum/x...ue-spec-57979/

I'm thinking the torque is the "Bypass valve to throttle body 8.5 to 11.5Nm" in the service manual.


The X308 throttle body removal and installation guide specifies 18-24Nm. Not the same part of course, but maybe a clue?

https://www.jaguarforums.com/forum/a...e-body-r-i.pdf


I checked my copy of JTIS, and while it does have instructions for the entire supercharger removal and installation, it doesn't have steps for the throttle body and my copy of JTIS doesn't have any torque tables.

.

 

Have to agree Al, the catch can is on of the best mods I made on my 95 Norm Asp. It's even more valuable on a supercharged or turbo engine

 

Apologies to keep bumping this question, but need to try to confirm this torque value before this weekend so I can get the car back together.

.

 

Well, this photo looks familiar.... and now that I've got it all back together, let me confirm what a major PITA this was

It's not that the system is particularly complex, or even has a lot of parts to remove, but it is that everything is sooo jammed in a small space, there is no clear service manual or DIY step-by-step, details like torque values are unclear, and even if there were I don't think based upon my experience there really is any sure-fire reassembly technique that will avoid some final Rubik's cube assembly dependency that makes it quite tough. So apologies if I too didn't put together a DIY, but again I don't think there is any "trick" I've really run across other than disassemble methodically, take lots of notes/photos, and take your time. There are a lot of plastic bits, wiring, bolts and other parts that don't have a lot of give or capacity for error such as pressure, twisting, pulling, etc... and if you break them, you'll be sorry. Also, buy everything including tools you think you'll need in advance such as spare bolts, gaskets and specialty wrenches.

Now, I think it will be easier next time as with all endeavors, and it probably won't be as stressful or risky. But there are some issues like the octopus of wiring that threads THROUGH (what a moronic design, at least have a connector to break it in half!) the intake runners that makes removal and reinstall quite difficult as there is nigh any slack once the 7 connectors are reattached, and then there's the "flexible" (not, it has an aluminum tube inside) 3" wire spiral reinforced heavy rubber accordion hose that connects the TB and the intake elbow that is longer than the gap between, and you have to pry on with one hand blindly from under the car.... fun fun. One lesson learned on the hose if there is a next time is to see if I can connect it fully before the intercooler/intake combo is fully bolted on, but that may be a pipe dream as I only have so many hands.

Well, anyway, it's all back together and does start, idle fine and get up to temp so far. So I'll tentatively say success. Now I'll need to drive the car around town for a few days before my confidence is high that I didn't break or mis-assemble anything like creating coolant leaks.

But I did clean out a TON of oil. I put a few gallons of acetone through the intercooler after cleaning with degreaser, and it still ran tea colored after several cycles. I replaced the temp sensor under the intercooler as well since it was caked with oil... and the entire intake tract and TB itself, unbelievable. The only thing I didn't remove and completely clean was the SC itself. But from the standpoint of what I did clean, it surely will run better as it had to have been plugged up like someone with a head cold.

Keep your fingers crossed for me that it all went back together fine, and no unintended consequences come up. It's a bit unnerving and stressful having that much stuff off, no "instructions" and having to fight every inch to get it back together. I will probably lose my mind if I have a significant leak or oversight on anything that would require disassembly again.

Hopefully I won't have to do this again any time soon.


BTW, I used the " 8.5 to 11.5Nm" for the TB bolts. That just felt right, and it is clearly tight enough.


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For anyone that has gone through this process, you know EXACTLY what he is referring to above, and I agree that if one eliminated the rear bolt that holds on the "wraparound" duct... you conceivably could remove one of the big catch-22's of this process if you only wanted to clean the TB.

Because of how that duct bolts to the overhead "Supercharged" duct with three bolts, and how tenaciously the connecting accordion hose attaches, just using that one single bolt on the "front" of the duct under the intercooler may be sufficient.

That would make removing and reattaching the hose likely much easier.

Not sure, but just an idea for future efforts.

 

Well, I won't know definitively if cleaning the TB cleared the TB sticking problem as it's hard to prove a negative.... but time will tell, especially once we get back into cold weather later this year which is when it tended to stick more often. But based on previous owners' experience, and just taking in the situation of the oiled and dirty TB, I have little doubt that will clear it up.

But I can definitively say that the car clearly runs better, as it no doubt was suffering from the equivalent of head cold with all that oil saturating the intake tract, sensors and especially intercooler. It has to be breathing a lot easier now, and I can tell as it is much snappier.

Wish I had done this sooner....

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BTW, my average MPG is increased by 1.5ish and instantaneous on the highway is often 2-4MPG better now.... and I've been a fair bit more aggressive with the throttle following the cleaning

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