XJ ( X351 ) 2009 - 2019

What did you do to your X351 today?

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  #141  
Old 05-11-2020, 11:47 AM
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I finally got round to replacing the upstream o2 sensors and the ******* passenger side center o2 sensor that absolutely did not want to come out. It was completely mangled by the time I got it out. Good thing I've been working out more recently. The downstream and driver side center sensors were replaced last year.

I was planning on getting 400 cell cats fitted. I wanted 400 over 200 because I wanted better flow but didn't want a huge increase in exhaust volume. Well, now I've decided I don't want ANY increase in exhaust noise at all. I like the exhaust tone and volume just as is and any louder would be too much for me. So, the high flow cats are out but I would still like to fit new OEM style units if possible, seeing as my stock units are now nearing 120k miles.
 
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Old 05-12-2020, 08:41 AM
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I’m thinking about changing my cats too. Unfortunately I have to get CARB-certified ones. So it’s Jaguar cats or Magnaflow only for me. Super expensive.

Also was wondering if anyone with older cats is able to see any air restriction in the form of long-term fuel trims. If you wouldn’t mind, could you post yours? Both my banks are headed negative without any codes. Thanks.
 
  #143  
Old 05-12-2020, 11:10 AM
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Originally Posted by Nedoerr
I’m thinking about changing my cats too. Unfortunately I have to get CARB-certified ones. So it’s Jaguar cats or Magnaflow only for me. Super expensive.

Also was wondering if anyone with older cats is able to see any air restriction in the form of long-term fuel trims. If you wouldn’t mind, could you post yours? Both my banks are headed negative without any codes. Thanks.
I also am at the mercy of CARB but I was planning on just keeping the OEM cats and swapping them back in every two years.

I'll check on the fuel trims next time I'm out.
 
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  #144  
Old 05-14-2020, 07:18 PM
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Thanks that’d be great.

I went ahead and bought some CARB certified Magnaflow cats. Darealwoody on these forums pointed out they were ~40% off at hoonigan (don’t change that 1st “n” to an “l” like I did on my work computer). I’ve never ordered from there before and their online ratings/comments are weird, so I’ll let you know if I get them.

All the best.
 
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  #145  
Old 05-18-2020, 09:36 AM
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I don't have CARB needs, but wondering what Magnaflow PNs you're purchasing? I'd be interested to hear your anecdotal installation experience also, in general I've had good experience with Magnaflow but I'm hoping you can post a sound clip too
 
  #146  
Old 05-18-2020, 11:40 AM
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I can now also confirm that the X351 takes the X350/Stype/Lincoln LS/Thunderbird type front upper control arms. They are absolutely identical. But accessing the bolts is much harder on the X351 due to the ridiculous Jaguar engineers and their ridiculous ideas. Yes, lets put one of the passenger bolts underneath the fuse box, which barely has any give at all. And yes, why not PURPOSEFULLY cover up one of the driver side bolts with a molded piece of plastic bulkhead? They could have molded the bulkhead AROUND the bolt, but no, there is a purpose-built bulge in the bulkhead specifically to cover up that bolt, thereby necessitating the complete removal of several pieces of bulkhead with their tiny screws hidden all over the darn place. Well, damn that...I used a chisel and hammer to destroy that stupid bulge. I don't know what these people are thinking sometimes.

Anyway, I also was able to remove the springs from the old struts but I'm having a hell of a time trying to put it all back together with the new upper mounts and struts, as this is my first time messing around with springs. I think I may just take the pieces to a shop and have them put it all together. What would probably take me all day will probably take them a few minutes.
 
  #147  
Old 05-19-2020, 01:48 AM
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Originally Posted by dmchao
I don't have CARB needs, but wondering what Magnaflow PNs you're purchasing? I'd be interested to hear your anecdotal installation experience also, in general I've had good experience with Magnaflow but I'm hoping you can post a sound clip too
I bought a CARB-certified direct fit Magnaflow cat for the driver side (#5561070). I bought it from Hoonigan (much cheaper) but it still shipped directly from Magnaflow. Arrived in 2 days after the order. The passenger side cat is back-ordered. They also sell non-CARB certified cats or universal cats for much cheaper.

Im not sure whether these will provide a big performance benefit, I’m just hoping to restore exhaust flow and prevent the ECU from messing with my fuel trims.

I tried to install it yesterday, but those bolts are on there real tight. The upper bolt is also pretty poor access. Trying to get penetrating oil in there and heating it up without a 4-post lift was too difficult, so I gave up and sent it to the local muffler shop. I think you need an impact wrench and penetrating oil minimum.
 
  #148  
Old 05-19-2020, 04:01 PM
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I'm curious to know how much louder the exhaust will be after install.

I wrapped up the installation of the front shocks and upper control arms today. I was able to find a local shop who put the struts and springs back together with the new shock mounts for just $40 cash. The short test drive went well. Front end feels nice and tight again, so much so that I can feel the rear flopping around. Now I'm looking into replacing those shocks soon.

Interestingly, the bushings in the upper control arms seemed to be in good shape and the old shocks seemed OK too. Further test drives will reveal whether my 50-70mph steering wheel shimmy is really gone or not.
 
  #149  
Old 05-20-2020, 03:59 PM
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Originally Posted by XJ8JR
Front end feels nice and tight again, so much so that I can feel the rear flopping around. Now I'm looking into replacing those shocks soon.
Whaddaya know? Rockauto just got the OEM Bilstein 44240578 air shocks back in stock for a really good price (relatively speaking). Looks my suspension will tip-top by the time I have to resume my daily commute.
 
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  #150  
Old 05-21-2020, 07:45 PM
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Driver side cat is installed. Passenger side is still back ordered. Exhaust sound is minimally louder under full throttle. I didn’t install a high-flow cat, as I needed to be CARB compliant. A normal Magnaflow cat would likely be better at improving sound.

Muffler shop did the cat swap in < 1 hr using a breaker bar and some penetrating oil. So I guess I just need to work out more.
 
  #151  
Old 05-22-2020, 02:37 PM
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Any change in throttle response or performance?
 
  #152  
Old 05-24-2020, 12:12 AM
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Originally Posted by XJ8JR
Any change in throttle response or performance?
Yes, performance seems improved for me. I can now peel out for the first 1-2 seconds from stop with TC off and dynamic mode on. I wasn’t getting that before. So I’m happy. Will replace passenger side cat whenever it ships.

I am pretty sure my cat on the drivers side was getting clogged as I get ~10 misfires on bank 2 at startup each morning. Am also running rich on that side. Absolutely no idea why as I have no codes, no problem with leak down test, and almost everything has been changed (coils, plugs, injectors, o2 sensors...etc). Cat change didn’t improve that either unfortunately, but short-term trims are now switching faster and are in agreement with bank 1. May send out oil and coolant for analysis in my never-ending quest to figure this issue out.
 
  #153  
Old 05-25-2020, 01:16 PM
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Originally Posted by Nedoerr
I am pretty sure my cat on the drivers side was getting clogged as I get ~10 misfires on bank 2 at startup each morning. Am also running rich on that side. Absolutely no idea why as I have no codes, no problem with leak down test, and almost everything has been changed (coils, plugs, injectors, o2 sensors...etc). Cat change didn’t improve that either unfortunately, but short-term trims are now switching faster and are in agreement with bank 1. May send out oil and coolant for analysis in my never-ending quest to figure this issue out.
That's an odd problem. I hope you get it sorted soon.

I installed the new rear air shocks yesterday. It is a royal pain in the butt trying to get the threads lined up properly within the strut mount holes. And then its another huge pain to get that lower shock bushing to line up within the control arm so that you can slide in the bolt. All in all, it took about 4 hours. I also discovered that my OEM spare tyre won't fit over my new big brakes, so that's out of the boot permanently.
 
  #154  
Old 05-25-2020, 04:03 PM
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Bet it rides like new
 
  #155  
Old 05-29-2020, 05:34 PM
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had the exhaust shop remove the stock backboxes (mufflers) and replace with their own custom ones.

this is loud and not to everyones taste but its percect for me and sounds almost identical to a range rover svr
 
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  #156  
Old 05-29-2020, 11:29 PM
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I just finished replacing the rear sway bar bushings with Powerflex units. I always suspected that there was just barely enough room to get the job done without having to drop the subframe and all that. It was a pain in the butt for sure and took about 3.5 hours but much easier than the factory recommended way. Finally, having smaller hands is good for something! There's no way on earth the big burly ham-fisted dudes would be able to do this job.
 
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Old 06-08-2020, 02:01 PM
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I replaced the front inner and outer tie rods yesterday. The outers seem to still be in good shape but the balljoints on the inners were extremely loose and barely had any grease left. Not sure where the grease goes since the bellow covers were in good shape and properly clamped. Now its time for an alignment.
 
  #158  
Old 07-06-2020, 01:14 PM
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Last week I started getting the Low Coolant warning but the level wasn't dropping and there were no leaks anywhere so I figured the float in the tank had gone bad. Replaced the tank and its all good again.

I still haven't been able to cure my steering wheel shakes at 70mph. I had the wheels balanced for a 4th time and the tech couldn't find anything wrong in the suspension (no kidding, I've replaced everything already).

This steering wheel shake at 50-70mph has been driving me nuts for months and its getting to the point that I don't like driving the car anymore. I've done the following:
-new upper control arms
-new shocks/shock mounts
-new inner and outer tie rods
-new wheel bearings
-both lower control arms, sway bar endlinks, and sway bar bushings have all been replaced within the past two years
-new wheels
-alignment
-wheel balancing on Hunter Road Force machines 3 times at two separate America's Tires and once at Firestone. The first two attempts improved it but the 3rd made it worse. Now thankfully Firestone got it back to where it was on the 2nd balancing.

Each tech says the wheels are not bent and the tires (General G-Max RS UHP summer) are fine but no one wants to take the time to try turning the tires 180 degrees and rebalance. My gut tells me its the tires but I'd hate to waste money on a new set if that doesn't solve the issue. I guess I could check the steering rack bolts although I think that would produce a different type of vibration at all speeds. Steering rack bushes, maybe? I'm stumped.

A bit of history on this debacle: Back in January 2019 I decided to ditch the Bridgestone all-seasons that were on the car when I bought it. I sourced a set of PZeros in slightly larger than stock sizes. While getting the wheels balanced, I was informed that one of the front OEM Mataiva wheels was bent but still balance-able, and I was not experiencing any symptoms (no shakes or vibrations), so I went on my way. Everything was fine for the next 6 or 7 months until I installed the thicker XJR sway bar. That introduced a massive amount of understeer and tramlining so I decided to downsize the tires back to stock size and sourced a set of Michelin Pilot Super Sports to see what all the fuss was about. I absolutely hated them. They followed every single line in the road, the handling was sloppy, and the car always felt like it was flopping from side to side. I will say however that they handled high speed corners superbly. Other than that, they felt downright dangerous. I tried all sorts of different PSIs, had them inspected and rebalanced, and they were still garbage. After a month, I threw them away and got the new set of General GMax RS. Huge improvement! I could drive safely again. While getting those installed, the new tech again informed me that one of my OEM wheels was bent, but I still did not have any symptoms...until sometime this past December/January when the steering wheel started to shake. So I bought a set of aftermarket wheels from a member here but still had the shakes. I've been chasing this beast ever since.
 

Last edited by XJ8JR; 07-06-2020 at 01:32 PM.
  #159  
Old 07-06-2020, 04:33 PM
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What a pain! It does sound like you changed everything.

Two more random thoughts:

1) Are you using factory original lug nuts? Apparently very few aftermarket lug nuts engage the wheel to the hub correctly.

2) Have you looked at whether your wheel well plastic is loose, slapping your wheels when you get to higher speeds? Maybe someone could drive next to you and see if there is anything obvious.

Hope you get to the bottom of it soon.

All the best.
 
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Old 07-06-2020, 05:10 PM
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Originally Posted by Nedoerr
What a pain! It does sound like you changed everything.

Two more random thoughts:

1) Are you using factory original lug nuts? Apparently very few aftermarket lug nuts engage the wheel to the hub correctly.

2) Have you looked at whether your wheel well plastic is loose, slapping your wheels when you get to higher speeds? Maybe someone could drive next to you and see if there is anything obvious.

Hope you get to the bottom of it soon.

All the best.
Thanks. I had thought of the lug nuts. They are the acorn type that fit aftermarket wheels. But then I remember that this issue arose while I still had the OEM wheels and lugnuts, which leads my gut back to thinking its got something to do with the tires.

The wheel well liners are in nice and tight, and unfortunately I don't know anybody qualified enough to be able to spot an issue while driving.


 


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