Hi all,

Ongoing project of my X Type 3.0 Estate. I've changed all the gaskets for the upper and lower inlet manifold, IML's, breather hose (all the usual suspects in terms of seals failing/aging and letting in air) and also spark plugs and ignition coils with a noticeable difference in smoothness and responsiveness in the engine. However, fuel economy with a good 70/30 motorway/in town mileage is barely 20mpg although previously with the same mileage mix I've hit late 20's. And also sometimes when I start up the car it dies if I don't press the accelerator and even so is very lumpy for about 10secs before evening out, a couple of times a week.

Given they're 20yrs old and I tend to replace what I think could be a problem or potential problem (yes more money that sense clearly!) I'd like to change all of the 4 sensors. However, I'm baulking at spending £100 plus per sensor on the OEM Denso's which as I understand it are;

Upstream; Denso 234-9029

Downstream; Denso 234-4798

Does anyone have a good experience with alternate, good quality OE's that are more in the region of £50-£60? there seem to be plenty on Ebay but real life experience of them would be appreciated with links or part manufacturer/number please.

It's a bit confusing in terms of Jaguar part number but again as I understand it they're;

Upstream; C2S51801

Downstream; C2S38497

Is that right? Replacing them seems relatively straight forward if you can wrangle the access and they're not melted in (fingers crossed!)

Thanks in advance for any responses.

 

They can't be the problem you say at start up as they're not used till (say) 30 secs so the engine/exhaust have warmed a bit.

When you have poor MPG on e.g. motorway why not monitor fuel trims? But first check it's running CL (closed loop) as it ignores the O2s if not and "guesses" (approximates) fuelling.

Also check all OBD monitors are happy. (Pending code) P1111 says so; P1000 says not. If P1000 find which monitors are unhappy!

You could have a dirty MAF (so fuelling can't be calculated properly) or some such.

 

Thanks for the response, much appreciated! I confess I don't understand fuel trims or how to monitor what is good or bad so I guess I need to get my head around that. I do have an LR V2.0 reader but it has some weird anomaly whereby it won't talk to my X Type on some things if I go through Engine Diagnostics selection but I think it does fuel trims through the standard OBDII option so I'll try that. By the way I have tried everything including updating the system, wiping it completely and starting again etc. but it just doesn't work on the Engine Diagnostics bit.

Do you either have a complete idiot's guide for what I'm actually looking at/for or another thread that explains it in very simple terms. The way you've written your helpful response I'm interpreting it as it has to be live connected whilst driving and I assume get someone to film the OBDII scanner on the fuel trim bits? Sorry stupid questions! I'm fairly handy on a DIY level but have never gotten into anything other than reading and erasing codes in terms of code readers..

 

Sorry and how do I check/know it's close loop and again what does that mean. Apologies don't expect you to spell it out but any signposting to other threads or stickies that make it simple even for me would be appreciated!

 

https://www.jaguarforums.com/forum/x...-there-250657/

https://www.jaguarforums.com/forum/x...please-252752/

https://www.jaguarforums.com/forum/x...-218050/page2/

Etc, all available in SEARCH

 

Focusing just on the part about looking at live data: I have a cheap bluetooth scanner that connects to the free app Torque Lite. Turn the car on, open the app, go to Settings menu where you can choose to set up data logging. Available channels include short and long term fuel trims. Go back to Settings and hit Toggle Logging to start recording then drive around normally while it records the data. When you stop the car hit Toggle Logging again to stop logging. Then you have the option to upload data to the Torque app site where it will show you a graph of what happened while you were driving or you can look at the data in Excel or Google Sheets or any other software you like that reads comma separated variable (CSV) files. Your code reader most likely has the same capability. I find this easier and safer than trying to look at live data while driving.

 

I looked up your LR V2.0 manual, it looks like you just drive the car with the scan tool connected then when you stop you select "Review and Report" from the main menu. The user manual is pretty light on info so there may be more to it than that but the device is capable of logging data without resorting to filming the screen while driving. Good luck!

 

Easier to check trims when parked!

Engine hot.

At idle & again at about 2500rpm.

 

Please use oem Denso's. We put aftermarkets in mine and it still threw up the codes. Replaced with Denso's and codes went straightaway.Not a job you want to be doing twice. Apparently Our X types are very sensitive to oxygen sensor band widths.

 

Luckily I went Denso in the end and only changed the upstream ones. Bit steep but now they're changed. Weirdly one at the front was the absolute nightmare for me, my hands are wrecked such a tight squeeze, rear one was fairly easy and luckily for me neither were rotted or rusted in. I've noticed an instant improvement in smoothness (car used to have a slight hesitation on acceleration especially from standing start) and I'm checking the fuel economy on a full tank of petrol as of yesterday. If I get 25 mpg or more with mixed driving then I'll be happy!

 

Thanks for the info. I know the X Type can be a little fussy with which scanner it's linked with so not sure if it's the same in terms of the Bluetooth scanners. Do you mind sharing link or model with the one you bought so I know it works for sure?

 

You weren't wrong about the sensors not being a solution for the cutting out. The car did it again the same day I'd changed the sensors. I think as close as a pattern there is it tends to do it if the car is still warm from a previous drive, not noticed it from stone cold before. Suggesting maybe something, a split or crack or whatever opening up after being warmed up? Car revs dips up and down like crazy with the engine going on a hunt then cuts out. Then usually starting up again straight after perfectly fine with normal revs as if nothing happened.

I've changed vacuum pipe that goes from manifold to throttle body, brake booster vacuum pipe. Breather hose looks ok but replacing with silicon anyway next week. Sorry repeating myself also all other inlet manifold seals changed including IMT, also soaked the MAF in cleaner. There's one other vacuum pipe see photo (the one from just behind air filter hose to firewall) that I haven't changed. Anyone know the name/part number and whether it's prone to failure? Any other know weak points as the symptom i.e. cutting out suggests an air leak? If I don't get anywhere else with this may invest in a new MAF...

 

Do you mean the brake booster line there, the one with the inline check valve? That is Jag p/n C2S17552. Inexpensive aftermarket parts are available, .

Mine was broken on arrival, previous owner had patched it with RTV. I broke it again myself, it is very brittle.

 

No that's the one I've replace for belts and braces, it' the other pipe in front of it, anyone know what it is?

 

That goes to the Evap purge control valve. When the purge valve opens the manifold vacuum pulls the fuel vapor from the gas tank into the manifold to burn it. If you had a problem with that pipe you would get a check engine light for an evap system leak so yours is probably good.

 

mountian, been fighting similar battles with both of my estate / wagon projects so feel you on this. One other thing to check is the vacuum line that runs under the intake to the Fuel Pressure Sensor. It connects to the back of the intake below the brake booster port and runs to the fuel rail at the center. The boots on either end tend to split in ways that aren't immediately obvious. Also the very thin vacuum line inside the plastic cover can easily split if not handled gently. Be aware that the end on the sensor is permanent and can break if you pull too hard. If you break it, the intake has to come off again to get to it. If this is leaking it can cause a slight vacuum drop as well.

also agree with everyone above concerning the 02 sensors. All four need to be the Denso pieces. I've tried Bosch (almost as expensive), part store branded options and the cheap ebay versions. The car hated the Bosch (codes, miserable running), woudn't run on the part store ones and burned up the ebay specials in a few thousand miles. Given the pain of triple installs and cost to "get a deal" the Denso price premium seems cheap now.

As to monitoring fuel trims and O2 operation, the torque app and an inexpensive bluetooth module is the easiest I've found. You can also log with it. The "gauges" are easy to add to the main screen and should show most everything you need.