Hey everyone, I'm new to this forum so I'm sorry if I'm not doing this right lol.
I have a few questions for you Jag owners.
So, I recently purchased a used Jaguar X-Type 2004 with a vacuum leak problem as well as a DSC System Fault.
I have been driving the car every 2-3 days for a month now despite the CEL. When I first gassed up I used 91 Octane Supreme gas since I had read that putting lower octane gas in a car like this could damage the engine. After maybe a week of putting supreme gas, the engine started "stuttering" that's the only way I can describe it. As soon as I push on the gas pedal a little too hard from 0km/h to 30km/h the car misfires or something.
So, my question to you guys is: Am i damaging the engine by driving with the vacuum leak? Also, does the drop of performance have anything to do with me putting supreme gas with the leak? I have reverted to Regular gas because of the performance and because my fuel efficiency has declined heavily. Half a tank lasts me 1 or 2 days max. Will putting regular gas for a short while damage my engine? I won't be using it this winter so it shouldn't be too bad.

Sorry I'm all over the place but i am a newbie both to Jags and Cars in general so bare with me.
P.S even with these problems I absolutely love this car

 

If by 'stuttering' you mean misfiring, you must correct the misfire(s) or damage to the catalyst(s) is the result. Under no circumstances should the vehicle be operated under conditions that cause the MIL to flash as catalyst damage is occurring.

Use the search function on this forum to search for threads concerning vacuum leaks and how to repair them as this topic has been discussed many times before.

 

Lets see if we can help you sort it out. Have you had the codes scanned and written down. It is very important to know the codes. If you haven't had it read get it done as soon as possible and post the numbers so we can better see your problems.
You state that you have a vacuum leak. That needs to be resolved as soon as possible. Continued driving with a vacuum leak and driving with the lower octane will damage the engine and just as important you can do permanent damage to the catalytic convertors. Does the CEL flash when it is stuttering? If so that is a signal that you are creating a damaging situation to the convertors.
With the regular fuel and the vacuum leak you are probably driving the Engine Control Management System bonkers. The vacuum leak is going to show lean so the ECM is adding fuel to correct the mixture and the Knock sensors are registering the lack of octane and the ECM is changing the timing to correct the fuel firing and is just bouncing in circles chasing the problems the fuel and vacuum leak are creating. Hence the stuttering.
The 4 main sources of a vacuum leak are:
1. The PVC hose running from the front cam cover to the intake manifold.
2. The brake booster line on the back of the intake manifold running to the booster. There is a round check valve in the center of the line and it swells and cracks.
3. The IMT O-Rings located on the end of the manifold. The large round plastic/black objects.
4. The intake manifold seals.
None of the parts are particularly expensive but the manifold seals are a bit of work to change.

The DSC problem can not be diagnosed without a reading of the codes. It could be a speed sensor, fuse, wire but without the codes there is no way to know which one.

Get the codes read as soon as possible and get back to us.

 

Thank you very much for your response. The codes are P0171 and P0174.
The CEL never flashes which is why i still occasionally drive the car.
I will not be using the car this winter and will repair it as soon as winter is finished.

 

Adam47, you mention you have a 2004, you are a little bit of a unicorn per se. What I mean by this is that there are 2 different wiring harnesses to the car. If you open up the driver's door, there is a sticker in the lower corner (near where the back of the front seat would be). That has the build date of the vehicle. Is it on/after April 2004? If no, then you really have a 2003 vehicle as you have all the features that a 2003 vehicle has and most likely was actually built in 2003. If it is after April 2004, then you have the revised version and you have a slightly different wiring harness than the earlier vehicles and there are some differences (mainly the transfer case was changed to a more reliable setup).

As for the codes that you are seeing, this is saying a vacuum leak. I would first check the big 3 like what Avern1 states. Odds are, that will fix your problem. If you don't want to just be throwing parts at the car with the hopes of finding the problem (granted, most of these parts are pretty cheap), then what you can do is first check the PCV hose. This normally splits on the underside where the hose rises over a bracket by the throttlebody. If you have a smooth hose here, replace it. This is a known problem with the X-Type and the new hose is ribbed and will ensure you don't have issues in the future.

From here, I would say to either use a can of starter fluid or a cigar. With the starter fluid, start the engine and let it idle. Spray the IMT valves, the vacuum line going to the brake booster and any other vacuum line/joint you can manage to hit. When the engine RPMs pick up, the starter fluid got in to the engine and that is a source of your leak (possible to have more than one). With the cigar, you start with the engine cold and the a/c-heat turned off (this ensures the engine fan will not start). From here, you get the cigar lit and take a good drag off the cigar. You will then gently blow the smoke into the engine bay and watch it wander through there. When you see the smoke make a sudden directly change, it is pointing at your vacuum leak. This is especially helpful with the lower seals on the intake (hard to hit with the starting fluid).

If you need additional help, let us know. We have all had this sort of problem. Part of what to expect with owning an X-Type.

 

Thermo
Thanks for the in depth answer! Much appreciated.
As far as the sticker you speak of, I can't seem to find it. So I'm not sure about that.
Thanks for the cigar trick, I thought I needed a smoke machine. I will be performing the test this weekend. I will let you know what the outcome is!

 

Adam47, where the front and rear doors meet, this is referred to as the B pillar. If you open the driver's door and follow this pillar down to where it meets the bottom of the car, just above that point, there should be a sticker there with a bunch of information on it. If there is no sticker there, then at some point the car was repainted (most likely from an accident). This is where you may have to go to the Jaguar site and put in your VIN number to determine the build date. Jaguar has a section for owners and you can get some basic information about your car there.

 

Okay I found it. And it is in fact an 03 since it was built in December of 2003.
Thanks Thermo!

 

Adam47, ironically, you actually have an early 04 X-Type. Yes, it was built in December 2003, but they started building the 04's in the October 2003 time frame to use up the earlier parts as much as possible. So, you have the viscous coupled transfer case. Some see this as a plus, some see this as a minus.

 

Adam: Welcome to the forum!

The link below is to a thread with pictures of what Avern1 and Thermo describe, because these vacuum leaks are common problems, fortunately with simple, inexpensive solutions.

https://www.jaguarforums.com/forum/x...lights-149671/