2003 Jaguar X-Type 133,000 mi. I have a major problem on my hands. It just recently got cold and my problems have not stopped. At first my car was cranking up rough and my check engine light came on so I had my spark plugs replaced since I hadn't already. After I had my plugs replaced I started getting the "engine system fault" and "gearbox fault" messages. I took it to the shop and 12 codes came up. I was told to have the Mass Airflow Sensor replaced first and possibly the intake manifold gasket. I had the mass airflow sensor replaced and it still didn't solve the problem. The mass airflow sensor code is gone but it is still misfiring from all cylinders and codes p0121 and p0174 are coming up. Just got back from the dealership and they are recommending replacing the throttle body ($1965), clean injectors and induction system ($275), replace cam cover gaskets and all spark plugs ($932 not counting the fact I just replaced plugs less than 1,000 mi ago) and replace oil pan gasket ($1192) for a grand total of about $4500). On top of that these repairs are just so further diagnosis can be performed! Any ideas on what my problem may be? I can't pay that much for repairs on a car I'm still paying for. Please help me!!!

 

mrcjr, you can get a brand new throttle body for $1110 through http://www.jaguarparts.com. I doubt there is $850 worth of labor there as getting to the throttle body is really easy and putting it on I am sure you can do it. The only thing I would not be sure about is whether it needs to be programmed to the ECU or not. I wouldn't think so, but I could be wrong. I am trying to find out inside of the JTIS, but not having much luck at the moment.

Now, with that being said, have you checked your IMT valve o-rings and there is a vacuum hose under the cover (inboard of the throttlebody) that tends to develop leaks. Either one of these can cause what you are seeing.

I wish you lived near Southern MD, I would tell you to come on down and we would look over the car. Granted, I somewhat think the dealership is taking for your atleast part of a ride because why would you need to replace the plugs already? If you installed some double platinum plugs like are recommended, they shouldn't be a problem already. And the valve cover gaskets, unless you are loosing oil, I wouldn't worry about them. That is $1000 right there that you are saving. As for the oil pan gasket, sure, it is probably nice if you could stop that leak, but right now, I would be worried more on getting the car running right and going from there. That's another $1200 savings.

What you seem to be describing is all related to an intake leak. Hopefully someone else can come along and state whether you could simply replace the throttlebody and go from there. First, I would try pulling off the intake tube and using some throttle body cleaner, give the throttle body a good spray down. Make sure to open the throttle body by hand to get the back side of the throttle body. Yes, your car will be slightly harder to start the first time after this and probably will not want to remain running, but you have essentially flooded the car. Step on the gas pedal a little bit and the computer will make it all better in a few seconds. For the $5 or so, it can't hurt. If that isn't it, I would do some calling around and see what junk yards want for a throttle body. I'm sure it would be much less than even $1100. From there, a local auto mechanic could match the throttle body to the ECU should that be needed. Mounting it on to the car is 4 bolts and 2 electrical plugs along with a 3" hose clamp. Not that hard of a job to do.

 

I'm curious. Did all these recent problems begin shorty after the plugs were replaced?

As Thermo indicated, P0174 is typical of an intake vacuum leak. To change the spark plugs, the intake manifold had to be removed. To remove the intake manifold, the throttle body was either unbolted from the manifold and allowed to "hang" in place or it was removed along with the manifold. Either way, there were plenty of opportunities to introduce a vacuum leak at the joint between the upper and lower intake, between the throttle body and the manifold, or at any of the vacuum lines that had to be disconnected to liberate the upper intake manifold.

If the throttle body was removed with the manifold, then it had to be electrically disconnected then reconnected. At some point, Jaguar was having problems with tin plated electrical connectors making good connection. This could be the issue with your throttle body.

If this were my car, I would check for vacuum leaks at every joint and connection that was disturbed to get access to the plugs. I would also disconnect, clean (with electrical parts spray) all electrical connections to the TB. There are simple electrical checks that can be performed to verify if the TB is bad or not. I would like to believe the dealer did these checks before recommending a new TB for almost $2K....but then again, business is business.

If your TB really is truly bad, there are cheaper alternatives to replacement by the dealer. Right now, there are two companies on EBAY that are offering to rebuild yours X-type TB for about $400. Just search EBAY for "Jaguar throttle body". I have no idea how reliable they are, but at least one offers a lifetime warranty. The obvious issue is your car is not drivable for a week or two (they claim it takes two days to do the rebuild, plus shipping time in both directions).

If you ultimately determine that your TB needs to be replaced, I would be interested in taking the bad one off your hands. I'd like to determine what the failure mechanism is and what could possibly be done to repair these failures.

Mark

 

The "gear box fault" started occurring after the spark plugs were replaced, however the check engine light was on prior. Its funny I wasn't having any acceleration problems until I had the plugs replaced. I had my personal mechanic perform the spark plug replacement so I'm not sure what procedure he used, I'd have to ask him. I would think the dealer would have been able to diagnose if there were any of the problems that you mentioned with the throttle body. Then again business is business.

 

mrcjr, a lot of shops have gone away from the days of troubleshooting and proving a component wrong to a philosophy of "here's a list of parts, replace them one at a time until the problem goes away". That is the beauty of this forum, we know what breaks and we try to prove the part bad before replacing (atleast that is how I try to do it). Saves money in the long run, but is the "harder" way to do it. The shops make a lot more money because now they are getting you for the labor on the part plus they are making some money on the parts too. So, they are essentially double dipping. Come on, tell me that the shops are buying the parts at what the dealership is charging you. I don't think so. Just something to keep in mind.

You want to watch a shop squirm, ask them how they proved the part bad before they replaced it. If you know anything about mechanics, you will see them start tossing the flag. Another thing is to always ask for the old parts back. Then, when they start giving you the "well, that didn't fix it", you ask the question of (with part in hand), what made you think this was bad, show me. The honest shops will give you an answer and will know in the future that they can't BS you. Therefore they will take that little bit of extra time to prove the part bad and save you money in the long run.

So, keep the questions coming and we'll take things a step at a time.

 

Definitely sounds like the dealer added on a lot of other maintenance things to their estimate not related to the problem at hand. Not that that is wrong, but at least they could have expalained what everything was and how critical (or not) to get it fixed immediately.

Not to sound like I am defending a dealer, but in a way I can almost see their point in replacing every possible part that COULD be related to the problem as a lot of people today would be ticked off if they brought a car in and work was done and the check engine light wnet off and everything seemed good only to have it come on a couple days or a week later. Dealer doesn't want them to feel they did a bad job. That's why it is such a blessing to have a mechanic, whether it's at a dealer or independent shop, that you can trust; almost like a doctor. Customer needs to understand what will be initially done and that it may or may not fix the problem and that there is a possibilty the underlying problem might not be totally fixed. It might be a bit more hassle that way, but less expensive as you are not replacing stuff needlessly. Electrical/vacuum problems can be pretty tricky.