Tried all the regular things checked all hoses , no apparent leaks not hissing only happens occasionaly flashing yellow and cruise unavailable at the same time all power is lost for a millisecond and then works as normal , the first time I thought my foot had slipped off the throttle and it happens so suddenly and then runs normally. The engine starts no problem and runs perfectly appart from a minor lag about 2000 rpm that some wouldn't even notice. The problem then might not occur for 2 weeks ,but seems not to like heavy rain but could just be coincidence Tried listening with stethiscope spraying round all vacume pipes...... nothing.... looked at brake switch 2 wires only and seemed ok any ideas?https://www.jaguarforums.com/forum/i...s/icon_doh.gif

 

rbsjag, first off, welcome to the Forums. Lots of good information here. But, we do ask a simple thing. Please stop by the New Member Section and tell us a little bit about yourself. We pride ourselves in being a better group that other car clubs around. You will see how this is true. This also gives you a chance to meet those that make this place what it is.

As for your problem, what I would tell you to do is to follow the intake line back and where the intake hose runs next to the throttle body, the plug that goes to the throttle body motor can develop issues and if it looses momentary connection, it can cause what you are seeing. Now, I am assuming that you have the 2.5L or 3.0L engine. If you have the 2.0L engine then this might not be true.

The other issue we have seen is that after many miles, the brushes in the throttle body motor will get short and this results in the brushes not making great contact and this can cause the computer to see the throttle body motor dropping out of the circuit which will cause the cruise to turn off. But, this is normally associated with a check engine light (you don't mention having that light).

The one last thing I would say to check is the PCV hose that runs from the front valve cover to the intake manifold. THis hose is known for developing a split on the backside of the hose (the side facing the engine) and you can only discover this by running your hand on the under side of the hose or simply removing the hose and looking at it. If it is split, it will be obvious. Along those same lines, if you have a smooth hose, I would say to replace it anyways as Jaguar knows this is a problem part for the car and they have a redesigned hose for there that has a ribbed surface to it.

 

Jag x type 2.5 v6 petrol manual 90000miles 38 mpg on a run 29 running arround .
I already checked all vacume hoses with stethiscope and a tube no apparent leaking and sprayed easy start arround to see if any engine note change...nothing... I have looked arrond all the connections on the manifold and everything appears ok.
The car runs without a beat but occasionally (especially when raining heavy but could be a coincidence) it hesitates when acceelerating for a millisecond the engine management light comes on and cruise control measage comes up.
The car then runs perfectly , no missing nothing it then may not happen for two weeks or it may happen 3 times in a row and then perfect.
I did have an error code on the control unit which said knock sensor ( the one under the manifold of course) and I havent done anything about that as I dont know when the plugs or coils were changed on this car as only had it 6 months but the last bloke had it for 7 years and I assume as he wasn't a mechanic he paid for this to be done sometime.

I built rally and racing cars for twenty years so I,m not incapable of doing most things but these dam cars with all this electronic rubbish give me a coil and a distributer and carb anytime

 

rbsjag, from what you are describing, if it is a water related issue, the your problem lies with the ECU. If you remove the cowl off of the area behing the engine bay, on your driver's side, you will see the ECU there in the pocket next to the ventilation filter. You can remove the plug off of the ECU and check to see if you are finding any corrosion on the plug. May even be advisable to put a little bit of di-electric grease in there to help keep water out. After that, it may simply be that your throttle body is starting to get old and the brushes are getting worn which is causing the throttlebody motor to loose its ability to control the throttlebody, which will in turn cause the car to throw some messages at you.

 

Thanks I will have alook at that ... this problem (water filled ecu is common on the big rovers I know) regards

 

The other issue we have seen is that after many miles, the brushes in the throttle body motor will get short and this results in the brushes not making great contact and this can cause the computer to see the throttle body motor dropping out of the circuit which will cause the cruise to turn off. But, this is normally associated with a check engine light (you don't mention having that light).

sorry to disturb you thermo, but my cruise control recently stopped working and my engine light came on when it occurred. can these brushes be replaced easily? Are they affordable?

 

xtype3point0, are the brushes hard to get to? No, not really. Do you need special tools. You betcha. You need what is called a "pentalobe bit". Very similar to a Torx bit (has 6 points to it), but the pentalobe bit has 5 lobes to it. You can buy a complete kit of like 8 bits for around $20. As for the brushes, I am still looking for a place that sells the specific brushes we would need. The big thing to keep in mind is that these brushes have the pigtails that come out the side of the brush, not out the top. So, if you live near a major town with a decent "DC Engineering shop" (aka, alternator/starter rebuild shop), they may have the brushes there. Otherwise, you are going to be most likely finding a brush that is close and then using a little bit of sandpaper to shave it down to size.

The other thing that I find tricky with reassembly is getting the brushes held bad and out of the way as you are sliding the rotor back into place. Not impossible, but it will challenge your patience.

 

awesome response thermo. exactly what I wanted and needed to know. please do post or let me know if you ever find a suitable brush replacement not needing resizedresized. Thanks again

 

Tried that, but you must mean a left hooker not uk spec as took scuttle panel off and no cpu under there .. A word about doing that pull centre out of little plastic buttons (towards the front of panel ) first and then the buttons out hen just put hand under the panel and the screen and work your way accross the windscreen pulling upwards . to put it back put some soap or washing up liquid on the grove it fits into .
As to the continuing cruise control error message and engine management light on the only next thing I can try is to obtain another throttle body and try it and pass on the result

 

Where is the new user section?

 

Massflav,

Go to the top "forums", hovver your mouse over it at the top left then the drop down box will appear and new members forum is there on the right of it.

Good luck, Stu

 

New info:- problem now appears to happen when going up steep hills, hapened 3 times last night only going up hills and no rain so maybe water not an issue ??? I wondered if anyone had trouble with a loose connection and engine movement wa envolved ???

 

Sounds like a misfire. Bad ones make the MIL flash. Uphill is the right sort of time to see this. Probably bad coil(s). Maybe a COP tester will show which.

Another cause of this is that the coil(s) can't get the right power due to a battery on its way out. (An easier thing to test.)

 

This is the identical problem that I was having which, after replacing the thermostat, went away for about 3-months, and has now returned. I went through all the vacuum inspections and replacements, too, and kept getting P0333 and "cruise not avaliable" intermittently without rhyme or reason. Load tested the battery, and inspected all electrical connections - nothing.

Rbsjag - when you have no MIL and no "cruise" message, does this sound familiar? Cold starts OK, then momentarily hesitates (i.e. quick RPM drop), you get the "cruise" message, then the MIL comes on (with only the P0333 code), then the RPMs jump back to normal fast idle? Then after driving a short time, any of the following happens: 1) the "cruise" message goes away after a few minutes of driving and doesn't come back until the next cold drive cycle; 2) the mesage goes away after a few minutes but comes back at or near operating temp; 3) the message never goes away.

 

rbsjag: I had someone change the plugs 10K ago and they put in the hated Champion plugs and I had a P0303, and misfire under low speed load and a intermittent "no cruise" , found two of the six bad, put in a new set of NKG's and it runs like a top. Ohmed out the coils and did a compression test, ALL ok. Also had upper and lower o rings done at the same time as HE did the plugs. I dislike Champion plugs now even more.That's why I don't like other people working on my Jag.

 

Well... bought secondhand throttle body and fitted yesterday and so far so good, been out and reved nuts off and so far no problem but I will keep you all posted. I intend to strip the old one to look at these brushes to see if they are worn and if so if it is possible to replace them and with what brushes and pass the info on