I have a 2000 XJ8, the check engine light came on a week ago. Also, occassionally the restricted performance indicator lights up. The CEL is always on. The RPI comes on when I slow down or stop at a red light. If I accelerate, it goes out and the car runs fine. The car runs great on the highway. I have been going back and forth to NY from NH 350 miles each way, twice so far without a problem. I checked the forum and got some good advice. I checked for vacuum leaks (to the best of my ability). I found one hose that was repaired with electrical tape that was not looking good. I taped it up solid. No good. I then cleaned the Mass Air Filter Sensor, no good. I stopped at a foreign car mechanic and he scared the heck out of me. I could actually see the dollar signs in his eyes. He said probably all 4 O2 sensors at $575 a piece plus labor. From what I read the back sensors would probably not be the problem. I just want to know what else I can do before shelling out a bunch of dough that I am sure most of will be unnecessary. Also I tried the Lucas Upper cylinder lubricant fix, no good. Any help would be appreciated.

 

Hi,

You have a 2000 (x308) and should move over to that board as this is the X350 board.

You haven't mentioned fault codes. You cannot begin to source the correct problem without having the fault codes read. Restricted performance can be caused by many things, so its a huge guessing game with the odds against you w/o codes. With codes, then the guessing game improves to a more intelligent one.

 

the codes are P0171 and P0174. They say they are lean codes.

 

How do I move to the x308 board?

 

Could a bad fuel filter cause those codes?

 

Hi,

Your post has been moved over already by one of the Mods, so you're in the right place now.

On lean codes, most common problems are air leaks past the MAFS. Take off, examine the L-Shaped intake tube going to the TB. Look at the accordian section for cracks along the seams. Use a flashlight inside the tube in a dark room. If you can see light through the accordians, that's your problem. Tape it up with electrical tape for a TEMPORARY fix, clear the codes, drive it until P1000 changes to P1111 BEFORE taking it in for another test. Then get a new replacement tube as the taping won't last too long.

If all this doesn't prove out, come back for more.

 

Had the same issues on my 99 VDP, cleaned MAF, and so on...
Ended up taking the ignition coils out, to find out that just about all of the spark plug cavities had oil/rust/water mess in them. The back once (closer to the cabin) were almost full with that mess... My valve cover gaskets have gone bad, so I expected a little oil around that area, but not as much as I found, and not as nasty. After cleaning all of them out with paper towels (to soak up the sludge), and some Throttle Body cleaner, and cleaning the rubber spark plug coil sleeves, I’ve had no issues with RPI coming on. The whole thing took about 2hrs to do.

 

I took off the intake tube, there was some oil in it. Is that normal? I cleaned it, checked it with a flashlight, blocked one end and blew into it, no leaks. I notice there is a vacuum accordian type hose with a T connector with 2 connections on either side of the engine and the other to the back of the back of the throttle body. Is it possible that this has a leak?

 

This is perplexing because it only sometimes idles a little rough, and only sometimes RPL comes on at red light or when otherwise starting off, but when I start driving the RPL goes off and the car runs fine. The CEL however will not go off even after disconnecting the battery. I ran another tank of 93 octane with Lucas Upper Cylinder Lubricant and also Gumout all in one fuel injector/fuel system treatment. Nothing good is happening. What next?

 

After checking the tube and putting it back I drove to the post office, when I came out and tried to start it, it kept stalling. I got it running OK then took it for a ride on the open road. It drives great on the road, I come home and it is idling a liitle rough once again but does not stall. Should I try changing the fuel filter?

 

I replaced the vacuum pipe altogether with a similar diameter rubber house from AutoZone. Just trimmed it to the correct size. When I had RPI issues, it was exactly as you described. At idle (especially when coming to a stop at a red light) the engine would start running rough and RPI would show up, but if I was going down the highway, everything seemed OK. I really think you should look at your spark plug coil wells. It takes 10min to get in there.

 

How do you get in there? Do I have to buy any new gaskets first? What has to come off to get in there?

 

In replacing the accordian tube with a rubber hose, how do you get the fittings on the tube? Also, is there a gasket where the intake connects to the throttle body that could be bad?

 

I have had your exact issues and I am still working through it. I replaced the rubber gasket around the throttle body and the air intake tube. No help or change. My car runs fine except for the check engine light and the P0171 & P0174 codes. Very frustrating. I am leaning towards replacing the MAF for the hell of it. Seems to be the cheapest thing for me to do at this point. I did clean the MAF using the directions from fellow posters. It was not dirty at all so I am very skeptical if that will even work. I continue to read all the threads and hope someone has the magic answer for me.

 

Check this link out: http://www.gusglikas.com/AutoRepairPlugReplacement.htm

 

Thanks mzs. I used GUS' site for the MAF cleaning. I am going to look at the plugs this weekend and make sure there is nothing going wrong there.

 

I just wanted to throw my own 2 cents in real quick in hopes that it helps.
My 99 VDP started to get a little shake at idle and would miss a little sometimes not all the time. Then out of the blue it started throwing error lights and the check engine light. Autozone read the codes and I left with a list of no less than 7 codes. So I took it in and had the upper tensioners done and a few other things including plugs and a couple of coils. It ran great for a couple of day so I drove it to Texas (600 plus miles) on the way it started acting up again and on the way home I got every warning the dash can display. Plus it was barely running. I limped home and took it back in. It had a hole in the rubber boot on one of the coils that had gotten worse over time until it was freaking out. The coil was replaced and all the codes went away and the car has run perfect for at least the last 2000 miles. So it could be something very small. It pays to find a good Jag guy that you can trust. Ask around.

 

Have you checked the breather stub and the hose associated with it on the drivers and passenger side? You also need to check the hose from the intake hose to the breather stub. When installing the intake hose make sure the rubber gasket is attached correctly and firmly on both ends. It sounds like you are on the right track. Read this when you get time http://www.gusglikas.com/AutoRepairR...erformance.htm
Good Luck!

 

First let me say thanks, second, I am definitely not a mechanic. But I am sick of getting raped by the dealer. I have gotten nothing but good advice from everyone. With that said, I stayed on the find the vacuum leak train a little longer. I removed those plastic covers once again and re-examined the vacuum hose that I had found earlier with electric tape on it. It looked kind of shabby so I figured I would re-tape it. Upon further examination I followed the hose to its attachment. I could see a lousy electric tape fix but it had a gapping hole in it. I knew all the tape in the world would not help me. I pulled on it lightlly and it came apart. My luck this is the hose that goes from the drivers side front of the engine through the manifold into an area that my hands don't fit, then has a T connector that goes under the throttle body with a continuing hose connected to something attached to the firewall. To make a long story shorter I had to do something. The closest JAG dealer was over an hour away. I got a ride to an auto parts store matched gas line hose to the broken off fittings, got some hose clamps and fished a wire through the manifold to under the throttle body so I could pull the hose through, unbolted the cooling system overflow reservoir so I could get my hands in better, sized it up, cut hoses, pulled the hose through the manifold fitted clamps to fittings and reattached everything. I cleaned up and took it for a test ride (about 25 miles of around town stop and go traffic). The RPL did not come on once. Right there that is a big improvement. The car hums nice. But the check engine light is still on. I will try to unhook the battery and see if it resets. If it doesn't I will still be happy. I learned something and I definitely saved money. Thanks for all of your input. I will let you know the final outcome.

 

I do not know where you are but if you go to AutoZone get them to reset the codes for free. I am not one in favor of removing and reinstalling the battery cable. Glad to see you went forward with it.