1999 Jaguar XJR 4.0L Check Engine Light On

1999 Jaguar XJR 4.0L Check Engine Light On

I recently had an issue on my XJR with the CE light on, and after a couple cheater resets, (battery disconnect) with no success, the light came back on after less than 100 miles.

In my past life, I was a mechanic with heavy experience in Jaguar, but after being out of the trade for nearly twelve years, a lot has changed. Without the OBD II scan tool, I was dead in the water. Naturally, the car failed the annual NYS emissions inspection, and the shop I brought it to did not want to touch it. So, rather than go to Jaguar and have my eye teeth ripped out, I figured I would go in up to my elbows myself, again.

To start, I knew that I needed to first retrieve the DTC(s) that were stored in the memory, but without the tool, this is impossible, it’s not like the older GM’s where you could jump a couple pins in the OBD port under the dash and get the light to flash the DTC’s, or the Chrysler cycle the ignition on and off three times, and also read the flashing DTC’s . Those were the days. While not really conclusive, this at least gave you a starting point, if you were too cheap like me to go out and buy the scan tool. Heck, back in the day, the OBD scan tools were over a thousand bucks for a decent one, and I was not sure I would get enough data out of it to make the money back in repairs to justify the cost. Now days, the price has come back in line with something reasonable. I looked at that internet and late-night infomercial CarMD cheapo, and figured that would do the job, so I asked for it for my birthday from my kids. Well, that wouldn’t do, my kids thought it was cheesy, so they chipped in and bought me the Innova CanOBD2 3130 unit. Good choice, and in the long run, the extra $$ was a better deal anyway.

Read the manual, which s something I always do, and I highly recommend that if you buy anything that comes with a manual, follow the rule: RTFM. (read the *blank*ing manual) It will save you time, and possible damage to the vehicle, tool, or injury to your person. People laugh, but it always works. After that, plug it in and follow the instructions—turn the key on, but DO NIOT START the vehicle. Let the machine do its thing, and get your codes.

Now on to the reason why you probably even started reading this article. My DTC’s showed P0400, (EGR circulation out of limit) P0507, (Intermittent high idle) and P1111 (system check complete). I figured to go with the simple first, and pull the EGR valve to inspect, especially since my car has 90K + miles on it, but it sits most of the time. In the past, I have seen many, many EGR valves get stuck for one reason or another, and that was a good first start, and it turned out to be right on the money. The valve, although a miserable job to get off the car, was plugged solid.

Please understand that this article and/or my statements here do not in any way take the place of any smart idea that it might be to have a qualified Jaguar or otherwise certified technician evaluate and repair your vehicle, here’s what I did, for what it’s worth. If you venture in to do this job on your own, good luck, but please consider having the job done professionally, it may be better for you in the long run, and I cannot be held responsible for any advice, good or bad, given here. Thanks for understanding.

If your car is the supercharged V8, like mine, the plumbing on the top end is going to be intimidating. The blower is big and cumbersome, and the throttle body is mounted in the back, and the EGR valve is located--you guessed-it—right on the back of the intake under the throttle body. Follow the flex tube from the RH exhaust manifold right back to the valve. I almost closed the hood right there and went out and bought a For Sale sign for the car. Well, not really. I like the car too much.

Roll up your sleeves, and prepare to get banged up. The valve has to come off, and you have to leave the top end pretty much intact, which in itself is somewhat bittersweet. You can and should remove the plastic tunnel from the airbox to the top of the TB, and some of the plastic valance on the firewall in order to even get a half a glimpse of the EGR, and you will probably want to have an inspection mirror to see some of the stuff you have to take off.

At this point, I know what you’re thinking, “just remove the throttle body altogether and I can see the whole thing.” Don’t do it. The TB is a pain in the neck to reinstall and set up after you restart the car. I highly recommend that if it is still on the car and it runs, leave it there, and fight your way around it. That’s the bittersweet part. You don’t have the added hours and aggravation of undoing all the complex aspiration hardware on the top end of your motor, and then putting it all back on again and hope it still runs. But, leaving it all together has it’s downside, the valve is buried. Hope you have smaller hands, or get your ten-year-old son to do it for you. The good news it that other than the cramped working conditions, it is really not that terrible to get the valve out.

Start by removing the flex tube from the right bank exhaust manifold that goes to the EGR valve, and put it off to the side. With the mirror and a good light, you can then see the two bolts that hold the valve to the intake. But before you go taking them out, go around to the other side of the car and carefully disconnect the connector from the EGR sensor located on top of the valve. It may be a little tight to get off, but do not force it, press the latch on the connector and gently wiggle the connector out, try not to pull on the wires too much, or the connector will come apart. If necessary, a little persuasion with a small screwdriver to pry it out might help, but again, carefully. While you’re there, you can also gain a few precious millimeters of working space by also disconnecting the connector to the TPS. Next, there are two small coolant hoses that go to the valve body itself. Remove them as well, also being careful, they are molded formed hoses only available from Jaguar, so you don’t want to go tearing or cutting them. A little finesse and a small hose hook should free them. After that, go back around to the right side of the car, and you can take out the bolts holding the valve to the intake, and it should fall out in your hand, almost. If there is a lot of carbon buildup, like on mine, you may have to wiggle the valve out a bit.

You may find the valve ports packed with a mucky, hard, burned-on mixture of oil and carbon. Mine was plugged almost solid on the valve itself, and into the port on the intake. See attached pics. I am surprised that the car ran at all, the plunger on the valve did not move at all. Big decision at this point, either replace the valve altogether or just try to clean it. In my case, I chose to clean it, rather than replace, (best price I could find was $363 for an aftermarket valve) so here goes, if you want to try my way. Take the valve body and back to your workshop and start the cleaning process.

 Valve out, before...

Disassembled, before...

Could have been the problem...

 Now, there is a lot of opinion out there about using a cleaning agent or not. Some say gasoline, some say brake fluid (?) and others say a can of carburetor cleaner. I suggest the carb cleaner. You might want to start with a small catch basin of some type, a bowl, cup, whatever, to collect the dripping carb cleaner/muck mixture. You can in the initial stages re-use the collected carb cleaner to re-clean the valve. Remove the three small bolts that hold the electrical sensor, coolant loop, and EGR valve to the elbow housing. Pull the sensor/loop/valve carefully out of the housing, being careful not to damage the plunger on the valve. Do not try to pull the plunger out of the coolant loop, leave it intact. Spray the plunger assembly generously, allowing a little time to sit and soak in a bit. This will loosen some of the buildup for easy cleaning with a probe, wire brush, scraper, screwdriver, knife, or any combination of these. Start scraping off the buildup and re-spraying the carb cleaner after a few passes. Clean it well, it will be better off if you can try to restore it to like-new condition, or as close as you can. Do the same for the elbow housing that the valve sits in. I found that going to hardware store and get a small wire brush that plumbers use for cleaning copper pipe (3/4 diameter) works well for cleaning those ports. Once you are happy with the way the valve looks, including cleaning the seats and mating surfaces properly, put the small bolts back in to reassemble the valve body into the housing, and go to work on the intake port on the car.

Elbow housing, cleaned...

Valve plunger, a whole lot better...

Back together, now ready to re-install...

I found that if you put the gas pedal to the floor to wedge the TB wide open, (use a cut broomstick or other rig…) you can see far enough down into the intake to do a little housekeeping. I noticed that there was a little excess motor oil laying in the back of the intake, which I am sure contributes to the buildup in the EGR. I am not sure how much oil is too much, but I will change the PCV valve later just to be sure. With the TB wide open, you can use a small probe to clear away any carbon buildup or deposits from the back side of the intake. If you have a small vacuum or care to fashion a small nozzle for your shop-vac, (I used a piece of ½ inch copper pipe insanely duct taped to the end of the shop vac hose) you can try and vacuum out the mess by inserting the nozzle down the throat of the TB while scraping with the probe, and also with that ¾ plumber’s wire brush from earlier on. Once all is cleaned, be sure that the mating surface where the EGR housing meets the intake manifold is cleaned, and using new gaskets if necessary and a very little bit of RTV blue silicone sealer, put the whole thing back together. Reconnect the hoses, wiring harness, and the flex tube, check the coolant level, and mechanically, it’s back together. Then, reinstall the plastic airbox tunnel to the top of the throttle body. One more note on the coolant level, in case you are not aware—even though it looks like you didn’t lose all that much when disconnecting the hoses the first time, you should still add the half a cup or whatever. Just that much loss is enough to throw on that pesky “Engine Coolant Low” message in the speedo display with that scary red light.

Before starting, use the scan tool if you have one to clear the DTC’s from the computer. You can do the old battery-disconnect trick if you want, but the scan tool application will be better. DON’T FORGET THAT IF YOU WEDGED THE THROTTLE OPEN TO CLEAN, REMOVE THE WEDGE and allow the pedal back to the original idle position. If you don’t do this and try to start the car, have your wife call 9-1-1 after she hears the fighter jet run up in the driveway, followed by a loud bang, and sees the fireball and ensuing smoke cloud. Also have her wait for all the engine pieces to stop falling from the sky before she goes out to see if you are still alive.

Once over everything you took apart one last time to make sure that you put it all back together correctly, and then pray to your God and ask for grace. Now might be a good time to also repent of your sins. He will be merciful to you. Don’t look back, and turn the key. If the car starts and runs, you got a real good chance that you will be soon motoring down the highway. However, you won’t know for sure now until you drive the car for a hundred miles or so. The ECM will not complete all its run tests until a driveability test is complete, and it takes about that long. If you go a hundred miles with no CE light recurrence, success, and congratulations are in order. You just saved yourself about $1000 at Jaguar or your trusted brave (and confident) mechanic.

Keep the shiny side up…GWD