Hi All,


I just joined and posted an introduction. Not sure if this is the correct place to post for some advice. If not let me know and I will do it correctly.


I obtained a 1997 Jaguar xj6 with 250,000 miles on it and I live in Minnesota. It was a company car so I have all the records and most of the bearings have been replaced so it is in good shape. The previous owner told me it was stalling and running rough. When I picked it up, it started and ran smooth and he thought it might have been bad gas. I drove it 50 miles but it had no power. Engine light was on and owner told me that the catalytic converters were throwing a code. In a few days I went to start it and it would not idle but it would run smooth at high rpm until I let off the gas, then it would die. Once it was warm it ran ok.


I decided to put in new plugs (old plugs were nice light brownand clean out the throttle housing and put in a new air filter. I put in new cam cover gasket (leaking oil) and removed all the injectors and had them tested and cleaned. I also removed the EGR valve and cleaned the plugged tube and other build up. New seals in the injectors as well. took off the crank position sensor and cleaned it up.


After all that, started up and still ran rough. Codes that I got were 1206,206,300,306,302,1313,1314.


I checked all the coil packs and they ohmed out ok but I got a new one and swapped things around and the codes never changed. Put some of the old plugs into cylinder 2 & 6 and nothing changed.


I checked for vacuum leaks but found nothing and did not hear anything.


I admit defeat. I guess the o2 sensors orthe catalytic converters mightbe the problem, or maybe I should throw some sea foam in the gasand run a tank first? looking for some ideas.


thx,


Tom

 

Fix your codes one at a time simple obvious stuff first. I had a string of codes on my mercedes that were all sensors out of whack from a cracked vacuum fitting. Careful with the fog kits, additives etc. Ive seen them wipe out sensors. They usually dont do much more than give you a false sense of accomplishment. I did a quick results on your codes list. Most seem to be misfires. I think 3 were to cyl 6. Could be a bad injector or connector or wiring. Two seem to point to catalyst. If your o2 sensors are bad I should think at some point there would be an "out of range" type code relate specifically to the sensor at fault. I guess it depends on how long its been since your codes were cleared. and how long its been driven since cleared. Id write down the codes you have. Clear the ecu. Drive the car on a few errands. Recheck the codes. Pull their definitions and see if you get an idea for an "upstream" issue. Codes that take much longer than that to record are probably resultants of the primary issue(s)

 

Just my 2 cents worth.

At the mileage you have the O2 sensors are past their use by date. Down here that is recommended at 160K kms (100K miles).

My Black S started funny stuff, and lots of items checked as you have done, and NO codes, NOTHING.

Brain finally kicked in and I fitted 2 new Pre Cat O2 sensors, sweet as ever. Car only has 94000kms on it, so logically not due for a long time, but it came from a state known for rubbish fuel.

 

Ok, thanks. I took out the pre-Cat o2 sensors and left them connected and started it up. It ran smoother and only two codes were left 300 and 306. I'm thinking the catalytic converters are plugged. Since I replaced cylinder #6 coil pack and spark plug and swapped out several coil packs and I'm getting power, is there any other check I can do for that cylinder? the plug was nice and light brown to gray when pulled.


regards, and thanks to both of you.

 

The possibility of plugged/restricted cats will reek havoc. Same as a blocked exhaust of any type.

If any engine cannot breath, IN or OUT, issues occur, and that was before codes etc were even invented.

Here (due to no emission testing) we simply gut the cats, and carry on. Some are easier to do this to than others.

I've not studied the X300 system, but it should not be too hard to bypass the cats to prove a point.

 

Unlike most other cars, the X-300 uses post cat lambda sensors for primary control and pre-cats for check sensors, so I do not know why you are getting the "results" you are from disconnecting the pre-cats. I suspect it is a red herring, though.

 

Some markets only have two O2 sensors. And it gets confusing because the 'post cat' sensors are of course between the primary cats and the floor cats. If you haven't spotted the primary cats you might think your post cat sensors were pre cat sensors.

 

Thanks again, before I go gutting the cats or by passing them, is there any way to there any way to test the o2 sensors and/or tell if the exhaust is restricted? I will try clearing codes and go for a longer ride and see what codes show up.


Thanks,


Tom

 

I do see 4 sensors but I took out the two closest to the engine out . My only thought was that with them out, there are now two holes that allows exhaust to come out reducing some of the back pressure and maybe that allowed it to run better.


Tom

 

Ross,

I know we've discusssed this before, but I can't remember if the X300 O2 sensors can be checked with a good high-impedance DVOM, or would it require an oscilloscope? Can you tell us? According to the AJ16 Engine Management System manual, once the sensors are hot (500C, which should be reached in about 20 seconds after engine start), the voltage from each sensor should swing between 0.015V and 4.89V. Can Tom see that DC swing on a good DVOM, or will he only be able to read an average voltage (maybe as an AC average) ?

Don

 

Today I took it out to the store and back. Same codes 1206,206,300,306,1314. I tested the injector #6 resistance and continuity to the main relay but was not able to check pin #2 continuity to the ECU as the pin locations I have must be wrong. The manual I have only has the pin connector for AJ12. Anyone know the pin connector locations for the xJ6 ECU?

Not sure if I'm going about this correctly. Also thinking about checking compression of # 6 cylinder.

Thanks,

Tom

 

Tom,

PM me your email address and I'll send you the X300 Electrical Guide which shows ECU (ECM) pin identifications for both the 6- and 12-cylinder cars.

Don

 

all of those code appear to be misfire codes. At least based on a 5 min search i just did for each one. The ones that are specific point to cyl 6. Hold heavy paper or a flip flop or something over each tail pipe while the car is running to accentuate the misfire. If its rhythmic even if it just a string a break and then a string its consistently one cylinder. if its completely random then its more than one. But if it were my car I'd pull cyl 6's injector connector
(if you can I didnt go look at the car) and go do the tailpipe test again. If the sound hasnt changed youre close. Your first code specifically says there is a short or open circuit to cyl 6. Somewhere on here is a list of jaguar codes. if there isnt a code for a dead injector, and the open circuit is as close as it gets it may just be a bad injector. But inspect the connector inside and out and the wiring to it as well.

 

Don- A high impedance DMM is fine to measure the voltage, but it is harder to see the voltage "swing" properly. You can watch the feedback signals on a charting OBD scanner and get a pretty good idea if the lambdas are working- they should go from high to low at least every second or so. On the other hand, if they do not swing, either by voltage reading or with the scanner, it might have any number of root causes.

I am always suspicious of culinder #6. The coil wire lenghts for cylinder 5 and 6 will lead you to the wrong connection. Cylinder 6 wire is supposed to have a yellow tape.

 

Thanks, I will give that a try, I will have to look close at the injector connector to see if I can remove the rubber part to get the connector out of the rail. I just took all the injectors in for cleaning and testing and they all came back in good shape, but you never know if it went dead now or if the wiring was bad all along. I will let you know how the paper test works...kind of cool idea.


Thanks

 

Taking the opportunity of Grant's post:
"Here (due to no emission testing) we simply gut the cats, and carry on. Some are easier to do this to than others."

Here, due to no emission testing, is almost the same.
I want to "gut" the cats.
The car is a 3.2 X300 with one sensor downstream the cat per exhaust bank.
Reject the cats is an easy job, what about the O2 sensors?
Somebody with expirience on O2 simulators?

 

The quickest way to test the oinjector circuit (barring using a scope) is a "Noid Light". Google that.

 

Success!!, today I tracked down the wiring on cylinder #6 and verified continuity to the ECM/ECU for the injector #6 (thanks to Don for wiring manuals). Everything checked on and even though I just had all the injectors cleaned, I decided to swap out the injector to see if I had a bad one. When I started to take apart the fuel rail I noticed the clip on #6 injector was not seated properly. I adjusted that and put things back together and all codes are gone and the car runs very smooth with good acceleration. Man the smallest things... that stupid clip issue cost me at least 30 hours. but I'm happy now. thanks again.


Tom

 

Hi Tom,

Hmmm.... If you are describing the small metal clip that aligns the injector so its twin orifices are properly aimed at the backs of each intake valve, it would be very surprising to learn that your problems were caused by the clip not being fully seated and the injector being improperly aimed...

Or was it the electrical connector for the injector that was loose?

Don

 

After I had the injectors cleaned and assembled the injectors back in, I had trouble getting those metal clips in place ( not the electrical connections). As I was trying to get the # 6 injector metal clip back in place today, if I moved it a certain way, gas sprayed out. My guess is that the clip not in the correct place allowed air to get pulled in and too lean causing misfires. The injector had been seated too far in and needed to be pulled back to get clip in place. If it shows up again and the clip is in place, then I have an intermittent electrical connection to the injector that got temp fixed as I worked on it.

Drove 50 miles today and no issues.

Tom