I have a 1996 XJ6 that is misfiring on all 6 cylinders. What I think I need to know is what should my crank position sensor ohm out at. My coils ohm out good so that leaves me with the crank position sensor and timing. Speaking of which, what is the procedure for timing this engine. Thanks in advance!

Scott

 

Scott:
First- Welcome to the forum. There is a good bit of X-300 knowledge around here and only some BS!
The CKPS has a specified resistance, but there are many reports of intermittent failures even when the ohm reading is correct, so I will not even bother to look it up in JTIS.
Look for the FAQ and find the service manual download if you wish to look further.
The CKPS is regularly reported as a cause of no start, or, less frequently, misfire, so you are quite possibly on the right track.

Timing is set by the ecu and is not adjustable. A fellow on several other forums who uses the handle "XJRENGINEER" sells a modified CKPS bracket that advances the timing 5 or so degrees, as I recall, and it is reported to give a performance boost.
Anothe possibility after the CKPS is corrosion in the ecu harness connector due to water ingress. The ECU is in the right side kick panel.

Good Luck, an please report back with your results!

 

As Ross said.

The crank angle sensors usually go "legs up" at about 100k miles, NO idea why, they just do. Mine did at 176000kms, and in the driveway, so no real embarrassment.

Are you 100% sure it is ignition??, not doubting your diagnosis for one minute, and not the injection system having a hissy moment, and giving your mis-fire. Not a common thing with the AJ16 Nippon Denso system, but anything is possible. The "cam angle sensor" (the thingy where a distributor used to live), may be mistimed, which the Nippon usually works out (it is that clever), but there are some notations appearing lately of this unit starting to play up. This sensor sets the "sequencial injection" timing on this engine.

Some misfire is caused by "lean fuel", which is nearly always related to a neglected fuel filter.

Unmetered air in the intake system reeks havoc on these engines, so make REAL SURE that the trunking (post airflow meter), oil cap seal, breather hose/s etc are ALL 100%. Usually more of an issue at idle than at higher revs.

FORGOT, you are NEW, WELCOME, and since fun is already being had, ENJOY.

 

Grant,

By post air flow meter, are you refering to the device attached in the middle of my intake manifold that I am backfiring through? Lol. But seriously, I can hear air rushing out around it.

Thanks in advance!

 

Um, the airflow meter, as I call it, it mounted in the intake trunking (again what I calls it).

There is a short LARGE hose from the aircleaner, then the air flow meter, then a rubber connector hose attaching TO the 90deg elbow, then the bellows hose that attaches to the throttle housing.

OK, got that sorted.

Attached to that elbow is a hose (about 5/8" diam), and that is part of the breather from the camcover, VERY common to split and leak.

The intake air temp is also attached to that elbow.

The bellows hose is REAL COMMON for leaking, now that old age is creeeping in. The numerous clamps also need to checked for proper fitment and security.

The fact its backfiring through the inlet is scary, and obviously needs sorting quickly.

The TPS (under the throttle housing), and a PAIN to get at, are also now getting to be a common failure item, and they control the fuel, and backfiring is "usually" a lean mixture, mmmm.

I have heard of the plastic elbow splitting where the mount lug is, due to some fool not lining things up proper, and forcing the thing into place.

The fact you say you are hearing "air rush through" indicates to me you got a BAD air leak. Go through EVERYTHING, very carefully, and systematically.

 

Here is the part that the backfire is coming through. I am a bit lost on what it is.

I did change the fuel filter today and the old one was def shot. But there is still a misfire and it alternates between cylinder after I erase the codes. Any help would be more than appreciated.

Good Day!

Scott

 

I do not know how you decided where your backfire was occurring, buit the pictures depict the EGR valve/\
Grant speaks the Australian dialect of the english language, so his referencce to trunking that is "post mass airflow sensor" refers to the piping system or ducts donstream of the MAF, like the bellows connected to the throttle body.

 

I got the "trunking" Grant was refering too. As in the trunk for a central unit in our homes. I though that was the EGR valve, but was afraid to go get a new on. Thanks Ross. That clears up a lot. As far as the backfiring, there is a seam between the lower part of the EGR valve and the upper part. That is where the backfiring is occuring. I am gonna look into a new one this evening. I gues my only real question is, will this fix the problem? or is the backfiring through the EGR a result of some other issues with the car. As far as the air intake tube, trunk, it is solid. No air leaks there. Again, thanks guys for all the help!

Scott

 

I got the "trunking" Grant was refering too. As in the trunk for a central unit in our homes. I though that was the EGR valve, but was afraid to go get a new one. Thanks Ross. That clears up a lot. As far as the backfiring, there is a seam between the lower part of the EGR valve and the upper part. That is where the backfiring is occuring. I can hear it and see it when reving the engine from under the hood. Trust me, I know where it is coming from because I jumped...lol...not to mention the rush of air that is coming out of the gap at over idle RPM. You can hear it, feel it, and see the condensation shooting across the intake manifold. I am gonna look into a new one this evening. I gues my only real question is, will this fix the problem? Or is the backfiring through the EGR a result of some other issues with the car. As far as the air intake tube, (trunk), it is solid. No air leaks there. Again, thanks guys for all the help!

Scott

Below is a pic of the EGR valve and circled in red is where it is seperated and backfiring through.

 

Yep, we Aussies talk funny, life goes on.

BEST PART

We dont have EGR, so no idea what you are facing with that thing, BUT, if its leaking, its broke, so a new one is needed.

Go with the guys in your region, they will be very familiar with it.

 

Actually, I find your dialect rather elegant, not funny!

 

I don't know if anybody else picked up on it, but, that EGR valve should have been replaced under the EGR valve recall. Call your local dealer and see if the campaign is still open for your car. If it is open, go get it done. If that dealer won't do it, find one that will. Those valves were problematic. I wouldn't bet that it fixes your running concern, but at least you'll have a new EGR valve.

 

I checked with a local Jag shop and all dealer recalls and servicings are on list for this vehicle. Apparently the previous owner took greak care of this care.

I replaced the EGR valve and that helped a little. Now I am showing "multiple misfires" and unrecognized DTC when I run the codes. It only does this after the care has warmed up. I am stumped still, but sure it will be figured out.

Again, thanks to all that have contributed to me getting her running correctly. If anyone can think of anything at all, post it please.

Scott

 

Why not post the DTC's?

 

did you ever get this resolved?