P0302, P0305, P1314, P1316-- 2 coils fried at once, or other issue?
 

I'm driving home at ~80 kph when suddenly the engine starts to misfire, but I'm able to keep up a speed of ~45 kph with the throttle pedal almost to the floor, misfiring all the way. It would idle fine. I had to drive it a further 5 km to get home. When I got out of the car I noticed steam coming from underneath. It was about -12C with snow still on my driveway, which accounts for the steam, but a steamy catalyst I'm sure......

I couldn't get to the car for a couple of weeks, but was able to check the codes today:

P0302--cylinder 2 misfire
P0305--cylinder 5 misfire
P1314--misfire rate catalyst damage fault--bank 2
P1316--injector circuit/IDM codes detected

Last fall I replaced spark plug number 6 after getting a new coil and still having a misfire. So now I'm wondering if somehow coils 2 and 5 fried at the same time which led to the other codes, or spark plugs 2 and 5, or anything else? What is an IDM code? I haven't heard that term before.

The engine started easily today, but when I rev it past ~ 2500 rpm it gets a bit rough.

Any erudite and experienced assistance from this awesome forum is absolutely appreciated! :)

P1316, I had that code when I removed my manifold. It was caused by the injector electrical plug not being fully seated. Something to check anyway.

Could be a number of things but I'd be concerned about the cat on bank 2. No power above 30-40 mph is a pretty common symptom of a blocked cat.

A jag P1316 is simply listed as excessive misfires. I would be suspicious of coils given the history and I would try a mass swap to see if I could isolate one or two bad coils.

Yes, moving the coils makes sense. But AlanG reminded me of something: the last time I had the XJR at the specialist mechanic, he needed to undo the exhaust to replace the hanger bearing bushing, and mentioned there was some grey inner bits coming out of one of the cats. He suggested I might want to remove the cats and replace them with straight pipes. This would not be safety certificate compliant, but would only matter if and when I want to sell. We have no emissions testing here.

Hmmm, if a coil or two went bad and caused enough of a misfire along with a 5 km drive, could I have overheated a degrading cat enough to cause the P1314 code?

Hi JYIVEZ

You might want to check my thread below You may find it interesting and of some help.

https://www.jaguarforums.com/forum/x...n-coil-114871/

I just changed out Cyl #5 coil and found oil in the spark plug well, today I'm about to replace the cam cover gasket and the spark plug seals. All this came about because of a P0305 code.

I hope this is of some help to you

BigBossRadio
Dallas Tx

Yes, when they go they go :(

You can certainly remove the cats but you will get a check engine light and at least one or two codes because the O2 sensors expect a change in levels pre and post cat. I don't think this will effect the way the car runs but in my area of the US you can't get an inspection done if you have a CEL on, even though my car is exempt for emissions testing :(

It was the fact that you said the car starts and idles normally but has no power above a certain rpm that made me thing of the cat. That plus the steam generated by a red hot cat all points to the same conclusion :(

Give the cats a good bang with a rubber mallet and see if you hear a rattle. Remove the cats and look inside you should be able to see if the honeycomb structure is damaged.

Excellent advice everyone, many thanks! And thanks for the link to your thread BigBossRadio, very helpful.

Hmmm, not sure if I want to be driving around with a CEL light on all the time due to removing the cats. But the alternative isn't pleasant either.

I won't be able to get to checking things for a while due to work commitments, but I'll post back once I've sorted things out. Thanks again gents!

Had a similar issue with my XJS (check out my story on the XJS forum.

Clear the codes and wait for them to reappear. You will likely only get 1 coil misfire code as well as the cat code. That's the one to focus on.

I had three coil codes thrown. It was only #5 that was the problem. I had a broken spark plug!

I thought I should finish this thread by posting the final outcome of this problem.

I let the car sit for quite a while due to lack to time, them finally got to it again. Battery is now dead. Replaced it, fully charged, and the car started right up. I cleared the codes and took it for a drive. No change. It took a while for the CEL to light but now the codes say mutilple misfire on the OTHER catalyst bank, plus cylinder 3. Huh?

The NGK plus less than a year old (installed by the Jag shop) were covered in hard black deposits, so all cylinders are running rich. I replace the plugs with Champions.

I swap coils 1 for 3, clear the codes and drive. No change in performance, CEL illuminates again, code says cylinder 3. Huh x 2!

I call my Jag mechanic and he sends me to the exhaust shop. Diagnosis: misfires have overheated one precat which embolized it's innards into a mid cat. Solution: open up the pre cats, whack out all the catalyst material, replace both mid cats with a resonator, custom fabricate a Y-pipe and reconnect to the factory mufflers. So now it looks like it still has the pre-cats for our visual-only safety inspection, the 4 lambda sensors are still hooked up, and it's as quiet as factory. Yay!

So off I drive, and it won't rev past 3500, bucks and misfires, yet idles fine. Arrrgh! Code says cylinder 3. Double and triple ARRGH!

I swap coil 3 for 4 this time, clear codes, drive, CEL says multiple misfire and cylinder 3. I can drive at most 25 kph, so I drive from the exhaust shop to the Jag shop with my hazard lights blinking.

Jag mechanic says OK, time for some diagnostics: compression is fine on all cylinders; timing chain is good; already replaced timing chain tensioner is fine; coil low voltage wiring looks OK. His suggestion is to replace the crankshaft position sensor, as the original one was used when he installed the "Andy-bracket." A few days of waiting for the part, and it's installed.

And now, drum roll please..........it's perfect! Lots of power, revs to redline without issue, still factory quiet, and NO CEL! I had it up to 190 kph and it ran beautifully. Yay! But what a runaround. I never thought a failing crankshaft position sensor plus a plugged exhaust system could give so many whacky codes, but there it is. I'm running through a tank with Amsoil PI gas additive now just for peace of mind, then I'll check the plugs and hand calculate the fuel consumption. What a pleasure it is to drive when it's running right!

Not one thing it's two things that are another.
 

Okay sorry to say that I apologize for my punctuation. So I don't use my normal keypad I just use the talk to text on the phone because it seems to be a lot easier than, trying to put in punctuation and whoever else this works. So furthermore. Salvage title yes. How the car has a salvage titled unknown what happened to the vehicle why was salvaged unknown. As far as I know it's a Jaguar X-Type. So the fuel pump has been replaced with an aftermarket pump works great. 4 out of the 6 coils been replaced due to not being able to find the coils in my location and having to order them out of state and still waiting for my other two. The car decides to have a gearbox fault engine system management fault. And throttle position and throttle position pedal codes .Code 1229 shows up. Sure which I am unsure what the code is for. So I try to make it sound a little more easier to read and I'm from Minnesota so so you betcha and whatever else is northlanders say......... As far as I can tell the vehicle needs a new throttle position sensor which is unavailable and I should buy the whole throttle body assembly. what anybody can help me with that thank you.

If it is a 2002 it's not a X300 , The VIN # will tell :

https://www.jaguarforums.com/forum/vindecoder.php

2002 Jaguar X-type
 

So I have reset it the computer. When you first turn on the ignition and said engine fault management and gearbox fault there is no pedal when given gas.The throttle position sensor /pedal A a low input code, after ran for a bit. Just finish doing spark plugs 6 brand new coils and fluids change in transmission and motor.