Friends,

I recognize there is a ton of advice on this forum for some of all of my codes, but I thought Id list them anyway to see how experts might approach them. Can runs smoothly. Then misfires and RESTRICTED PERFORMANCE. Then starts up cold runs smooth for several miles, then misfires and resticted performance.

These these codes:

P0. 171 Too lean bank 1

P0. 174 Too lean bank 2

P0 300 Random misfire

P0 301 Cyl 1 misfire

P0 302 Cyl 2 misfire

P0 308 cyl 8 misfire

P0 351 Ignition coil A primary control circuit open

P1111 Intake air temp sensor circuit int high voltage

Where do I and by tech begin?

Thanks!

 

Look for air leaks that will occur when engine starts run bad.

 

P1111 is NOT a fault.

 

See Bob's comment on P1111.

Maybe P0351 is an issue needing immediate check: look for a broken wire going to the igniter on spark plug #1 (right side closest to the front of car).

Then run a couple of cans of a good cleaner (Gamout or Lucas or SeaFoam) to clean the injectors which are spitting and not spraying.

Searching for leaks along the intake system is a given. Lots of way to do it: unlit propane torch always worked for me.

A bad temperature sensor in cross over pipe creates all sorts of fueling gremlins. Dirty MAF too.

 

I'd be checking for vacuum leaks and air intake leaks since you're getting lean codes on both banks. Check the full load breather and the accordion part of the air intake tube for any cracks. If you get air leaking in between the MAF and the throttle body, it'll lean both banks out.

Cylinders 1 & 2 are the front 2 on the right side of the car, 8 is the rearmost on the left side. Check that the plugs and coils are not in any obviously bad condition and address if you think so. You can swap the coils between 1&2 to 3&4 and if the codes change from misfire in 1&2 to misfire in 3&4, then I'd say thats a pair of bad coils and replace them. Ditto in #8, just swap that coil with another one on that side and see if the problem moves.

Not sure if the 351 code refers to just the coil on the #1 cylinder or if its the entire bank on the right side (bank 1).

 

the cover to the coils is removed on both sides and left off.

Could that be a clue?

 

Len, definitely put both the coil covers back on *after* you investigate cylinder #1 (P0351). Those coil covers do keep heat in but, it will help keep moisture/water out. I would pull the #1 coil out and see if there’s any oil/moisture in the spark plug well. If there’s only water moisture in there, I’d highly recommend pulling all 8 coils out and get it throughly dried out. Pulling the boots off of each coil to also dry off would be a great idea. I just wipe them down with a clean and dry cloth. Another way to help moisture from causing a misfire is dielectric grease where the little spring meets the very top of the spark plug. Obviously it’s much easier to apply it to the spring vs the top of the plug.

I want to add to what Bob said earlier about P1111 not being a fault. I’ve encountered miscellaneous scanners/code readers that will display the air intake temperature int high for that P1111 code. Fortunately for you the *real* P1111 code means all the tests have passed for emissions reasons. If you were to clear all the other codes and/or perform a hard reset, that P1111 code will turn into a P1000 code. So in the future when you see P1111 code, just ignore it entirely when you post codes on here so someone won’t inadvertently talk about it like I just did. 😂

I know you’ve been on here awhile so I’ll spare you the basics. The brake booster vacuum port (which I believe was mentioned earlier?) is part number:
C2S15816
The plastic quick connect ring is almost guaranteed to un-assemble itself the moment you touch it and the rubber o ring inside the brass insert will be petrified and is a very specific size. The original brass insert for all intensive purposes is left alone. It’s also possible the intake manifold, part load breather and the 2 black air pipes going to each side of the intake manifold need new gaskets/o rings. Just some food for thought.

 

So we ruled out leakage. No vacuum leaks. Smoke test showed nothing. Coils and plugs all checked out clean. No differences when they were moved from one cyl to the next.. Compression test was normal.

What we believe is a wire in the harness to the coil as the source of the on-again-off-again misfire is in cylinder 1, front passenger side. When the cover is off the coils, there is no problem. Put the cover back on and the problem CAN reoccur. Right now the cover is on and the engine is running fine. No CEL.

Poss fix: What we'd like to do is avoid replacing an entire wiring harness to all coils, and run a pigtail connection from the coil/cylinder no. 1 back to the harness at the rear of the harness thereby bypassing whatever the troubled wire may be causing no. 1 to misfire now and then.

I probably didnt explain this well because I am not a tech, but that's what I understand from my mechanic.

Is this possible? Can I purchase such a 4-pin pigtail with about 24 inches of wire?

Other ideas? Suggestions?

Thank you.

 

Dorman 645-940 is 19.4” long

 

And compatible with our cars?

 

Well, a Standard Motor Products S2527 fits on a 2002 Toyota Camry 4 cylinder and the same SMP S2527 fits on a 2000 Jag XJ8. I’m not sure why the Dorman isn’t listed for the Jag but, if it works on the Camry, it’s gotta work on the Jag.

 

The Jaguar uses DENSO engine management so many Toyota parts will work.
The starter/alternator shop I trade with uses Toyota parts (Denso) to repair my alternators.
The Toyota parts are easier to find from suppliers.

 

So we replaced the ignition wires to cyl 1 whch were dry..

Smoke test showed no leaks

Cleaned MAF.

Compressional test- normal

At first, engine starts and idles normally. A few good miles and then restricted performance. No code for a bit.

Then these codes:

0301 cyl 1 misfire. (Wire was replaced). Coil is good and clean. All were checked.

1313 misfire /catalyst fault

1316. inj/IDM codes detected

0351 ignition A - primary cont. circuit open Cyl 1 ignition wires were replaced

After ignition wire replaced these are gone:

P0. 171 Too lean bank 1

P0. 174 Too lean bank 2

P0 300 Random misfire

P0 302 Cyl 2 misfire

P0 308 cyl 8 misfire

Car can start cold no misfires. Then they come on gradually.

I'm out of ideas.

 

Tell us about what kind of spark plugs are installed, gap and when they were changed.

I would write with a sharpie on each coil top the *current* cylinder location so you don’t get lost with what coil went where. Ask me how I know that 🤪. After that, I would swap coils from cylinder #2 & #4. Then go to the other side and swap #8 & # 6. Clear all the codes and rerun the test. Post what misfires (if any) returned.

Are these the factory Denso ignition coils or an aftermarket set?

 

Your P1316 meaning is probably wrong - check you have the Jag meaning for your model.

BTW best to include the letter (P, C, B, U) as each could be a 1316.

 

Here is the Jaguar DTC guide for 2001 to 2003 AJ27.

 

If all of these codes started popping up one day, you should check the electrical system to make sure you're getting the proper voltage to run the electronics. Get out the multimeter and check the battery voltage, then start the engine and see what you have. If there's no change, it's more than likely the alternator. If it goes up, but below 13.5V, then do the tests in the attached. At 13.5 things should run fine, but 14.5 is the target voltage. Also, how old is the battery?