Good Evening Everyone,

Soooo I'm on my fourth Jag and this is my first post. Have I been lucky? Maybe. I've never bent a valve, thrown a head gasket, or otherwise, have never had to deal with catastrophic engine failure. 1 tranny rebuild on the '99 XJR V8 SC. In fact, the only time I ever went above boil was due to a sticky thermostat and that was my '99 XJR V8 SC.

Please accept this as my short intro. (couldn't find the intro feed)

__________________________________________________ __________

Now with the issue at hand...

For about 5 days I've been meditating in a quiet corner in my office and under my hood and in the 3000 pages of my service manual. I can't for the life of me find the direct cause of the problem.

The very first thing I noticed was a misfire. Didn't have a scanner with me at this point. I checked the spark plugs and found them to be dirty and changed them to rule them out. Bought premium Denzo plugs $70 and pocket scanner 100$. Changed plugs. Cleared codes. Started engine.

The problem persisted- p0171 bank 1 lean, P0305 cyl 5 misfire, p0316 misfire within first 1000 revs. + RESTRICTED PERFORMANCE @ 4K RPMS WOT

I then decided to clean both MAF sensors as I was also getting a P0171 bank 1 lean code. Before the clean, I was reading .54lbs intake air per minute at idle.

After cleaning the MAF sensors that appeared immaculate I cleared the codes and started the engine.

The problem persisted- p0171 bank 1 lean, P0305 cyl 5 misfire, p0316 misfire within first 1000 revs. + RESTRICTED PERFORMANCE @ 4K RPMS WOT

So I decided to rachet up my approach. (see what I did there?)

I removed the negative battery cable, drained the coolant,
removed the RH Air Cleaner,
removed clean air Y piece,
removed the clean air duct,
removed the throttle body, (was filthy @ air intake elbow with no oil puddle)
cleaned the throttle body (was dirty but not sticking),
removed the RH Secondary Bulkhead panel,
removed the secondary bulkhead panel center,
removed the stabilizer bar,
removed the Air conditioner/heater coolant pipes, ...
and finally arrived at my EGR and of course removed it!

I was hoping to find that my EGR valve was stuck open or completely blocked but it was actually pretty clear. I made it shine inside and out, the solenoid was not stuck or jammed, nor was the valve stuck. Also, I tested that the EGR valve seat made an airtight seal when closed.

Reassembled. Added coolant. Cleared codes. Started engine.

The problem persisted- p0171 bank 1 lean, P0305 cyl 5 misfire, p0316 misfire within first 1000 revs. + RESTRICTED PERFORMANCE @ 4K RPMS WOT

Next, I removed and tested the PCV to intake elbow tube for leaks. It is in perfect condition.

Reassembled. Cleared codes. Started engine.

The problem persisted- p0171 bank 1 lean, P0305 cyl 5 misfire, p0316 misfire within first 1000 revs. + RESTRICTED PERFORMANCE @ 4K RPMS WOT

Please provide any suggestions you may have. This happened from one moment to the next. The engine has never gone over 203- 205 degrees F.

I can provide a freeze frame of my live data if needed. Next on my mind is the fuel filter, or #5 injector, or my accelerator pedal potentiometer going bad.

With KOEO i press pedal all the way down but only get a 78% reading

SOMEONE PLEASE HELP!

 

Welcome to the forums.
You could check the electrical resistance of the the injector. It may be shorted, check two of them and compare them.
Enjoy the drive.

 

Welcome to the forum JOREL.VASCO.REALTOR,

Good to have you with us at Jaguar forums.

I can see you've already found your way to the X250 forum with a copy of your Intro so there's no need for a link to it from me.

Please remember to add vehicle details to your Signature to help others to give relevant advice. Go to the User CP button on the left of the top menu bar, then Settings & Options under Your Control Panel. Select Edit Signature and enter the details.

You can also visit the US Lower Atlantic Region forum by following this link https://www.jaguarforums.com/forum/u...r-atlantic-66/ to find other members in your region.

Enjoy the forums.

Graham

 

Welcome to the forums.

 

Welcome aboard.

 

welcome to the forum - I'm sure the X250 folks will guide you in the right direction so that you can have many happy motoring miles - enjoy!!!!!

 

Welcome to the Forums.

 

Welcome to Jaguar Forums JOREL.VASCO.REALTOR,
Good to have you with us.
Enjoy the forum.

If you haven't done so already you should add your car details to your signature to help others to help you.
If you need help with getting around and using the forum follow this link for some help Forum Help

 

What is the vehicle MY and engine? Below are the cylinder numbers schemes for both AJ-V8 and AJ-V6 engines.

Did you find any oil fouling on the coil unit for cylinder five? It appears the coil is not functioning as DTC P0316 would indicate.

When P0171 or P0174 are present, check for vacuum leaks between the MAF and the throttle body. Check all breather and vacuum hoses for leaks caused by cracks. If you cannot locate the source of the leak(s), have a smoke test performed.

Continually clearing the DTCs is not the approach to take until the source(s) of the vacuum leak are detected and corrected.

 

WOW!! 4 Jags and not a single serious engine problem in the bunch until now.
Good Job!!
Welcome to the forums from ElinorB.
(';')

 

Thank you. I was looking for these.

I was so stressed out with the thought something could have been seriously wrong with my engine internally that I overlooked the ignition coil swap.

I was able to induce a p0303 cyl #3 misfire for the first time ever.

This event coincided with the absence of the p0305 cyl #5 misfire.

The p0316 was present both times misfire within first 1000 revs.

Conclusion- IGNITION COIL WAS FRIED!

The silver lining in all of this is that I gained about 20 HP. Gained through cleaning the MAF sensors, I cleaned the throttle body which was filthy, brushed my EGR valve to a sparkling shine, I sprayed an entire can of intake valve cleaner spray. Next is a good motor oil flush/change.

 

Given the age of the vehicle, it is probably best to replace the coil units and spark plugs at the same time.

If there is any oil present around the spark plug wells, the cam cover gaskets and spark plug boss seals should be replaced.

 

Did you also check the STFTs and LTFTs after the coil unit was replaced?

Refrain from clearing the DTCs until the condition has been corrected.