Hi, all - been a while since I've bugged you but I've got a bit of a pickle on my hands that I can't seem to figure out. I really appreciate all the past help folks have given and would also appreciate it if anyone could chime in here as well.

It seems I have engine misfires on bank1 at high RPM (not necessarily load related).

Info:
2002 x-type w/ 75K miles (new plugs all around less than 4k ago)

Symptoms:
A few days ago, while driving at highway speeds and hitting the gas to pass, the engine would sometimes (more often than not) get incredibly weak the higher the RPMs went. Soon after the weakness began, the check engine light would blink and the car would rev-limit me below 3,000. Naturally, the car reminds me that cruise control is not available during this time... just because she is sassy like that.

To help diagnose what's going on, we hooked up a code reader to the OBDII port and learned the following:

• When RPM is near or above 3,000 in park (NO load) the ECU will throw P0301, P0303, P0305, P1316, P0300 and P1313.
• When RPM is at 2,000 with car in DRIVE (HUGE load on the engine) no codes are thrown.

Code notes:
To save on time, P0301, 303, and 305 are misfire detected on cylinders 1,3 and 5 respectively. P1316 and P1313 are both emissions related regarding excessive misfires and P0300 is a "random misfire detected".

I have also refilled the tank twice from 1/4 with to be sure this is not a gas-related problem.

I'm wondering what would cause this behavior. It doesn't seem reasonable that all three coils/plugs went bad at once. We also can see that the fuel pressure seemed good (I don't recall exact number but 54lbs sticks out?)... though I seem to only recall checking it at idle. Another point to make is that it doesn't happen 100% of the time, but if I'm slowly climbing in RPM (like on the highway), it will always happen.

The guys at the shop suggested that there could be a minor vacuum leak somewhere in the intake... if that were the case, though, I would expect that to effect me across the whole RPM band.


Sorry for the long post, but I really appreciate any help!

 

Hi, all. Though there have been no replies, I wanted to check in with everyone and let them know how things have gone.

The shop tested the coils and they indicated that all three "rear" (bank1) coils were ohming out. Of course, that was the first thing to replace. As the shop started removing the upper/lower intake bolts, they discovered that one of the bolts were spinning freely. Obviously this means that we have a vacuum leak on our hands. Because the lower intake houses the threading to secure these bolts, it had to be replaced. $2,300 later, the car is back in my hands and is still having the same issue (after replacing the coils, fuel injectors, fuel rail and pressure regulator).

So, for the verdict, right now the *only* thing that could possibly be wrong still is a vacuum leak. Since I had searched for the codes I received and came up empty, I wanted to point others who might land on this page to this helpful thread:
https://www.jaguarforums.com/forum/s...ad.php?t=23792

Tonight I will check for vacuum leaks myself and return the car to the shop as well for a "formal" diagnosis. I'll check back in with the members here in hopes of helping folks who stumble upon this thread.

Edit:
P.S.
The shop did confirm that the lower/upper intake seal was leaking by spraying the area with a cleaner they had which caused a noticeable change in engine RPM. In my unfortunate case, this is apparently not the ONLY vacuum leak.

 

SimonRage, Were you ever able to fix your problem? I am having the same issue? I am about to change out all 6 coil packs tomorrow but I feel I am probably wasting my money.

 

Where do we stand with the fix for this issue?????

 

SimonRage hasn't posted since Dec 2010, if you are having problems I'd suggest a new thread.

 

The brass thread barrel could have been expoxied back in, saving BIG bucks!

 

I'm having a similar issue as well. I will find out the verdict $$ tomorrow.

 

I am having the same problem with my 2005 xk8 with 4.2 l engine,same cylinders same codes same bank. Did you ever find the problem . I have checked for vacumn leaks replaced plugs coils and injectors

 

Had same issue a month ago, Same random missfire, Excess emission and had misfire on 3 random coils. I checked for vaccum leak, Changed my fueal rail and nuzzles but it turned out to be a weak Fuel Pump.

 

Wolfy27, you posted in the incorrect forum. Do your search for this issue in the XK forum as you have a different engine than in the X-Type. You have a 4.2 V8 and no X-Type versions have anything bigger than a 3.0 liter V6.

 

+1
Post the codes there, too.

 

Don't waste money at the mechanics!