My 5.3L has been acting as it is misfiring. Took some time yesterday to route the plug wires correctly, as I dint not follow a diagram when I installed new ones.

That helped a bit. But it was still a bit rough accelerating. So while it was idling, I decided to pull 1 wire at a time.

Now here is the strange part. Whenever I pulled a wire on the B bank, the engine got rougher, and the tach fluctuated. But no wire pulled on the A bank made a differnce. Yet there was a strong spark at the cap - wire connection.

But the engine does not feel like it is only running on one bank. I have had the Marelli failure twice, and I know what that feels like.

Thoughts?

 

Try pullingA bank FI plugs and see what happens with that!?

 

Jay,

Long time.

Pulled injector connectors on the A bank.. Engine idle became erratic. So I replaced the new A bank primary lead with the old one. A lot of the misfiring went away.

Then I routed the plug wires according to the factory diagram.

Engine has never run so smooth. Lesson learned

 

Scott
Well found.
For the benefit of all, I just mention that it is often worthwhile starting a car in the dark when looking for these mysteries, as if the HT leads are arcing, it will show up.
What make of HT leads are you using? Sounds to me like a better quality set would be worthwhile.

 

Greg,

First thing I did was to check the wires after dark. No apparent arcing. The wires were from a repudable vendor that everyone here knows.

I have to believe it was interference from EMI due to routing.

 

​​​​​​Good show! More than once I have been completely amazed by how something as BIG and powerful as the v12 5.3 can be so sensitive to change and just one little thing being out of place. Like a gentle giant...

Then, and I have to say (humbly) that I am amazed that I can sense it,,, tell the difference. What a love affair.

I drove 400miles this past weekend. Some state highways with curves and trees,,, 97 degrees... I've gotten to know what kinds of conditions will bring the temp needle just under N, and then, just over. What a thing. Then, the way back, 74degrees and the cooool smooth ride, top down, smoking my pipe and waves to the admirers of the car... I'm just like - am I that guy? Where did he come from.

The XJS is my FAV,,, over the 928, over both XK8 and XKR - hands down! What a thing.

TGlad you're straight, Scott. Be well!

 

JJJ, Good for you!
So few V12 XJSs are running as they should - I mean suspension 100%, interior aircon and instruments 100%, steering 100%, drivetrain 100%, brakes 100%, engine sytems 100%, alignment dead on, exhaust hanging properly - but when they are dead right, the car is head and shoulders superior to any other Grand Tourer.
And, they incite no jealousy, only admiration and wistful "if only" feelings in others.

 

Hahaha... Jeeeeze, Greg!
Thanks for the reminderz...
There is a LIL bit of work to do on most evvvvvverything you mentioned, lol. But it's all good and so it goes...