Good evening/morning all,
I have been troubleshooting a surging issue for more than 2 months without success. I have read and read and checked and re-checked everything that I know how to do. A little history; my parents purchased this beautiful vehicle when it was new and I recently acquired her. My dad was the expert and my go-to with any issues. I have been following Jaguar Forums for quite a while however just joined this evening b/c frankly, I just don't know what to do. I have looked over and replaced any vacuum lines that even appeared to be getting old. I have checked the air intake amounts on both sides with the original tool and they are as close as can be. I have almost equal vacuum pressure on both sides of the engine. What happens is that when I am driving and slow down below 2k RPM, the engine surges until the RPM drops below 1k. I remembered when watching my father work on the engine that the ECU had an air line that fed it information. I have made sure that the line is clear and even removed what appeared to be a filter for a couple hours to see if this helped. I also remembered that you could adjust the fuel mixture on the ECU so I tried richening it up and that helped a bit. I am now, looking at a couple items and would really appreciate some guidance. The distributor, rotor, wires and plugs have not been changed in quite a while. I've also, with the help of articles within this forum, noticed that the auxiliary air valve is about as far in as it can go. (cold idle screw) I haven't taken it off the motor to try the hot water test yet. With that said, the car also does not get a lot of road time. Just turned 77K on the ODO BUT would really like to fix this problem so I can drive it more often. Unfortunately I live in Northern VA and traffic can get horrible and the surging makes her not so much fun to drive. Any idea's from the incredible expertise that resides within this forum? Thanking you all in advance for your time and guidance. Such a gem shouldn't be sitting in my garage but I have learned that finding a Jaguar mechanic that knows this engine is very difficult to locate; a lesson I would have like to have skipped. R/S Patrick

 

As i mentioned in the New Members Area.

Here ya go..

If something is fuzzy, unclear, whatever, ask away.

AAV rebuild procedure.doc

Adjusting the ECU fuel pot.doc

HE Tune up.doc

I have more if these are unclear, and thousands of hours under the bonnet of various V12's over the years.

 

Are both throttle blades adjusted to the correct .002" clearance, and the linkages synchronized? And the throttle bodies cleaned?


Cheers
DD