My problem:
When is engine cold, I have only 500 RPM.
When warmed, I have stable 800 RPM.
But:
- AAV is working good, Open when cold, closed when warmed.
- supplmental air valve (I have 45 sec timer, US model) is working good, closed after 45 sec.
- temp sensor working good (growing to "N", when engine is warmed).
- TB butterflies are set to 0,05 mm both

I don´t know, where to begin to find why it is so.
Thanks Roman.

 

 

AAV :mouth" is closed too far.

Have a read of this, it explains how to "adjust" the Cold speed when rebuilding that AAV, and maybe someone has tapped it too low.

Timing may also be a tad retarded. 2nd attachment.

 

Thanks
Crackerbuzz:
I have 1988 XJS, H.E.P-EFI (Lucas). I think, that I have no cold start injectors. And I have CSR ? I think no.
Grant Francis:
AAV is one year old (was new) I will try clean it with WD40 or butterfly cleaner.
Timing (engine advancement ?) is set to 18° BTDC (3000 RPM) and I checked it with stroboscope. I think, that Your second attch was about it.

I am stunned, that I have no "startup reduction of RPM" (from cca 1100 to 800 RPM) when AAV slowly closes. I have 500 RPM after start and after 2-3 km when engine is warmer, 800 RPM. All RPM when "P" is set.

 

OK.

New can still be out of whack, law of V12.

Ensure the throttle bodies are CLEAN, as they do "goo up" with the standard V12 Goo. This blocks the disc air bleed, and can reek havoc.

Most of mine run at about 20+ deg, no timing plates, so not real sure, but definately more than 18. I never time one the old way, too scary, so "drive timing" is the best way to compensate for fuel, wear, age etc etc.

 

You don't. Jaguar stopped using them on the V12 around 1983 or so.


One alternative is to do nothing.

The higher idle when cold can be very easily duplicated, if desired, with your right foot pressing the throttle

I drove my previous V12 for years with an inoperative AAV. I removed the AAV entirely on my present V12. I have no issues dealing without high idle speed when cold, Start engine, drop transmission into gear, drive the car. Only when the weather gets near freezing does the engine complain.....but I just nurse the throttle for 30 seconds or so until the engine stabilizes and all's well after that.

Cheers
DD

 

Agreed Doug.

None of my V12 engines have that silly AAV, and been that way since about 1994ish.

Another thing that may be "hissy" is the mechanical advance network inside teh distributor, siezed in the retard position. Well documented and easily sorted.

 

Thanks.

Grant Francis :
I will check my butterflies. I suspect, that fuel portion does not respond air portion. (is higher). And thanks for "goo" I know new word, my English is from secondary school (40 years ago), But Oxford dictionary helped me
Vacuum advance is new and working under vakuum good. "Hissy" - next new word

Doug:
CSR - I thought.
AAV is working good, It is clear, I can replace AAV with foot, but I am "stickler ?" and want to know WHY it is not good
I must measure butterflies gap, Something tells me, that I have enough fuel but not air.
Cheers Roman

 

Roman
Good plan to check everything. Having said that if the tickover is OK when warm, I think that enough air is getting through the butterflies.
I still think, if there is a fault at all, that your AAV is not opening sufficiently when cold. How sure are you that it is absolutely all the way open?
Also, in principle, what is wrong with a steady 500 rpm when cold, if the engine does not stall? Not all AAVs are identical over the years, either, so it is possible you have a perfect AAV that only does give 500 rpm cold.
Good hunting anyway.
Greg

 

Thank You gentlemans.

Greg:
I inspected it with camera (cold, warm - full closed, full open).
Yes You have right. The engine is running good on 500 RPM, does not stall.
Maybe I am looking for a bug, where it is not. There are worse things in the world

 

I have replaced my AAV with a new one and adjusted it, mine will runn at around 500 to 525 when cold, but runs great with no sputter, like Greg said, the AVV can and are tricky buggers to get set exact.

 

Hi DOUGGY

As has been already said, there was a Service update, that recommended using a Stronger Spring, so it might be worth checking to see if its listed under a different Part Number (ptjs) will know

So fitting one of those Stronger Springs may well solve your problem for just a few $$

 

Also. Now that i know the us no warning for no oil given there is no dipstick and the undertray hid the fact i lost 5 qts of oil.....

how often are you all going thru the PITA oil level check in the dash

 

l have the same issue, is this the cold start relay?

https://xks.com/i-6919017-jaguar-luc...1-546-100.html

Cheers AOI