After reading lots of information on the forum and contemplating different methods of activating the cold engine start procedure, I thought to myself Mmmm there must be a better way. Then I thought about the operation of the AAV and realized how good a design it was and if I was to invent a system it would be similar to the factory AAV.

So... I just purchased a genuine Lucas replacement from Engel Imports in Michigan.

Much easier. Jaguar engineers must have been good, otherwise we wouldn't be driving cars 40 years later!

Admittedly it was expensive in $NZD but you get what you pay for. ($341.00 USD)

 

Good for you !

Sometimes reinventing the wheel isn't the best use of time and effort. But, for many, the journey is as much fun as the destination. Nothing wrong with that.

As for AAVs, well, mine went into the trash bin ages ago. I had grand plans for a 'better' replacement but I'm over it now. The car runs fine without it

Cheers
DD

 

Doug... Good point!

How do you get it to idle if you have no AAV?

 

I don't know if it's toooooo late but I been eying this one for a while now. Shipping might be a bear but it might come in well under what you paid. Jus say'n

https://rover.ebay.com/rover/0/0/0?m...2F191747156590

 

Easy mod. I added a nipple to the balance tube and ran a hose from the LH air cleaner housing to the balance tube....with a gate valve to adjust idle speed.

A small nipple added to the LH air cleaner housing provides a bit of draw for the distributor vent system.

Or, a person could just tweak the throttle butterflies a bit.... so long as adjustments were equal on each side. But you wouldn't want the butterflies to get too far ahead of the TPS.

My hat's off to anyone sticking with the AAV. On both my V12s the AAV was dead when I bought the cars. I rebuilt both; both worked for some period of time.....then died again. I decided to wash my hands of them !

Cheers
DD

 

Very interested in the hand warshing...

Maybe I will wanna see you nipples,,, down the line,,, haha

 

 

In my experience, not necessary until/unless you approach freezing ambient conditions. Then you just use your right foot as the AAV for 15 seconds or so.

I should mention, though, that I have my base idle set a bit higher than spec, though, so that helps.

I'm not advocating removal of the AAV.....especially a functional one, when and where they exist . But, if you decide to just throw in the towel, the lack of high idle when cold really isn't an issue.

Cheers
DD

 

Thanks JayJag...

My one is a different part number as there are 2 or 3 distinct models depending on year. Not sure of the actual differences but maybe port depths or temp differences.

Mine needs the 4438 version.
Cheers

 

Yeah was going to do that but couldn't find a thermal switch easy enough.

 

Interesting you say 15 seconds or so. I need around 3 minutes before she idles by herself and thats no good for me as it annoys me!

I will see how long a genuine AAV lasts from new, that will be the test. If it fails early I will go the solenoid route.

Cheers

 

Three minutes would make me nuts.

I wonder if you're getting enough mixture enrichment when cold?

Cheers
DD

 

I am paying attention to this!!! I have never liked the AAV... Thanks to awesome advice of Grant Francis, I cracked open my malfunctioning AAV fixed and resealed... Still, on a hot day, the amount of time (and fuel) used on startup is a PITA. Is it possible to have something simple rigged,,, just on the days ya think ya might need it?

In the future Doug, I may reach out to see if I can get specifics on your fix.

 

I think my enrichment device may have been disabled. Whereabouts do I find the system for enrichment? Is this the 15 minute timer thing?

CHeers

 

Did you mean to say "cold day" ?

In warm weather the engine shouldn't need very much enrichment and/or much increased idle speed. And, once the engine is warmed up it shouldn't need any of either.

The AAV remains slightly open, even on a fully warmed engine. This, plus the .002" throttle opening....the specified 'base' setting.....gives you your warm idle speed. If you bypassed the AAV the engine should idle at about 400 RPM or so. The AAV remaining slightly open gives the extra 200-300 RPM plus the ability to make up/down idle speed adjustments.

If your idle speed won't come to 400 rpm or so with the AAV sealed off, you have extra air coming in from....somewhere. Or, a mechanical issue with the linkage or some such.

Three minutes of warming up before the engine behaves, or ".....the amount of time (and fuel) used on startup is a PITA" suggest, to my ears, that something foul is afoot that goes beyond the AAV.

Cheers
DD

 

Cold enrichment is dictated by the CTS---Coolant Temp Sensor. It gives a temp reading to the ECU. On a cold engine, as reported by the CTS, the ECU will hold the injectors open longer to give a richer mixture for cold starting and cold running. These sensors often go wonky. In fact, mine is on the blink and I'll be replacing it soon.

(Until 1984 or so the V12s had a cold start injector system. This stand-alone system, using two separate, dedicated injectors to squirt raw fuel into the intake, was problematic. Many were intentionally disabled; Jaguar stopped installing them)

Cheers
DD

 

Mine is the later model. Doesn't have the separate injectors.

OK things making sense now.

Doug can you please tell me where the CTS is located?

 

I think I know that my AAV is goneburgers...

When the engine is cold and I remove the AAV idle adjustment bolt completely she pulls in heaps of air and runs up to about 1800 RPM

As soon as the bolt is back in one thread the engine stalls!

I guess this means a jammed AAV piston

 

Immediately aft of the LH thermostat. Item #9 in this illustration

https://www.jaguarclassicparts.com/u...e-lh-5-3-litre

Can be checked with an ohm meter. I have specs if needed. Or, aftermarket replacements are so inexpensive ...$20 or so....many just replace 'em.

Cheers
DD

 

Brilliant cheers mate.

Just ordered one.

Thanks