I've come across a potential issue and thought I'd ask the forum as I can't visibly see any issue to explain this...

I've been experimenting with various cleaning products over the past few years and thought I'd try the foaming Seafoam treatment for the intake manifolds. Given the issues with oil blowby they are quite dirty and seemed to benefit from having all that sludge broken up and sucked into the engine, car is abit smoother anyway. I used two hoses from the small crossover pipe into a T fitting and sprayed the solution in but I noticed the suction (vacuum) from the passenger side was pathetic while the driverside bank would pull the skin down from my finger if placed over any of the various holes once the plugs or vac line was removed. This was consistent even while turning the throttle by hand it just had more suction on the one side but I don't seem to have any performance issues that I know of while driving...should I be concerned?

I also think there is an injector(s) not keeping up on the passenger side but could that even effect the air flow that badly? I do have a refurb injector set to resolve that issue.

 

Normal. Don't be concerned.

Cheers
DD

 

Since things are performing wellI don't know if concerned is the correct word but curious for sure. I would expect vacuum to be in a similar range. I would understand the extra air valve might have an effect and the idle air valve being is on the drivers side might have some less restriction but I would think they would measure within an inch or 2 on the vacuum gauge.

 

sometimes the throttle valve plates are NOT adjusted properly/evenly, and can make a difference in air flow at idle mostly, as they open its not so noticable or trouble some! pic where my AAV was located , that is for my digital temp sensor is now!

check for worn or loose linkage pieces,ETC. and as said AAV can be annoying/sticky etc.( did away with mine and use the use TB plate adjusting screws), BUT then you need a cold idle air flow device!
Jaguar engineering was unusual at best! my opinion, but at that time most of the automobile industries were in a scramble to meet up coming emission systems,must have worked earth is still here,LOL.
ron

 

as a note when air flow at idle is uneven will have unbalanced exhaust temperatures ,side to side differences!

 

Do you have a write up on the AAV replacement? Mine is 4yrs old and is starting to get quirky, very odd high idle while cold, issue not present 6 months ago.

I'm tired of these junk after-thought add on components, that and the AC air valve all junk why cant the car manage its idle and air fuel ratio electronically?

A device fitted to another sensor input to impede or modify ohms reading maybe? I don't know I'm not an engineer.

 

Once upon a time I took my AAV off and tossed it in the bin.....and I've lived happily ever after


Cheers
DD

 

Later Jags caught up with the times and do have electric idle control. And even some of the older ones have an electrically heated AAV that almost never gives trouble.



Cheers
DD

 

As wrote Doug "Normal. Don't be concerned". Left side is stronger than right side (when idling). But when You measure vacuum in inlet manifold behind the butterflies, is approximate the same.

 

Vanc,, maybe you would be better off measuring and adjusting things for a matched exhaust temperatures ,side to side as close to the manifolds as possible not at the end of pipes, that and just off idle!

i check mine after a spirited run , while still hot , seems to work for me, of course thats who i want to satisfy,he is a fussy dude at best!

ron