I'm trying to diagnose the throttle body condition , I have it off the car, how can I test it?.....specifics;

I have a 1999 S type 3.0 , so an early model.
After changing the spark plugs , ignition coils , upper and lower intake manifold gaskets , cleaning the fuel injectors , which required the removal of the throttle body , after reinstalling it all , the car gives "fail safe mode" on the dash and wont start.

Once ignition is turned on, before cranking , the throttle body makes a very loud continuous buzzing sound. This doesn't stop until 2 or 3 seconds after the ignition is turned off.. But if I press the accelerator pedal , the buzzing from the throttle body stops..
I removed the trunking and noticed the throttle body butterfly dosnt move at all in all this.
I understand it should move to "idle" position with ignition on , say 5 degrees open or so.
The car will crank if the key is turned , but obviously won't start .

Should the butterfly open if pushed with fingers now that it's outside of the car on the S type 3.0?

I'm thinking it may be stuck from cleaning it, with some residue gunk and that's causing the buzzing of the throttle body as it trys to open up idle. That in turn is giving the fail safe mode error.
My OBD2 scanner says no fault off exist.

Regards
Peter

 

I would NOT stick my fingers into the TB with it connected to the harness. (plugged in)
The motor is quit powerful and won't let go even if you yell at while it severs your finger!
You might try to open the throttle blade with a wood dowel?

 

The throttle body is out of the car and not connected, should the butterfly be able to move in this situation by being pushed with the fingers?
I'm trying to determine if the butterfly has binded or is stuck somehow , and hence that is giving the buzzing problems as the fail safe error on the dash.

Peter

 

Got a couple of spares in my Pile-O-Parts. Sure enough, they would open when pushed against moderate spring pressure.

One caveat: When closed, the plate is not at 90 degrees to the bore. Maybe 80 degrees? If pushed on the wrong side of center, the plate wedges tighter and won’t move. It only rotates open in one direction.

 

Kr98664, thanks for checking on your spare parts....is that one that you looked at a throttle body from an S type ? ...or from another model Jag ?

I concur, the butterfly lays at 80 degrees or so.
I'm going to clean this again , but it's not really dirty, with some stronger throttle body cleaner and see if it opens.
If it opens, I think it will all work and the fail safe message on the dash will disappear.

Peter

 

Both are from an early model V6 S-Type.

One is the original unit from my ‘02. It was intermittently throwing some code. I’d have to dig through my notes for the details. About ten years ago, I replaced it with a used unit from eBay, with no further issues.

The second unit is an untested used spare I picked up, also from eBay, as insurance.

 

Be careful of the coating and indeed the whole item as it's a precision part. Does not normally need messing with...

 

The throttles are ALMOST the same for the V6 and V8. Just the water pipe on one of them.
I don't remember what one but I think I did install a V6 TB on a V8 and just ignored the coolant pipe?
Been a few years ago so no exact memory.