So, pretty sure I figured out why the car was hesitating/nearly stalling when i tapped on the gas.

I have no idea what any of these parts are called, and i'm still learning how a car functions but...
So... there is a little wheel that travels with the throttle body, and that wheel is attached to a sensor of some sort. My guess is that sensor indicates to the ECU the position of the throttle body, and hence how much gas to give the cylinders. Anyone know what that little wheel and sensor is called?

NOW, the throttle bottle is mechanically linked to the air intake. It looks like as the throttle body opens, it opens a valve at the end of the air..uh... box thing that allows air into the engine.
So. I was fiddling with the throttle body while the car was idling, just tapping it open a bit. And the car would stall eventually.
I noticed that there was a piece missing on the linkage, looks like there should be a rubber gromit thingy there:




So basically the throttle body was traveling, but due to the missing thingy, the air thing wasn't opening at all! So it was giving her gas but no air.... hence why it was stalling when i tapped the gas.

What is this... what is this feeling that i now have? I feel.... good.... like... maybe I figured something out...
This feeling is powerful, almost... addictive...

Wait, is it called a:

THROTTLE LINKAGE MOUNTING PLATE BUSHING
??

 

i made two of them from ALUMINUM nice tight fit , no slop!
works great been 27yrs now!

 

You're exactly right! Because that round throttle cap,,, thing sitting in the center back of the engine works with a potentiometer underneath it - it sends a signal to the ECU for fueling - the wheel/disc moves a BUNCH before the butterfly disks in the throttle body open and allow air into the mix. The ECU dumps a bunch O fuel into the cylinders and there is no additional air to burn/ignite it... The throttle linkage (although it don't seem like much) is very sloppy with those bushings missing. I was just looking at mine today...

That and,,, looks like over the winter a mouse or maybe a NYC RAT decided to make a snack out of two of my HT spark plug wires over the winter... Jeeeeeze Louise!

Is an inexpensive fix - that fixes a LOT with the day to day running of the car. GREAT catch!


​​​​​​​

 

Accidentally posted this to a different thread anyway:

Does this thing have O2 sensors? I cant remember if that was forced into the market that year. Also chances are your injectors themselves have earwax in the basket filter causing issues. Mine gained 12% fuel flow and an mpg jump from an injector overhaul. Same with my car's O2 sensors (again not sure about yours as its an 87) but improper o2 input will cause issues in my case it was overfueling alot and nearly stalling on initial acceleration.

Yours looks to have all the original vac hose tapestry to...I wont get into it now but nearly all those god forsaken vac systems can be ripped out and simplified. Thats another day.

As said above these are brutally simple cars, yours looks absolutely excellent. Looks like a new AC compressor to? Lucky.

 

Well done. Read Grant's sticky on setting up the throttle linkage correctly. And setting up the Throttle Position Sensor (the potentiometer thing under the throttle capstan.
Also, it is worth downloading and reading Kirby Palm's book about the XJS from Jaglovers. It is an excellent grounding about how the entire car works.

 

Darth
I have some new bushings you can have when you drop over.
Rob

 

Awesome Rob, it will be great to meet, work has been a bit crazy