After warm-up, engine has terrible idle as though asking for more fuel or more air. see below

XJ-S
1

While this rough idle is going on all I have to do is press fuel pedal and smooth engine responds.
I set those butterfly valves at .005 as directed by Kirby book…now I have been told .002 is more advised…
Please help me out…I’m getting a little confused…
Thanks,
Sloth

2

You should follow the Book’s advise, everything Kirby states is crosschecked and verified.
The point of the .005 gap is so that the butterflies don’t jam at the throttle body and the most important is that they are exactly the same both sides.

On your other post you say that your coolant level was bellow the CTS.
If this is the case the CTS’s reading is completely false and thus the ECU can’t fuel the engine correctly.
The engine would work fine when cold but not when it goes up to temp.

Aristides

3

Thank you Aristides
My cts is doing it’s job after 5 min. Warm-up cases and it goes into a very lumpy dance. All I have to is touch throttle and smooth engine responds. Remove foot and returns to lumpy idle.
Something at low rpms is causing this problem.

Thanks

4

What does a spark plug look like? When I had similar issue and looked, they were black with soot which told me I was running extremely rich.

5

Check your TPS (throttle position sensor / potentiometer)
If not adjusted correctly your ECU doesn’t know you are on idle.
All info at Kirby’s book.

Aristides

6

It could also be, as Greg said, you “Base” fuel adjustment at the ECU.