Hello gang,

I’m driving a 92 XJS 4.0L coupe. When I start the car, it idles like a diesel tractor for maybe 10 seconds then usually evens out. Then, when I’m at highway speed I feel a kind of ‘thumping’ like a hesitation. It only happens at light to medium throttle. Foot off the throttle it goes away and on harder throttle use it goes away as well. It all seems to happen around 2000rpm at 100km/h. Figure its the Throttle position sensor?

Any help would be awesome. Thank you!

Solo out..

 

Since there have been no suggestions, here is my 2 cents worth.

The XJ40 Group know this engine inside out, so I reckon more will answer from there.

Just like the Series, and XJ40 V12 People come into the XJS Section, as that is where the V12 knowledge mainly lives.

My 3.6 never gave issues, albeit an XJ40, it just did what it did without fuss, still does.

 

Thanks Grant!

I’ll look into the XJ40 group.