Since I got the car it has always done this. Not real bad but seems worse at times.
While driving at cruising speed if I am just barely on the gas it feels like the car is surging, pulsing a little. If I get on the gas just a tiny bit I can still feel it until I get on it a little harder then I don't feel it. It feels like the throttle is pulsating, surging ever so slightly.
What is this?

 

Maybe the throttle cable is sticking, or something else that cable controls downstream with the air/fuel. I'm not that good with motors, but I would rule that out first.

Dave

 

Hi brgjag;
You are a Senior Member, so I'm sure that you've already pulled the codes to address this... but mine did this for awhile, and was cured by a new Throttlebody".
I hope it's something simple
Take care
Fred

 

Why would I pull codes??? I am getting no messages from the system. No check lights or performance warnings. It is not a cabke stuck or anything. It does it at cruising speed, say I am holding 55 I can feel an ever so slight surge as if someone is just in the slightest is messing with the throttle to make the car surge. It does not speed up it is jsut not a smooth run. Hard to explain.

 

First guess is the 'drive by wire' throttle motor is bumping up/down. Cleaned TB connectors? Suspect something in the electrical rpm sensor to ECM to TB motor.

 

Mine does the same thing. I understand it is the throttle body that needs cleaning. I haven't gotten 'round to it as it's a nuisance more than a problem. When I'm coming down hill I will get a yellow engine fail light flash at me just briefly. No codes stay stored.

Search for cleaning the throttle body instructions; IIRC come from Gus or Jag Tech. Tooth brush and can of carb cleaner.

 

we have a DIY file with some pictures in our FAQ thread at the top of the XK8/R forum, for that very item.

 

My 2003 did the same thing. I just fixed it courtesy of the throttle cable adjustment post you will find on this forum. give it a checkout and I bet it works.

 

Sorry Sir!!...I wasn't tryin' to step on yer toes...;.((( I had no engine light either, but it showed up at my Jag Indies shop (he's got a big butter n' egg boy's code puller). I'll jest trapse on 'round th' corner n' watch you fellers sift it out. I'll be using my good eye...
Faint Hearted Freddie

 

These are things I can do? Where are these located, look ike? Pics??

I have cleaned the TB once, just with spray, no tooth brush. Sprayed the MAP or what ever it is called on the car also.

 

There is a throttle body cleaner, different from carburetor cleaner. A tooth brush is not needed but a clean rag is. Clean around the hinges of the valve and the edges of the valve and the TB surface they mate to.

The throttle body connectors are electrical connectors connected to the throttle body. Carefully remove them, spray with a dielectric spray and reconnect.