Heya, (2001 xkr)


I seem to be noticing what id call diminishing performance syndrome. And its not in my head. It just seems the car is getting slower and slower. It starts fine, runs fine, shifts fine, passes emissions, and doesn't smoke. Plugs are relatively new. All 02 sensors are new


As far as modifications it has a custom intake tube, mina air divider, all muffler deletes with a high flow cross flow center resonator, upgraded IC pump and blue top solenoids in the transmission. It had ran fine in the past with these mods, actually very strong. I had noticed at times the performance would diminish in the past but I always thought it was heat soak. I'm really not concerned if its a rocket ship or not but if something up Id like to fix it before I add some more stuff to it. So I do have the SDD with mongoose however I haven't used it. I just made sure it installed properly and would run. You all have any ideas? Perhaps things to look for on the SDD? tests to run? It could be in my head but I don't think so!


Thanks

 

Check that your IC pump has not blown a fuse.

If anything, in this cold weather the car should seem peppier. You might want consider monitoring the water temperature in the intercooler loop. It should be just a few degrees over ambient.

Also see attached TSB:

 

The problem may be a simple one. Excess slack in the throttle cable. Below is a forum thread with some good photo's of the adjustment. When i did mine it was like getting a new engine.

https://www.jaguarforums.com/forum/x...appens-155562/

 

I had addressed slack last year. Seemed to have helped a bit at the time. It sa new performance water pump..Ill check fuses but didn't think it would mater much in this weather. Performance seems off even right after I start it. Generally in the winter it felt awfully quick. I was also wondering if it could be a secondary or primary fuel pump issue. Its very cold out.....But I can check the simple thins in life for now. Maybe try checking some temp data etc

 

You might consider checking your fuel trims, see if something is out of whack there? I wouldn't think it's a pump since they only come into play in specific cases but testing them is easy as well (pull relay or jumper)