Once or twice a year, my XK8 (90K miles) displays the orange motor icon and/or message that the motor has dropped to reduced power. The mechanic gets things working again, but another incident is around the corner.
Is there a fix I can point him to?

 

DrOrb, knowing what the codes are that you are getting, we might be able to help you out. But, without more information, we would be taking stabs in the dark as to what is happening with your car. It could be a simple vacuum leak that is causing your issues, it could be a fuel pressure issue. Could be a lot of things. This is where the engine codes (PXXXX - where XXXX is going to be 4 numbers most likely) will give us a good starting point as to what the computer thinks it is seeing.

 

^^^^ The check engine light is telling you there is a problem. The codes tell you where to start looking. You need an OBDII code reader to read the codes, then something to tell you what they mean. Of course, you can post them on here and get plenty of help. Definitely a good investment (OBDII - onboard diagnostics 2.0) reader for maintaining cars like these.

 

In earlier cars I'd point you right to the vacuum line connected to the throttle body. That was changed long b4 2006, but ?, maybe it'll help? Wth ez enough to check vacuum lines.

John

 

A photo or diagram of these vacuum lines might be of help to me in the future.

 

As I have the same XK8 with even more miles on it, check the plastic piping between the air filter and the throttle body at the bend. This is where it will crack, thus allowing unmetered air in. A quick fix is to use duct tape around the bend.
Get a OBDII reader or take to AutoZone or similar and get them to pull the codes out.

 

P, this is the hose I referred to. My motor mounts wore, engine moved (a lot), would disco this hose. All ok until cc tried to accelerate. Nothing happened, cc disabled, restricted performance on dash.

John

 

Another thing that would cause this is the TPS. The one on my car had an intermittent fault which would trigger the limp home mode. Only happened after 30 min or so of driving. I purchased a new throttle body including TPS, but then also purchased a replacement TPS...thought I would give it a try. After removing the throttle body, taking careful measurements of the TPS position on the old throttle body, I replaced with the new one, did the throttle body re-learn and have had no problems now for over a year.
The replacement TPS was the same manufacture as the original one.

So I have a new in the box throttle body sitting on a shelf....anyone want to purchase?

What does your mechanic do to get it running again?

 

Thank you for all the excellent info.

My wrench determined Cylinder #2 was misfiring and retrieved fault code and scanned for other codes.

He replaced Cylinder #2 ignition coil, cleared DTCs and road tested vehicle.

So far, so good. My fingers and toes are securely crossed...

Thanks again for all your help!
_______________________
DrOrb
2006 XK8 Convertible, Burgundy