I suppose we all have had one of these "what am I dealing with" thread at one point or another, and at last, here goes mine.

After addressing one thing after another, I have my 2000 xjr nearly all buttoned up, and was preparing to go price out some winter tires on newly aquired 16" xj8 wheels. Well, on the drive to the tire shop, coming to a stop the car began to accelerate as if being given gas. I quickly pulled over to begin to diagnosis the problem, as I noticed a high idle upon stopping. I shut it down, let it cool down and rest for a moment, turn it over and acted perfectly normal. Being close to home and sti having a good ways to the tire shop I decided to turn around and just drive it home. After just driving it just a few blocks, surely enough, the failsafe mode light comes on.

I've been familiar with said light as I've had throttle body positioning sensor issues before but after having updated and replaced the connections, all has been smooth sailing since. Weirdly though, driving it in failsafe mode, I still had ample throttle and was was able to cruise home at 20mph, as opposed to the 7 or 8 that the failsafe mode normally restricts the car too. Nevertheless I head home thinking I'll grab the codes and look it up and address the problem, but before doing so, mere blocks from home the light defeats itself and drives quite normally. Weird I though. I'll take a look at it a little bit later.

Well, went out later perhaps an hour and half and go to start and immediately upon doing so, she revs to 2600-3000 rpms and hangs there for about 30-40 seconds. It eventually calmed down to 700rpms, to which I shut it down. Then turned the key, and while performing the system check I hear a loud repetitive click near or within the throttle body that will click until I crank the motor or turn the car off. Upon starting it again it repeats the prior process, straight to 3 grand, hangs and then evens out.

Most peculiar of all, and ultimately my cry for help, the failsafe engine mode has since gone away, and no codes have produced themselve despite the strange engine behavior. I have gone over the lines looked for a vaccum leak but to no avail, clean the connections to the throttle body which has provided no change, so I turn to you guys.

Any ideas or thoughts?!
Thanks in advance for your help guys!

Edit- So having opened it up, the butterfly for the throttle body is what is causing the ticking as it continues to flutter. Any idea as to why it would promote such activity? Last time I had throttle body woes it gave me the p0121 code, but this time around, nothing hence the head scratching......

 

Sounds exactly like you are seeing multiple ECM resets because the observed behaviour is what happens after a reset.

That points at a weak battery or other electrical problem that is inducing the resets.

For future posts, please use more whitespace. It is free and makes the post much easier to read.

 

So a little update, and possible problem located.

The car continues to cold start into a high idle but eventually she smoothes out and power delivery is rather effortless and smooth once the engine temp gauge gets halfway and all warmed up. The idle at times fluctuates very slightly but just enough to be noticeable.

No codes or check engine light has been thrown, so it is all a search in the dark.

I immediately assumed throttle body, having issues in the past, thus the connections were cleaned up and secured, but no change in the cold starts. but no codes have been thrown despite the engines activity.

After looking over the engine bay for a good hour I came across what appears to be a leak in the plumbing for the egr. There seemingly was a prior patched up repair, but is no longer holding. Can someone confirm what part this is, and if anyone has any info on such a repair/replacement, that would be greatly appreciated.


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You may have a leak -- but if you are pointing to the foil as if it is a fix for something .. it is not.

That came from the factory - I believe a bit of a heat shield for the cable above it.

 

Wrong, that is the EGR pipe, and it is a flex pipe that is subject to leaking. Replacing it is difficult without removing the Throttle body.

Also be aware that it is not uncommon to find the bolts securing the EGR valve to the manifold missing or loose. I just reppaired a XKR with that problem.

 

Indeed it is the egr transfer pipe. Did you ultimately replace the pipe or were able to patch it and or seal it?

 

I did not have to replace it, the EGR valve was my target. But I would not try to repair, it's rather thin.