The mechanic showed me a black cylindrical gadget with a site glass on it and a spinning disk behind the glass (engine running) with wires going to it. It is in the same place as the distributor would be, but my XJ6 is electronic ignition. Is that the camshaft sensor? I can't find it in any of my XJ6 manuals or drawings.

I never saw it before because it was covered with grease. Thought it was a motor mount.

Idles smooth, may run good for a few blocks, then stumbles, backfires, black smoke, no power, won't shift to 2nd gear, 5 mph, but idles smooth. This was happening after heavy rains and splashing puddles. When it dried out, ran OK. But now it doesn't run OK at all.

Mechanic has had it a week and may need help.

 

It is the camshaft sensor. If that gets off timing, the car will not start with the harness plugged in. Accidently messed with that when I did my upper timing chain tensioner and the car would only start after 3 seconds of cranking and the harness unplugged. Takes about an hour to bring it back into the correct timing but it involves removing all spark plugs and bringing the engine to TDC(top dead center) and looking at the position of the 4th cylinder cam position (It should be pointing upwards if I remember correctly)

Sounds like a sensor underneath the car is getting wet and shorting something out. I would try to look for any exposed wires underneath the car..

 

I know it is a tedious job of reading ALL the TSBs issued for this model range but there is so much info to help with diagnosis.

I uploaded related TSBs (along with HUNDREDS of others) in the large file area.

This might help or it could be something else.

good luck.

bob gauff

 

someone should send you money for all the info you post robert

 

Brutal
Jaguar did all the work publishing the info.
I just remember where to find it and offer it to others to read.
It saves time typing if the info is already a document.

Also kinda hard to put a coin box on the side of everyone's computer.

bob gauff

 

Just to add to AlbBolivar's post, the AJ16 Engine Control Module (ECM) refers to the camshaft position sensor (CMPS in X300 lingo) to establish initial ignition timing within 2/3 of one revolution. As soon as the engine starts, the ECM ignores the CMPS and refers only to the crankshaft position sensor (CKPS) for its timing reference. Without the CMPS signal, the ECM will use trial-and-error based on the CKPS signal until it discovers TDC for cylinder 1 on the compression stroke. This can take 30 seconds or so of cranking before the ECM figures out the correct timing. This info comes from the AJ16 Engine Management System Dealer Training Manual.

Sparkenzap disconnected his CMPS to see if his X300 would start, and it eventually did, but it took about 30 seconds of cranking.

Cheers,

Don