Hi I have 2007 Jaguar XKR supercharged V8 4.2
I had what I thought was timing chain rattle on start up
so had fitted new chains and tensioners
however since it was done it has not cured the rattle and there is a Engine management sign
which when read is saying Cam shaft timing out
but the car seems to be running fine?
Jag / Ford 4.2 I set up my scope the same way whenever I am testing VCT systems regardless of the vehicle I’m working on. If using a four-channel scope, I connect channel A to the #1-cylinder ignition signal so I can quickly identify the four-stroke cycle, channel B to the crankshaft position sensor signal, channel C to the intake camshaft sensor signal and channel D to the exhaust camshaft sensor signal.Start the car and capture a waveform. It would be a serious mistake to decide to tear down a engine to replace a timing chain that you think is off because you compared a waveform you captured to an incorrectly captured waveform uploaded to the Internet by a tech not aware that the supposedly known good waveform he was posting had the cams moved 8 or 10 degrees from the base position. The best (known good) waveforms are the ones you capture yourself and you know exactly what the conditions were when you saved the waveform. VVT basic skill set.
When the new chains were installed, one or both were a tooth off. Could be that sprocket wear caused the original chains to jump, as well, and that was the problem all along.
Hi thanks for your comment If the sprockets are worn would not the chain tensioner be deigned to take up the slack By the way the car has full service history and mileage is 93000 As to perhaps jumped a tooth it appears to run smooth enough with power However I will discuss your comment with mechanic Instadentally I have made a point of standing next to other jaguars to listen on start up and have heard the same rattle There must be other jaguar owners who have same problem Thanks
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