I realize I may be a little obsessive when it comes to my car (probably not the only one on this forum), but I have two observations following my recent timing chain job. I replaced all components: tensioners, guides, chains.

I have driven about 700 miles since the work was done and the engine feels smooth and powerful. Now for the two observations/questions.

1) Gas mileage has dropped about 1 to 1.5 MPG. It could very well be due to the fact I feel safer driving it hard now that all the timing gear is metal, but I can't be sure.

2) There seems to be a noise (don't know how to describe it, maybe whirring? Maybe a very fast rattle that sounds smooth? Air sucking in?) that occurs only at highway speeds and only when putting a load on the engine. Accelerating, uphill climbs etc. It is NOT loud, and it goes away if I press REALLY hard on the engine. If I just bought the car I might think it was the sound of a Jaguar getting aggressive, but the sound wasn't there before I did the timing work and it didn't show up until about 200 miles after the job (this is the part that makes me obsessive). If the sound is normal then it doesn't bother me, but I have no frame of reference for what a Jaguar engine is supposed to sound like.

For number 2 above, I have theorized a clogged oil filter, noisy alternator or power steering pump (used stethoscope and no unusual sound at idle), detonation (no engine codes though), timing off from where I did the work (except that the engine runs better/smoother than before), exhaust leak, etc. etc. I spent about 4 hours trying to research threads with similar themes, but nothing really definitive. I was hoping someone on here who did their timing system would say "Hey, I had those same issues afterwards and XXXX was the explanation!"

Thanks for indulging me,
Jeff

 

Put the stethoscope on the fuel rails: maybe injectors. Then on the VVT. The belt tensioner; water pump?

Oh, yeah: check the torque on the plugs.