2007 Mazda 6 4cyl autmoatic 2.3 160 000 kms on it timing is off
 

Hi, I had my Mazda to my garage today and he wanted to use his new scanner so hooked it up and ran all the assorted scans and diagnostics posisble on it! Good news is everything was good except the timing is off. Going as low as 5.5 asnd as high as 9.5, sharp peaks and valleys, not very smooth. I really dont know what that means but he said it and we watched the timing line together and it was over and under the "green" zone...
The car has a timing chain which should be good for ever.
I have had the vehicle for a year, I do oil changes as required, no issues with the car.
Anyone have any idea what could cause the timing to be off and how to go about fixing it?
I read the service manual and it says to adjust valve clearance at 120,000 KM which we did not have done (didnt know we should)... could this be it or should we replace the chain?
Thanks for your help, Gary

It is variable timing (says that in engine!). I'm not sure what training he was talking about as I know nothing about cars. He said injectors firing to early and too late. I called mazda and they said replacing the chain on these card is almost unheard of. For $100 they will tell me exactly what the issue is...

Gary: My reply from yesterday does not show up. I only had some follow up questions. And you must have seen it.

Usually the injectors are being fired based on input by the cam and crank position sensors. These sensors would be the first thing I would check.

I don't know the particular testing procedures. Usually I start with disconnecting and reconnecting the harnesses and by looking for dirt and stuff that could interfere with the function.