tapping coming from engine.

[mut]

i have an 88 325i touring.when i bought the car on the drive home it started to make a tapping sound from the top end.i stripped the head and found the rockers,shafts and cam were worn so replaced everything in the head with genuine parts so its like new.i got it started but the tapping is still there,mainly on acceleration and deceleration,at idle its quiet.the only thing i have to do is get my service lights turned off this week.a friend said the ecu might change the timing as a way off me getting it serviced,is this true?any ideas of what this could be would be much appreciated.thanks,mat.

[Brianmoooore]

Ignore your friend!
M20 tapping is tappet clearance, noisy injectors or an exhaust manifold leak, and I did come across one once that had the head recently changed that had been excessively skimmed, and the pistons were kissing the head.
Rev it up and switch off the ignition. Does the tapping stop instantly or decay as the engine dies?

[mrb27]

i just adjusted my tappets because it was a bit tappy but turned out to be a exhaust manifold leak.. i have a snapped stud on there which i need to sort too

[Moffett76]

Also, if none of the above are the case, do check the spray bar if you didn't renew it during your top end build. Mine was loose at the bulkhead and caused the rocker lobes to wear down past adjusting.