Failed emissions due to timing? Can it be?

Alan Cordeiro alancordeiro at
Thu Apr 8 07:02:17 EDT 2004


Not sure I understand where the five degrees could come from.

1)  The crankshaft pulley can only go on one way...not sure how
it could go off by five degrees.

2)  If the pulley were off five degrees somehow, you still end up aligning
the timing marks on the CAMSHAFT pully to the (rusty, almost invisible)
timing mark on the flywheel. The engine reads the flywheel teeth and
once-per-revolution pin, and uses this as the basis of timing.
therefore, if your timing check was good....the front crankshaft position
should not matter at all.


> I haven't experienced this first hand, but isn't it pretty common for
> the front pulley to slip out of alignment? I thought I've heard many
> people doing TB jobs and found the TDC reference had moved notably. It
> could be that yours has slipped 5°. Just a thought anyway.
> While improper timing can certainly give poorer emissions, you didn't
> mention if your car passed (or was tested yet). Could be your timing is
> fine with the pulley slipped, or it could be the ignition is being
> retarted by the ECU too. Perhaps it's falsely detecting knock?
> -- 
> Dan Cordon
> Mechanical Engineer - Engine Research Facility
> University of Idaho
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> 200q20v at

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