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View Full Version : Automatic Camshaft Adjuster - how dooes it work ?


GrahamThompson
02-03-2011, 12:26 PM
I'm rebuilding my ADR cylinder head but slowly as I only get a few hours a week.

Out of interest how does the automatic camshaft adjuster connected to the chain tensioner work ? Does it sense the the gap in the tensioner and feed this to the ECU for the timing perhaps ?
GrahamThompson
02-03-2011, 04:51 PM
Thinking aloud since I posed the question...

The Hall sender at the front of the input camshaft must be used for the timing. So what does the automatic camshaft adjuster do ? It cannot be to report failure on the chain tensioner otherwise it would be a "sender" and not an "adjuster". I can see how it can measure the gap (i.e. tension) but how is it an "adjuster" ?

No doubt I'm probably overlooking something really obvious here. Please tell me. Thanks.
caldirun
02-03-2011, 09:58 PM
Thinking aloud since I posed the question...

The Hall sender at the front of the input camshaft must be used for the timing. So what does the automatic camshaft adjuster do ? It cannot be to report failure on the chain tensioner otherwise it would be a "sender" and not an "adjuster". I can see how it can measure the gap (i.e. tension) but how is it an "adjuster" ?

No doubt I'm probably overlooking something really obvious here. Please tell me. Thanks.
Would it measure chain stretch by its position and adjust the crank to cam offset figure?
martin1810
03-03-2011, 10:46 AM
It is for avariable valve timing. The engine ecu activates the solenoid which allows oil pressure to slightly rotate the inlet cam. This means the timing of opening and closing of the inlet valves can be altered according to engine speed.
elanman
08-03-2011, 01:57 PM
Some good utube pics of a working system on a Porsche9they developed it on a 944s2
GrahamThompson
08-03-2011, 03:04 PM
Thanks guys.
So the solenoid, inside the spring in the tensioner is moved to allow/restrict the oil flow into the tensioner. This allows the VVT at engine load / speed.
Wow that's clever - I wondered why the engine design had a chain driven inlet cam rather than by an extension of the cambelt. Now I know
Thanks again.