Camshaft pos. sensor CMP and fuel timing

[MarPac]

I was solving fuel timing problems during last year on my 95 3.0 Windstar.
Idle was unstable, but not so bad. Engine shaking when light acceleration below 2000RPM. Engine power was OK.

My Win is running LPG liquid gas, the situation was worse when driving LPG.

Using a diagnostic tool I found rich bank 2 while lean bank 1 when IDLE. The long trim for bank 1 +15%, bank 2 had -13%. It seemed like nr. 4 cyl. eats fuel prepared for nr. 1 cyl. Strange situation. There is a vacuum pipe feeding brake system by vacuum connected to cyl. 1 intake manifold so the air coming out from such pipe sucked part of the prepared fuel for nr. 1 cyl.

And there is the problem, spark is determined by the crankshaft position sensor while fuel delivery is triggered by camshaft pos. sensor. When this CMP sensor is miss-aligned, the fuel is prepared in front of intake valve too early (late). Engine keeps running, because the fuel can "wait" in front of the intake valve until it's opened and air with fuel sucked into the cylinder. But while the fuel is waiting, it can be partly sucked out by another cylinder, especially in the nr. 1 cyl. and vacuum connection case.

Be sure your CMP is correctly placed. There is a correct method with a tool which comes with a new CMP but what to do if you do not have one or you want to be sure?

The following steps are for 95-99 Hall Efect CMP sensors, those with 3 wires:

1) Take multimeter and connect - rod to batery -, + rod to CMP's middle wire.
2) CMP middle wire is an output from the sensor. There is 12V when metal "moon" is between magnet and Hall sensor inside of the CMP
3) Rotate engine 60 degrees before Nr. 1 cyl. TDC. This position is detected by missing tooth on the crankshaft pulley. The first tooth after missing one should be under crankshaft sensor.
4) be sure you are before Nr. 1 cyl. TDC, not the Nr. 5 cyl. TDC!!! You can check this by putting the Nr. 1 spark plug out. The Air must blow out of the cyl. when going to TDC.
5) Now rotate engine clockwise by 8 teeth. This position is 20 degrees after Nr. 1 cyl TDC. In this position of crankshaft, the CMP's output must come up to 12V.

The TSB says that correct CMP timing is between 7th and 10th tooth after missing one when Nr. 1 cyl. is in TDC. It meens 10 to 40 degrees after Nr.1 cyl. TDC. Each tooth means 10 degrees, missing one is 60 degrees before Nr.1 or Nr. 5 cyl. TDC.

In my case, the CMP was well placed but 360 degrees out detecting Nr. 5 cyl :-(

Now the engine is fine and works great. I did this procedure after changing spark plugs, cables, oxygen sensors, catalytic converters ... Someone has played with the CMP before :-(

[MarPac]

here is a TSB diagram for this operation I found on web. It is not necessary to use scope :-)