Odd PCM behavior using Tech 2

[gmcman]

So I'm trying to diagnose a cpas issue on a 05 TB with the Tech 2, code shows P0014....but when I command the Tech 2 to increase or decrease phaser angle it gives an error..,(I don't recall the exact wording") something like "signal speed to low".

I can put the trans in gear, lightly touch the gas and the desired angle and actual change with each other. I also have intermittent stalling in gear but all else checks out..coils, plugs, TB etc.

If I have a bad ground somewhere, can I see that on the Tech 2? Will it show higher resistance in a ground and if so, what are the tricks to find this.

Very well could be the CPAS, but why can't I control it, but the PCM can?

 

[budwich]

when I command the Tech 2 to increase or decrease phaser angle it gives an error..,(I don't recall the exact wording") something like "signal speed to low".

not sure but I think that's an indication that your vehicle speed was not happening... were you trying to do this with a stopped vehicle?.... or that the rpm of the engine was too low.

 

[TJBaker57]

I see the diagnostic calls for running the engine at 1500 rpm before using the Tech 2 to ramp up the CPAS duty cycle. What rpm were you at when you get the error message?

P0014 — 2005 Chevrolet TrailBlazer 4WD L6-4.2L VIN S Service Manual | Operation CHARM

Detailed repair manual for the 2005 Chevrolet TrailBlazer 4WD L6-4.2L VIN S.

charm.li

 

[Mooseman]

I have been able to use the Tech 2 to change the cam angle at idle and it would work except when getting to the higher degrees, it would start stumbling and wanting to stall.

I also have intermittent stalling in gear

Yours could be sticking, either the CPAS or phaser, in the advanced position, when coming to a stop/idle and causing the stall, hence the P0014. If the CPAS is at fault, maybe the Tech 2 isn't able to control it.

 

[gmcman]

were you trying to do this with a stopped vehicle?.... or that the rpm of the engine was too low.

Yes, stopped, idle was 600-620 RPM

What rpm were you at when you get the error message?

Idle, as well as raised idle, between 6-800 RPM

I have been able to use the Tech 2 to change the cam angle at idle and it would work except when getting to the higher degrees, it would start stumbling and wanting to stall.

This is what I remember with mine, it would either stall or almost stall at full deflection.

 

[TJBaker57]

Just a reminder...

Cam Phaser Operation and Monitoring Other Stuff.

I was wondering if anyone has done any active monitoring of the cam phaser operation while monitoring other things in the system such as fuel trims, O2 sensors, etc. Interested in understanding any impacts changes in the exhaust output might have on the downstream results. Of course, I don't...

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