A/C Torque Loss ?

[DrX]

Will this still work properly when MAFless (G0108 and G0109)? i.e. is it dependent on the MAF input?

I have a pronounced "clunk" every time the A/C clutch engages at idle ever since I disabled the MAF for AutoVE tuning. Could this be related?

[DrX]

Guess I will have to try re-enabling the MAF before going to the dealer for A/C warranty service. Won't look good if it is a result of the tune.

[Blacky]

Check the {B4354} A/C air ramp in, maybe try making it less agressive.

Also check the amont of air that is being added for {G0108} and {G0109} A/C torque loss. Maybe try making it a little less.

Also, if there is a large difference between the A/C and non-A/C idle airlfows then you may get a clunk. I get a noticable surge when I engage the A/C at low speed. But I have not tuned my idle and low speed cals since a cam upgrade.

Regards
Paul

[DrX]

Check the {B4354} A/C air ramp in, maybe try making it less agressive.

Also check the amont of air that is being added for {G0108} and {G0109} A/C torque loss. Maybe try making it a little less.

Also, if there is a large difference between the A/C and non-A/C idle airlfows then you may get a clunk. I get a noticable surge when I engage the A/C at low speed. But I have not tuned my idle and low speed cals since a cam upgrade.

Regards
Paul

Post seems to have disappeared. I'll try again.

I tried your suggestions. These tables were all at factory settings to start with. G0108 was all set to 0 and I didn't touch it. Tried decreasing and increasing the values in G0109 in steps with no effect on the "clunk". Same for the ramp-in rate.

I did notice that Mag had raised idle speed to 600(from 550) RPM. Tried setting that back to 550 also with no effect on the "clunk". Did hear a pronounced knock from bank 2 at 550 RPM though?? Used bidi to try various RPMs. Still no effect.

I observed that the momentary drop at A/C engagement is about 50 RPM. Whereas, on my Trailblazer with the same engine, it is only 20 RPM. So perhaps it is an A/C system issue.

Only thing left to try is replacing the 1 bar MAP sensor and the Mag tune before I bring it in to the dealer.