View Full Version : A/C Torque Loss ?
DrX
November 12th, 2005, 02:47 PM
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
November 18th, 2005, 08:22 AM
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
November 18th, 2005, 10:54 AM
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
November 19th, 2005, 04:20 AM
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.
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