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Idle fluctuating - only with A/C on

 
Old 08-16-2017, 09:45 PM
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Default Idle fluctuating - only with A/C on

I just charged the A/C in the car (04 MSM, FMII) and now the idle fluctuates greatly, between 1000 to 2000 rpm, but only with the A/C on. It settles down to normal with the A/C off.

The AC Clutch Idle Speed Target is set to 200 across the board for all temperatures. Any ideas?

I am new to ECU tuning, and this car, and was reluctant to start changing settings without a little more guidance.
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Old 08-17-2017, 09:45 AM
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Originally Posted by stig'sbaldbrother View Post
I just charged the A/C in the car (04 MSM, FMII) and now the idle fluctuates greatly, between 1000 to 2000 rpm, but only with the A/C on. It settles down to normal with the A/C off.

The AC Clutch Idle Speed Target is set to 200 across the board for all temperatures. Any ideas?

I am new to ECU tuning, and this car, and was reluctant to start changing settings without a little more guidance.
I could be wrong, but I believe that under - Settings - Idle speed control settings you'd want to adjust the ISC P Term until the idle tracks smoothly. Or at least post up your settings and I can compare.
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Old 08-17-2017, 07:32 PM
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I tried adjusting both P and I-term to no avail. P-term went from 150 to 50, I-term from 20-10. It would return to normal idle while the ECU was applying the new value, but would start to oscillate again as soon as the A/C clutch engaged.

Another strange part is that two out of the ten or so times that I restarted the car, it didn't oscillate with the A/C on.


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Old 08-17-2017, 08:33 PM
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I'm not sure why the idle speed target jumps to 1500 RPM at about 4 seconds.

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Old 08-18-2017, 07:56 AM
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Same problem here. + My main problem is that the car cannot idle when I lift off the throttle. Just dies.

No problems with AC off.
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Old 08-19-2017, 08:55 PM
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Below are the settings in my own car. Occasionally, I'll get about 3 oscillations when coming to stop before the idle smooths out. I think the idle increase speed of 184 is still a little too high. I may try 150 next time I connect up to the Hydra.

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Old 08-23-2017, 08:55 PM
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Thanks Ken. I'll try those and see how it goes.

I'm assuming that you have more ISC control settings because you are in expert mode or something? Still haven't figured that part out.
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