V88 Idle Speed Control & AirCon step issues

[Guest |824|]

I am having a problem adjusting the idle for my 95 Audi S6 with V88 unit on 4.4.3 firmware. I have a 2 wire idle solenoid and it seems to respond to a 20 hz frequency setting using the test functions. I am using open loop setup.

Problem #1:

Adjustments in the idle speed control table are opposite what they should be, i.e., higher values (of duty cycle) decrease idle speed which is reverse of what the help files state for a solenoid setup. I am trying to fix a cold start stall issue. There also seems to be not much control/range in the adjustments here as well. I can change a value from 4 to 10 and have not much change in idle if any at all. I have zero'd out all idle-up tables per the tuning instructions and the min and max clamp settings are set to not interfere as well.

Problem #2:

I have not been able to get the AirCon step values to have any affect on idle control. I Digital Input #1 correctly wired to the factory Air Con Request signal from the car's factory A/C control unit and I do get the runtime value to show "on" when I turn on the AC with the car running but it will just stall the idle out, no increase in the idle. Perhaps this is related to the idle problem listed above? I simply increased the idle to about 1,500 rpm so that when the AC turns on the idle then drops to about 900/1000 for the time being.

I noticed in the tuning instructions it mentions that an Aux Output needs to be setup for the A/C clutch which I understand if you want to take advantage of the hard accel switch off function but I don't think it would be needed to use the basic AirCon idle up function unless I am wrong.

Thanks

[Simon]

Hi can you post your map on here and we can have a look at the settings.

The AC idle up is based of the aux output you could use a virtual aux if you dont have to switch the AC clutch.

[Guest |824|]

This zip file contains both the original tune and a copy of it that I have used to change the idle to be higher since the AC idle up control isn't working.

I have plenty of aux outputs open to be used so not sure why the virtual one would be needed.

thanks

Custum tune - RS2 base from Chris_06.11.11_apr modified.zip

[Simon]

Thanks for that.

Couple of things noticed. Duty cycle is very low some solenoids will start to open again at values under 30%

Suggest raising all values to 50% in the base duty cycle.

Frequency should be raised to 200-300 hz.

Suggest using a virtual aux as assumed you didn't have the need to switch the clutch in and out. So no actual output would be required.

Is this a Bosch solenoid?

[Guest |824|]

Thanks,

I'll try those changes. Shouldn't I be able to use the test features to check the proper frequency and control of the solenoid? Is there a way I could check the device itself with a multimeter across the terminals? Yes it is a Bosch part.

I looked up using the Virtual Aux ouput but am not sure exactly what it does. There is no choice to select ISC solenoid either. Any help on this? Am I to setup the AC Clutch setting here?

[rayhall]

Most idle valves operate in the 150hz to 300hz range. The bosch valve need to be as Simon said around 200 to 300hz. If you have it set too low you will not get correct control.

If you need to know the actually value, look at a Audi workshop manual, or use an oscilloscope to read the Hz on a standard car. It is not that critical as long as you are in the 200-300 range.

Virtual Aux outputs, are outputs that do not go to a physical pin on the ECU connector. They output to the ECU processor. This then can be used as a value to turn things on or off. You can stack up the Virtual Aux outputs so you can control something based on many parameters.

Ray.