AC Idle bump

[Cynical 1]

hate to bump up an old thread - but does anyone have a difinitive answer yet as to the work around of the plug and idle?

[evandael]

i posted this in another thread, but i think it'll be better here..

my thinking is that on the e30, the a/c compressor 'on' signal comes from the c211 connector, which goes straight to the DME:




whereas on the e36, the DME receives an input from the pressure switch through x20pin5, which then goes to the ecu.




so i assume it would be correct to run the lead from c211 to an unused pin on the body-side c101, which will then correspond with the e36's x20pin5. if you're repinning the x20 wires into the c101 connector, it's just a matter of lining up pin-to-pin.

Note: 93 325 M50B25TU to an 88 E30 325is

...

Tim

hi uncle tim! eric here.

[88E30M50]

Note: 93 325 M50B25TU to an 88 E30 325is

When the idle bump signal is passed back to the ECU, doesn't it go through X20 pin 5 (bk/gy) on the E36? On the E30, the low pressure signal comes from a black/red wire on the low pressure switch, around the front of the engine and down the left side harness into the C204 connector, then over to the C136 and on to the ECU at pin 40.

I'm thinking that cutting the Bk/Rd wire near the firewall and then running it through an unused C101 pin, then into the X20 pin 5 should do it. Does that sound plausable?

Tim

[328ijunkie]

^ Doesnt work that way.
Im still investigating. Basically that bk/gray wire runs from climate control unit. Through Pressure switches back to ECU to tell the ECU its okay to fire the compressor.

[325e10]

E36 compressor requires PAG46 oil, the PAG oil is glycol based and will dilute with 134a and when the system is emptied some of the oil will be gone too. Probably low on oil.

if you used ester oil the compressor will not last more than 2 years



That is because the 413 ecu needs a signal from A/C pressure switch that is located on the filter dryer, at pin 65. The way that you have is, the ECU knows that you turn on the A/C system but it will not activate it's "IDLE UP" unless it knows that system is full. The ecu controls the compressor on E36.

Could this be the case for me? I'm running OBD2 so non 413 ecu, so you're saying I need to run a wire from the low pressure switch to the violet / gray and it should trigger the idle bump?

[DesertBMW]

not possible to get to work. E36 climate computer sends coded signal to DME to turn on the compressor and bump the idle. Not possible to get it working on E30.

[325e10]

Did you try forcing 12v to the ecu wire btw? Forgot to ask

the wire from the switch is confirmed 12v, the compressor sounds weird and seems to be putting too much load on the motor though.

[328ijunkie]

Did you try forcing 12v to the ecu wire btw? Forgot to ask

[Gooch]

Bump. I'm interested also before I finalize my wiring.

[325e10]

I saw a thread on this but nobody seemed to have a definitive answer in it. I have hooked the violet wire from the AC Switch (switched 12v) to the Violet/grey wire on the DME harness. Yet Idle does not change when the button is pressed. I have an early model car 3/1985 and the motor set up is a M52 , obd2. Anyone else with this setup have their idle bump working?