AC Idle bump

[Sh3rpak!ng]

would love to know this... it's the last part of the wiring puzzle for me

[mpowerful]

I made it through an entire summer in new orleans without an idle bump and didnt have any stalling issues. I just dont see that it is that necessary.

[328ijunkie]

So ideally:
Ground to pin 16 of ECU (BK/Gray)
+12 to 19 of ECU(Vi/Gray)
When you fire the AC switch

This will fire the idle bump.

[emmanuel.dlc]

So ideally:
Ground to pin 16 of ECU (BK/Gray)
+12 to 19 of ECU(Vi/Gray)
When you fire the AC switch

This will fire the idle bump.

i will try this, i only provided the 12v to the pin 19 and obviously didnt do anything.

[keada714]

Did this work for you?

[abie199]

Hi,

Greeting from Jakarta - Indonesia, where the weather is hot as hell sometimes :D

Having an aircon in here is a must, especially when you are stuck in traffic. So here's what I've done. Instead playing with ECU harness, I decided to do it from the X20 - C101 adapter. What you need are pin #4, #5, and #6 from X20 connector (which most people say is not "used").

I made below diagram to help you understand how I wired this.



1. For AC switch, I 'tap' the wiring near the fuse box. You can use directly from the AC switch, or find it elsewhere which suit your build. Basically, it should give 12v whenever your press the AC switch button.
2. For the relay, you might need to adjust the relay's pin depends on the relay type.

I've done this in my swap project with DME 413 and Siemens 5wk9.

However, PLEASE DO IT WITH YOUR OWN RISK!

If you are success (like I did), your idle will bump when you start the aircon. And when you suddenly floor the throttle, the aircon will be cut-off for a while (2-3 seconds).
Of course you can improvise the wiring to add pressure switch, another relay to control pin #5 to contact ground only when you press the AC switch, and blablabla...

rgds,
abie

[Sh3rpak!ng]

So ideally:
Ground to pin 16 of ECU (BK/Gray)
+12 to 19 of ECU(Vi/Gray)
When you fire the AC switch

This will fire the idle bump.

is it really that simple?

bumping for summer time and curious if anyone has made progress? I'm ordering my AC components today. I'll post up here after I finish wiring with my results.

[mpowerful]

When i first did my swap i had this issue but its been 14 months and really it hasnt been any problem at all. In the beggining i got some stalling but it seems if you reset the ecu it will do this. Usually for first 15 miles then no issues at all. My a/c is kicking ice cubes with 95 ambients and not even a hint of a stall.

[MC Hammered]

Here is an update and a bunch of test results

Thanks for this detailed reply from pandaboo911 I was finally able to understand the missing piece of the puzzle. You need to ground the AC activation pin the same time you turn the compressor on so the DME does the idle bump.

http://www.r3vlimited.com/board/showpost.php?p=4610626&postcount=327

My DME is a MS41.1
AC activation input is black/grey and is pin 16
AC compressor turn on input is violet/grey and pin 19

Testing results:

1) +12v to pin 19, nothing connected to pin 16. This is where most of us are stuck. We get AC but when we get to a stoplight the idle hunts, rpms drops and we may get some shaking happening. So no idle bump.

2) nothing to pin 19, ground to pin 16. My standard idle is 850rpm, with pin 16 grounded the idle is around 930rpm. Remove the ground and the rpms drop to 850rpm. HOWEVER, if you permanetly ground pin 16 the car will always run at the higher rpm.

3) +12v to pin 19, ground to pin 16 applied and removed at the same time. Regular idle is 850rpm. When compressor is turned on (+12v on pin 16) and the DME is told AC is activated (ground on pin 19) the idle bump happens and the engine idles at 930rpm. When the AC is turned off (no power to pin 16, ground removed from pin 19) then the idle drops back down to 850rpm.

So while some people with different DME can luck out by permanently grounding the black/grey wire, I am not so lucky. So I need to put together a relay that will ground pin 16 when pin 19 gets +12v and my problems are solved!

[pandaboo911]

Here is an update and a bunch of test results

Thanks for this detailed reply from pandaboo911 I was finally able to understand the missing piece of the puzzle. You need to ground the AC activation pin the same time you turn the compressor on so the DME does the idle bump.

http://www.r3vlimited.com/board/showpost.php?p=4610626&postcount=327

My DME is a MS41.1
AC activation input is black/grey and is pin 16
AC compressor turn on input is violet/grey and pin 19

Testing results:

1) +12v to pin 19, nothing connected to pin 16. This is where most of us are stuck. We get AC but when we get to a stoplight the idle hunts, rpms drops and we may get some shaking happening. So no idle bump.

2) nothing to pin 19, ground to pin 16. My standard idle is 850rpm, with pin 16 grounded the idle is around 930rpm. Remove the ground and the rpms drop to 850rpm. HOWEVER, if you permanetly ground pin 16 the car will always run at the higher rpm.

3) +12v to pin 19, ground to pin 16 applied and removed at the same time. Regular idle is 850rpm. When compressor is turned on (+12v on pin 16) and the DME is told AC is activated (ground on pin 19) the idle bump happens and the engine idles at 930rpm. When the AC is turned off (no power to pin 16, ground removed from pin 19) then the idle drops back down to 850rpm.

So while some people with different DME can luck out by permanently grounding the black/grey wire, I am not so lucky. So I need to put together a relay that will ground pin 16 when pin 19 gets +12v and my problems are solved!

Sweet thanks for testing that. Now we can finally put an end to the confusion lol. Now we just need a guide for properly filling r134a by yourself, without having to monitor vent temps.

[Sh3rpak!ng]

Nice work guys and perfect timing. I've got all the parts waiting for install.

[MC Hammered]

So I just got this reply from my tuner (their comments in red) and I wanted to share it to get your thoughts.

It's been a while since your reply to me. I had time to dig around in the car to do testing, fixed the CEL for the catalyst code, and only how I was able to get to the point where I can activate the AC idle bump.

I just wanted to clarify your statement here: "I did verify that the idle RPM for AC is set to 850 in the tune, as is the normal idle."
Idle=850. Idle with AC on=850.


So when the AC is activated is my idle rpm supposed to stay at 850rpm?
Yes

Or is it supposed to be bumped higher?
Stock idle is very low. So is stock idle w/AC, although slightly higher than normal idle. I raise both to a level higher than stock, but keep them the same value.

Here is are some test results to explain what is happening:

My DME is a MS41.1
AC activation input is black/grey and is pin 16
AC compressor turn on input is violet/grey and pin 19
You’re missing parts of your circuit, sir. I’m happy to help but we charge for items like this, as this has nothing to do with your tune and is entirely related to the wiring of your car. We charge $120/hr, so it may or may not be worth it for you.

It is the "You’re missing parts of your circuit" that got my attention.

I know that we are hacking the e36 system to work with the e30, but what other "parts" could we be using other than the pressure switch?

[pandaboo911]

AC Idle bump

Wait so they said it didn't work? Why wouldn't they tell you what's missing lol

We need someone with stock idle to test this damnit

Sent from my iPhone using Tapatalk

[Mwishlist]

Nevermind, I just realized the answer.

[Mwishlist]

So I just got this reply from my tuner (their comments in red) and I wanted to share it to get your thoughts.



It is the "You’re missing parts of your circuit" that got my attention.

I know that we are hacking the e36 system to work with the e30, but what other "parts" could we be using other than the pressure switch?

There is a Compressor Control Relay on the e36 cars, K19. It's on page 269 of my ETK (1998 e36). Maybe that is what they refer to as being missing? It looks like Abie199 basically recreated this relay for the E30.

From the ETK:
The pressure switch drives the grounding on Pin 16 of the ECU (Activate AC) through Pin 5 on the X20.
The Automatic Climate Control drives the +12v on Pin 19 of the ECU (AC ON Signal) through Pin 6 in the X20.
Then the K19 relay is driven by Pin 74 of the ECU (Activate ECU Compressor) through Pin 4 of the X20 (I think if I am reading this right?).

This troubleshooting post from Bavauto seems to confirm.

http://blog.bavauto.com/6932/bmw-e36-3-series-air-conditioning-compressor-inoperative-ac-not-turning-on/

Anyway, I think implementing the relay like Abi199 did by triggering it off the AC switch not the ECU is the final answer. Although I am not that great at relays. I'm getting ready to hook up my AC in the next few weeks so I will see if I need to figure this out.