ALH High Idle Switch For Rapid Warmup

[TDI Greg]

Hey guys,
I worked this winter to develop a high idle switch for the MK4 ALH. It is pretty straight forward and can be installed by a competent home mechanic. If you are running w/o egr it takes forever to warm your car at an idle from a cold start. This switch takes care of that by raising the idle to about 1500 (customizable) and closing the turbo vanes to retain engine heat a little better. I would be open to selling kits for the install but I'd like to know how many people would be interested before I get set up as a vendor or anything. These kits would be relatively inexpensive, probably less than $60 (don't hold me to it) if this makes any difference in your interest level.

 

[oilhammer]

I just drive the car. Not getting anywhere at idle anyway.

 

[scurvy]

I'm interested if it works for the BEW as well.

 

[n1das]

I thought about doing something like this for my 02 Golf TDI back in the day. I sold the car in 2010 at only 361k miles on the odometer to a coworker whose son needed a car for college. Fast forward to today and the car was recently sold to someone I know at work. It needs some work to get it on the road again but currently has only 428k miles on the odometer.

I was thinking of using the ECU's 1199 RPM governed high idle mode to do a high idle when desired. Basically you modify the go-pedal circuit so the ECU sees the pedal being pressed slightly and modify the brake switch circuit so the ECU sees the brake pedal being pressed. The ECU goes automatically into this mode when it sees go-pedal input and the brake pedal pressed. Once in this mode, the engine will maintain precisely 1199 RPM and the RPM is governed by the ECU. Loading the engine while in this mode causes the ECU to automatically increase fueling as need to maintain a precisely governed 1199 RPM.

I thought about doing a mod to implement this but but didn't bother because there isn't much need to high idle a TDI.

 

[TDI Greg]

I get that some people may not see a need for high idle capabilities, especially if you have a block heater. These cars sound bad if you just start them up at 15deg F and hit the road, but if you high idle it for 2-5 min (depending on ambient temp) they don't have the marble-in-engine sound.


This system is set up so the computer sees a maintained throttle position in stead of a commanded rpm, so the idle creeps up a little as the engine reaches operating temp.


As for the BEW I don't know for rock solid sure, but from the little research I did it looks like it should. I just need to find a guinea pig BEW.

 

[scurvy]

I just need to find a guinea pig BEW.

I got one that ain't doing much these days. Let's talk.

 

[KrashDH]

I get that some people may not see a need for high idle capabilities, especially if you have a block heater. These cars sound bad if you just start them up at 15deg F and hit the road, but if you high idle it for 2-5 min (depending on ambient temp) they don't have the marble-in-engine sound.


This system is set up so the computer sees a maintained throttle position in stead of a commanded rpm, so the idle creeps up a little as the engine reaches operating temp.


As for the BEW I don't know for rock solid sure, but from the little research I did it looks like it should. I just need to find a guinea pig BEW.

I think the high idle thing is awesome. I technically don't need it now that I'm in the PNW, but it's a sweet option to have.

My truck program has a high idle option when it drops below a certain temperature. Super useful when I was out in Montana and often temps were below double digits.

Always was curious about this for the car, but it was purchased out here and doesn't really get that cold. Nice work on a solution though

 

[Rob Mayercik]

Might be handy for when you have a lot of ice to get off the windows before you can see enough to drive (especially in states that have a "clear it off before you go" law, like NJ does), if it gets a little extra heat into the engine/heater core...

 

[n1das]

I get that some people may not see a need for high idle capabilities, especially if you have a block heater. These cars sound bad if you just start them up at 15deg F and hit the road, but if you high idle it for 2-5 min (depending on ambient temp) they don't have the marble-in-engine sound.


This system is set up so the computer sees a maintained throttle position in stead of a commanded rpm, so the idle creeps up a little as the engine reaches operating temp.


As for the BEW I don't know for rock solid sure, but from the little research I did it looks like it should. I just need to find a guinea pig BEW.

It sounds like you modded the go-pedal circuit so that the ECU sees a slightly above idle input. If you try stepping on and stay on the brake pedal with your mod enabled, the ECU should go into its governed high idle mode and run the engine at a precisely governed 1199 RPM. Letting go of the brake pedal while your mod is still on will cause the ECU to drop out of this mode and return control to the go-pedal and revert back to your set RPM. All you need to do is add a switch to trick the ECU into thinking the brake pedal is being stepped on and you'll have a high idle precisely controlled by the ECU.

The ALH ECU's governed high idle mode with the brake and go-pedal pressed together DOES NOT work with the BEW. The BEW's ECU behavior is differnt. Your mod should still work with a BEW if all it does is modify the go-pedal input to the ECU. My experience with the ALH and BEW have been in manual transmission cars. I don't know if the behavior is any different in automatic transmission cars.

 

[Mike_04GolfTDI]

That would be really handy for when I have to use the HIAB crane that I have mounted off the rear bumper of my Golf. Normally I have to get the missus to hold the throttle down a little, but after a while she gets all pissy and then I have to sleep on the sofa.

I use the crane to load all the toilet paper and bleach from Costco.