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AllShoNoGo
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Discussion Starter #21
right here is why I always liked you man
"I always do my thing on the tex.... despite if people are watching or not.... listening or not.... building or not..... I'm always doing my own thing there"

Awesome build thread Phil...everyone rockin Rados makes me miss mine more:(
I'm in the middle of a G60T "mess" in the ol' Jetta...:D
 

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I see a description about the black and blue sensors in the flange but I have a white
sensor also in the smaller flange on the end of the block going to the heater core hose. I just noticed it has no plug anywhere that I can see in my engine bay and is just doing nothing. What is the purpose of the sensor in the digifant system and does anything act quirky if it is not connected?

whitesensor2.jpg
 

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AllShoNoGo
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Discussion Starter #23
what years the car? I'm on my phone and can't quite focus in on your pic
 

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Latter 1989, early 1990. 1989 for all intents and purposes. There are two wires going to a bolt on the flange (u can see in the pic) that I assumed to be some type of ground. Would those possibly be the leads? VIN is WVWRB11G2KW....
 

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That sensor isn't involved in any engine management and has nothing to do with digifant (or cis, etc)

that sensor, IIRC is for AC fan control... your car had AC at one point eh?
 

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It has functioning AC right now. I don't see a plug anywhere to this sensor though. I do see two wires going to a bolt on that flange and wondered if they were the wires that are supposed to go to the sensor plug if that plug existed in my car - see that pic I included. this is what I see online about that sensor.


Water Temp. Sensor

A/C Cut-Off
With Digifant
(119c 2 Pin, Grey/White) Mounted in water flange at cylinder head.
 

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the car has working ac. This sensor has always been there but there's no plug to it and I can't tell where any wires that go the sensor might be located. The fan is ALWAYS on and on high when the AC is on.With the ac off it functions sporadically on and off within seconds, on too long after the car is turned off...Thanks guys
 

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Digifook.
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I thought I would chime in some Digifant advice that I didnt read much up on yet in this post or in any other online sorce. Im in no way Hi jacking, just contributing good info and advice. In particular this applies to the Digi2 in Mk2 cars. The Digi system on the Audi 5 cylinder engine, also used in Euro Vans is the same principal but the wire points differ.

Grounding: Its the major cause of any issues, easily fixed and maintained in these cars. Everyone is told to check the grounds but half of them are easily overlooked and only the less crucial ones are fixed.

Ground points under the hood:
Brown/black two wires into one connector - Valve cover stud or coolant flange - fuel injectors.
Brown/white two wires into one connector - Valve cover stud - sensor grounds.
Bare wire braid/sometimes covered coming out of O2 sens harness - valve cover stud - O2 sens sheilding ground.
Flat strap covered in plastic - valve cover stud - body ground for cowel and roof.
Thick bare wire OEM - bell housing to post behind battery to battary negative - main engine / starter ground, body ground.
x2 seperate Brown - harness to battery negative - one is ECU ground, one is Ignition Modual ground.
Thick brown - Fuse block ground. Z2 connection on block to battery.

As much as its important to have clean ground connections the ones on the engine itself are very low current. Excessive dirt or corrosion will impede them and the engine managment will suffer from that. The biggest and most common ground issue is the main engine ground. The bell housing connection is the one that stays the cleanest since it is very large but alot of these cars by now have had the origional battery cable end replaced with the cheap style that sandwitches the wire/wires with 2 bolts. These are higher resistance to begin with and also get corroded really quick due to the nature of batterys venting. The alloy is also very soft to allow it to fit snug to a varity of post sizes. You will find they loosen off and stretch out really fast. If you have to use a clamp like that crimp on a battary cable ring connector and seal it with heat shrink of according color for ID. Then bolt that to the cheap connector. Unless its been replaced recently any OE battery cables should be repalced. Positive or negative.

The ECU and ignition module ground are direct to the battery as they have a higher draw of power and need the best possible ground. You can ground them to the body, or engine but you will feel that wire get really warm, really quick. Because they come out of the harness at the battery its virtually impossible to mis place them.

The Sensor and injection grounds will work just fine at the valve cover stud, or on the coolant flange stud.

A very big mis conception is that the flat strap going to the valve cover is the ECU or Coil ground. It mearly shares a bolt from the coil bracket and is only a static ground.

Adding redundant grounds:
Its often advised to add a redundant ground that bridges the sensor grounds to the bell housing or the battery itself. On my own car I tested the theroy and noted no change at all. Before removing it I tested the resistance between the according ground on the main engine harness at the ECU and the battery. All the engine mounted grounds outside the bell housing to battary ground had higher resistance than if just left stock. I later tested this again with 2 friends cars with typical Digi issues that ended up being partly grounding and partly other reasons.

The only worthwile addition or change to the grounding is with the main engine ground itself. From factory it ties in to the post behind the battery and then to the Battery itself. This works just fine on a bone stock car. A well paid team of engineers came up with it, tested it and said it would work. If you have had to replace the entire cable at one point and a factory one wasnt used that crucial body ground is left open. If you have swapped to a Quad round light set up where the relays, and 4 bulbs are now grounding into the battery you will require it and even the stock one is now not quite up to par. In most cases having two thick cables, one from the bell housing and one from that post works really well. Headlights are usually brighter for it, somthing I noticed even in my own car. Its also a good idea to go with this method if you have added an amp and sub box to the car and grounded it to the body somwear.

Dialectic paste:
VW recomended using stabilant on all connections under the hood. This was mainly because non of the connectors at the time were well sealed compared to modern cars. There is also no noticeable resistance differance if you coat the threads or connections prior to install. If you used a paste other than stabilant on the threads or connections you can actually add more resistance, particularly in a low power ground or connection. If you have clean connections putting a thin layer of any dialectic paste or even anti sieze over top to help sheild it works just as well and is far less messy.

Cleaning all the ground, espessialy the battery itself - positive and negative - is almost allways been done the lazy way. Simply blasting it with brake clean and wiping it off after wont do. It should be phisically taken apart, lightly sanded clean, then sprayed and wiped. Frequancy will depend on climate to some degree but even in the wettest places on earth once a year is plenty. Frequancy is also effected by the cleanliness and maintance of the engine itself. IE if your valve cover gasket is not doing its job you will have to clean the grounds in that area more often. To clean the main connector at the ECU and Ignition module simply remove, spray with contact cleaner and re install it. They are typically well sealed.

Since most ground issues originate at the battery cables themselves finding a battery bag is one of the easiest ways to keep things clean. Another cheap and productive measure with any car is to replace all the ring connectors with equally good quality ones. Crimp them on the way they came from the factory with the propper tool, avoid the cheap crush and go versions with the plastic sheilding, and add a bit of heat srink over the crimp surface. This will help keep the bare wire cleaner aswell as providing more strenth to the joint so the likleyhood of the wire breaking off at the crimp is far less.

One of the main overlooked ground is the fuse block ground itself. The fuse block is located right above were wet floor mats and shoes created a damp enviroment. Most of the grounds within the block arent very high power but all suffer corrosion. Things like a stereo, the wiper motor aswell as factory wiring for fog lights run thru the block and then to the battery. Its also worth while if you have factory fog light wiring to find the connector under the coolant bottle where the wiring for the lights is split for left and right. Those connectors get particularly corroded. Cleaning it makes a world of differance. Adding a thicker piece of heat shrink over the whole connector helps a great deal.

Hope this is helpful to anyone with Digi woes, or just looking to keep their car going strong.
 
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