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Fixing an idle air control valve/idle speed actuator
A precise mini digital oil temperature gauge
VW 35i/B3-B4 - Rebuilding an air condition temperature sensor/fan
A very simple GPS-mounting for my bike
Idle air control valve/Idle speed actuator
After 22 years of working life this thing broke. The genuine Bosch part costs circa 180€. So I orderd a spare part for about 25€ which worked flawlessly for one year. One day my car, when in idle-cut-off operation, starts self accelerating for about a second as engine speed was getting below 2500rpm.
Let's go to fix this issue. Carefully unhook the PVC clips using 7 small screwdriver bits or something like that to devide both halfs. Be very careful or else super glue again will be your last resort. If you don't own VAGCOM mark all gear wheels so that you can find their default positions if you accidently did turn one of them. Too late? No problem at all. Detach the motor and turn the big white wheel to the left 'til it stops. Reatach the electric motor, set the worm drive to the middle and your'e good to go.
Please get me to the fixing! Ok, now check the "Kontaktzungen" and clean them with gasoline soaked Q-tips. Do this with the "Hallnehmer" stripes. Now you have two options: First one is to assemble everthing until, after 6 to 8 month, the same fault will enter the stage again.
Second option: Check the "Kontaktzungen" wether they are loose (wobbling). If so, first make sure, that they're correspondend to the "Hallnehmer's" lines and then stick them with one (one!) drop of super glue - just between their backsides and the edge of the circle. And now take a closer look at the bottom of the "Ringmagnet". When going into idle the motor turns the "Hallgeber" to the bottom and connects both "Kontaktzungen" so the engine gets an idle signal. Plaese make sure with a multimeter that this short can be achieved. If so, assemble all parts.
This circuit is connected to the TPS (Throttle position sensor) on the BOSCH MONO MOTRONIC - to a distinctive poti that reports the throttle valve's position to the ECU.
Oil temperature gauge
Have waste spare time? Then this is right for you! The 90hp B4 definitely doesn't need an oil temperature control gauge. I discovered a cheap but ultra precise thermometer with an innovative new sensor. And I discovered that in my B4's engine there already is a port for a temperatuer sensor. And then there were 2 dummy switches in the dashboard.
Ok, let's give it a try. The measuring range of this thermometer extends from -30 to +125 C degrees with a resolution of 0.1 degrees between 0 and 100 degrees and a deviation of less than 0.5 degrees. Below -9.9 and over 99.9 degrees, the decimal place is switched off. From up to 125 degrees HHH appears but the sensor stays healthy. The probe is not, as usual, an NTC, but a calibrated IC from Dallas. This comes with 3m lead and a waterproofed sunk in a stainless steel tube. The price is between 10 € (directly from China) and 28 €. The display is available in the colors yellow, green, red and blue. Compared to the other displays and other lighting green appeared to suit. Ah, I used high temperature two component glue to fix the new stab sensor into a drilled out genuine engine sensor screw. The engine has never reached 125 degrees C so far. This mod simply is superfluous but fancy and reliable and precise as predicted.
Rebuilding an air condition temperature sensor/fan
You get an error code "00796 V42" and/or "031c BEMO" on your climatronic display? Don't worry, that's what all websites are telling you. Just blow the dust off from the fan's blades. In my case this did not cure the error and failure. I examined the whole unit and found, to be true and honest, nothing that had lead me to a reliable solution.
So I tried to rebuild this unit from scratch because OEM's parts no longer are available. I discoverd that the fan was sending a tacho signal to the air condition control unit. Lucky me it wasn't already dead so I could identify the fan's signal type between the yellow wire and ground (the black wire): A square-wave at abaout 400Hz. So I did some tests with PC-cooler fans and bought a tiny (4x4cm) SUNON fan. I removed the original fan from it's mounting plate and attached this new one to it.
This SUNON fan was rotating at 10000rpm. Sirrrrr. In a first attempt I used a load resistor to reduce the rotation speed which did the trick but the resistor became pretty hot. Finally I used a 7 Volt voltage regulator to reduce the fan speed. Last but not least I replaced the temperatuer sensor with a proper NTC - a 3KOhm-type.
A mounting for my cell phone
A short piece of a thin rubber hose, a fuel pipe and superglue. The main plate holding the mobile/GPS can easely be detachted from the ground plate. It can be affixed and removed without any tool. It's soundly based, yet flexlible and it absorbs hard impact from the front fork.
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