Gearcon

Hi,

I have the Audi ELSA software with all the wiring diagrams, but cannot find the wiring for the analog temperature gauge on the instrument cluster.

Can anyone provide this please.

Thanks,

Joe

mishar

Engine temperature sensor is connected to Engine Control Module. ECM is connected with Instrument Cluster via CAN-Bus. No direct connection between the sensor and the cluster.

MP4.2+6.0

For OP, what is the issue you are trying to sort out? I ask because a common failure on Audis is the coolant temp sensor. Various folks on this board have had theirs go out. On a 4.2 (not not a W12), it is not a huge job if you know where to find it. Not sure on an S8. Is a gauge with no reading why you are asking? If so, I would change the sensor long before fooling with or suspecting the instrument panel side.

Gearcon

The reason I ask, I was having an idling issue and suspected the hydraulically actuated mechanical camshaft adjuster on one of the exhaust cams. So I changed this (without taking the engine out). Definitely an improvement but still erratic idling.

It seemed to coincide with the car reaching temperature and going into closed loop control. So I cut the wire from the temperature sender (located at the back of the block) to the ECM. This forced the car to run in open loop control, car now idles absolutely perfectly and maintains a lambda of 1.0 in all driving conditions.

A side effect of this 'fix' is loss of temperature gauge and also the car reverted to running in sport mode constantly, also the radiator fans turn on, safety measure as no feedback on temperature and the thermostat opens and remains fully open from start-up. Lambda of 1.0 - higher fuel consumption also.

So I'm integrating a micro controller to feed the temperature sensor signal directly to the temperature gauge. The controller will also send a temperature lower than normal operating temperature to the ECM when RPM drops below 1000 RPM - forcing open loop and stable idling. Above 1000 RPM the actual temperature will be provided to the ECM, allowing the cooling system to operate correctly and also allowing normal Drive mode to be used.

All I'm missing is the wiring for the temperature gauge, but can figure it when I take it out if need be.

The actual issue regarding the idling is proving very elusive, hence the above.

mishar

Have you scanned it?

MP4.2+6.0

I admire the ingenuity. But...I would probably go down other more conventional paths first. If it is acting up closed loop but not open, I would look at other areas working closed loop. O2 sensors (where I would expect a code) and MAF (maybe a code, maybe not) would be among the ones. Unplugging an MAF--and you would have two with the two air box S8/W12 set up--should also force open loop, plus maybe give you more info. Maybe air pumps that should be working early on (overlapping open loop) but not later on as it warms. Or maybe combi valves (if like a 4.2) that cross over between the air injection cold and EGR functions hot; codes likely here too. On an FSI motor like an S8, maybe valve fouling for that matter--more so since you suspected a cam issue, less so since you say open loop things seem better.

Gearcon

Hey there, working on sorting this. I'll go through the list you provided, thank you. I did scan it. This may of use to others ...

It's the calibration curve for the temperature sensor on the S8 (2006) part number 06A919501A. Best fit through five points.