B5 RS4 EGT sensor woes?

[Monkeymagic]

When I bought my RS4 it flagged a fault on VCDS with the Exhaust gas temp sensor on bank 2. The car drives fine but I assume will be losing a few horses as a result. I have tried replacing the board with an S4 Sid one but I either killed it soldering it in or the problem lies In the wiring elsewhere. I regularly get a fault code saying the sensor is short to ground. I can clear it and on start up it re-appears. I am tempted to get a pair which will set me back £400. I have also considered mapping them out, however having spoken to MRC they don't recommend it as they are an important safety feature.
Has anyone got any experience of mapping these out. I'm not that bothered about spending the cash (although it still hurts) but they are a common failure and can get costly over time..anyone got any thoughts? Regards Steven.

[prj]

Can be removed from software, but for that the entire software needs to be altered.
If you just delete them without completely changing the fueling strategy on the car, you will melt down the engine on a longer WOT run.

[Monkeymagic]

Excellent news. Is there anyone you would recommend in the uk? There's plenty of mobile tuners but I'm extremely sceptical about them. I can't help but think that spending £400 to replace the sensors may be a false economy as they seem prone to failure. Thanks again

[Error404]

Dmitri can you tell us how the RS4 use the EGTs?
Is it an economy / emissions strategy to keep the AFRs leaner and use the EGTs to trim fuel to cool the combustion as required on WOT rather than a "safe" rich AFR target on WOT?

[Monkeymagic]

They are there to fail regular and make Audi loads of cash. Or am I being cynical.??��

[AndyP]

What's so special about them that they cost £400? Can you not just splice in a standard K type thermocouple? This is what I use as an EGT sensor, cost £10 off ebay 5 years ago and still going strong!

[Monkeymagic]

Nowt imo it's 420 plus at trade. I can get a pair for £400 on line.

[Monkeymagic]

Having just re-built the rear suspension changed the thermostat 4 wheel alignment and 2 new tyres the egt may have to wait. Combined with moving house the rs4 will have to make do for now. Apparently you can piggy back sensor 2 off sensor 1. For any other car egts seem relatively cheap.

[A1QSHIP]

If your are handy with a soldering iron you can usually repair them. It is where the sensor wire meets the circuit board that the problem usually exist. Carefully remove the non-removable cover & you will see where the sensor wire has come away from the attachment peg. I have fixed a couple of these this way.
Disclaimer, YMMV.
HTH, Chris

[david1980]

If your are handy with a soldering iron you can usually repair them. It is where the sensor wire meets the circuit board that the problem usually exist. Carefully remove the non-removable cover & you will see where the sensor wire has come away from the attachment peg. I have fixed a couple of these this way.
Disclaimer, YMMV.
HTH, Chris

Carefully remove the non-removable cover

What does YMMV mean?

I am also interested in knowing if the sensors really do that much, there is no way i'd do a massive long run on WOT, just small bursts every so often up to maybe 120ish if that

[newsh]

Your Milage May Vary

[newsh]

The cover is glued on
There's a groove in the plastic casing, run a knife round carefully and you can prise the cover off. The circuit board is encapsulated in some clear gloop, dig it away to resolder or fit a new circuit board. I've done a few of these for Stevie who was selling rebuilt ones on SRS

[le mans]

Dmitri can you tell us how the RS4 use the EGTs?
Is it an economy / emissions strategy to keep the AFRs leaner and use the EGTs to trim fuel to cool the combustion as required on WOT rather than a "safe" rich AFR target on WOT?

This from the B5 S4 study guide:http://www.ibiblio.org/tkan/audi/2.7...-SelfStudy.pdf

Exhaust gas temperature control
A new feature of Audi automobiles is a function which monitors exhaust gas temperature over the entire engine speed range.

For turbocharged engines, the maximum permissible exhaust gas temperature is a key design criterion.
To protect the exhaust gas turbocharger and the exhaust manifold, the exhaust gas temperature should not exceed 1000 °C for a lengthy period of time.
Since many of the components which influence the exhaust gas temperature have tolerances, thermodynamic adaptation previously took place at 950 °C for safety’s sake.
This was achieved by enriching the air/fuel mixture.
The exhaust gas temperature is recorded in a cylinder-bank-specific manner by the two exhaust gas temperature senders G235 and G236.
The Motronic controls the exhaust gas temperature to 980 °C by enriching the air/fuel mixture .
It is therefore possible to largely dispense with the prophylactic enrichment process that has been standard practice until now.
The mixture is only enriched...
... when necessary and
... to the extent necessary.
This means that engine operation with lambda = 1 is possible up to high load and engine speed ranges.
Advantage:
• Improved efficiency and reduction of fuel consumption as well as exhaust emissions.

[Error404]

[Monkeymagic]

I have soldered an S4 Sid board in and it's made no difference. I've re soldered others with success. Seems the fault lies elsewhere. I cruise everywhere at 60 and only really give it beans occasionally. Mileage is 108k with excellent history