Curious...............
07-07-2013, 05:24 AM
#1
Racer
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Curious...............
Hi,
I am about to replace my Temp II sensor in my S4 MY89 since it looks like it is original and occasionally I get cold start issues (and infrequently some warm start issues). Roger recommends changing every 5 years and to treat as a consumable.
It got me to thinking what variety of symptoms that a failing or off-spec Temp II sensor would have in normal driving and apart from possible cold start issues. Let's assume it's not a hard failure and say that the resistance levels are reading higher for a given temp or even lower for a given temp. Will this affect things like:
1. Fuel economy - engine running rich or lean
2. Power delivery
3. Throttle response due to incorrect fuel metering based on incorrect temp reading
How does the software/firmware in the LH use this info at different operating temps.
Cheers
I am about to replace my Temp II sensor in my S4 MY89 since it looks like it is original and occasionally I get cold start issues (and infrequently some warm start issues). Roger recommends changing every 5 years and to treat as a consumable.
It got me to thinking what variety of symptoms that a failing or off-spec Temp II sensor would have in normal driving and apart from possible cold start issues. Let's assume it's not a hard failure and say that the resistance levels are reading higher for a given temp or even lower for a given temp. Will this affect things like:
1. Fuel economy - engine running rich or lean
2. Power delivery
3. Throttle response due to incorrect fuel metering based on incorrect temp reading
How does the software/firmware in the LH use this info at different operating temps.
Cheers
07-07-2013, 11:06 AM
#3
Rennlist Member
Rennlist Site Sponsor
The Temp II sensor is a "trim" input - that is, it tells the LH ECU what the coolant temp is, and the ECU slightly adjusts the mixture. (The Temp II also causes the EZK to trim the ignition timing slightly.)
The most visible effect is usually at starting. If the sensor or the wiring is faulty, either cold starting (too lean) or hot starting (too rich) can be difficult.
If the sensor incorrectly tells the ECUs that the engine is cold, they will never go to closed-loop, with poorer fuel mileage and higher emissions.
The most visible effect is usually at starting. If the sensor or the wiring is faulty, either cold starting (too lean) or hot starting (too rich) can be difficult.
If the sensor incorrectly tells the ECUs that the engine is cold, they will never go to closed-loop, with poorer fuel mileage and higher emissions.
07-08-2013, 08:43 AM
#5
Rennlist Member
Tony,
By all means keep a spare temp 2 sensor in the kit. very easy to remove and check calibration of what you have temp versus resistance. I dare say intermittent faults are also possible The main thing to bear in mind is that all these cars a old and the wiring is in various stages of dilapidation which in turn can cause the signal to be corrupted.
Inside the LH [and EZ units?] are warm up maps that the system references and the algorithms compute how much signal [pulse width] to put on the injectors compensated for temperature. Bigger corrections are used for lower temperatures and by the time the unit is at 80C the correction is minimal and reverts to zero at 86C [fully warmed condition] if my memory serves me correctly. Not sure what the percentage adjustment works out at for given temperature bands.
I recently had a cold start issue after fitting custom injectors and was able to solve the problem by increasing the settings on the warm up map. I simply started the engine and using my sharktuner kit simply increased the map settings [to achieve a stable response] in each temp band range as the motor progressively warmed up. The motor once more fires up without any cold start issues.
It would be interesting to know just how much extra fuel [percentage wise] is added at say 0 degrees C if anyone happens to know how that translates. I presume the additive mapping values are pretty much the same unit values as they are in the normal operating cells. I suspect it is not a big difference but then I do not get to see very cold temperatures over here to monitor such.
Regards
Fred
By all means keep a spare temp 2 sensor in the kit. very easy to remove and check calibration of what you have temp versus resistance. I dare say intermittent faults are also possible The main thing to bear in mind is that all these cars a old and the wiring is in various stages of dilapidation which in turn can cause the signal to be corrupted.
Inside the LH [and EZ units?] are warm up maps that the system references and the algorithms compute how much signal [pulse width] to put on the injectors compensated for temperature. Bigger corrections are used for lower temperatures and by the time the unit is at 80C the correction is minimal and reverts to zero at 86C [fully warmed condition] if my memory serves me correctly. Not sure what the percentage adjustment works out at for given temperature bands.
I recently had a cold start issue after fitting custom injectors and was able to solve the problem by increasing the settings on the warm up map. I simply started the engine and using my sharktuner kit simply increased the map settings [to achieve a stable response] in each temp band range as the motor progressively warmed up. The motor once more fires up without any cold start issues.
It would be interesting to know just how much extra fuel [percentage wise] is added at say 0 degrees C if anyone happens to know how that translates. I presume the additive mapping values are pretty much the same unit values as they are in the normal operating cells. I suspect it is not a big difference but then I do not get to see very cold temperatures over here to monitor such.
Regards
Fred