Hi All. To keep it in a nutshell, had a misfire/running problem, changed just about everything on the "spark" side of things with no effect, I unpluged the ACT sensor, the engine note changed, the running problem has gone, plug it back on, the engine note drops and it misfires when you rev it! So changed the sensor, its still the same! As soon as I unplug the sensor, it runs ok.[compared to what it was doin!]
Any ideas?
Cheers

 

as far as i know there is a tie up between the act and cts sensor(the blue watertemp one).if one or the other fails, depending on which one is faulty the ecu subtitutes fixed values on the failed one depending on the readings from the good one,and if both fail then it still substitutes a set value for both, i dont know if only applies to standard ecu's
but it might be worth changing the cts sensor just to see if thats the one with the problem as opposed to the act one.

 

The main corrective factor for the co is the CTS, the air temps does very little in comparison the the cts.
If the cts is over a 3 or 4 years old I always change them anyway as they are so critical, so wouldn't be a bad move.
tabetha

 

The Weber ECU can only spot a fault with those two if they're open or short circuited. In the event of an open or short circuit, values are substituted as 40 degrees C for coolant, and 15 degrees for air.

 

i have slightly different values for a double sensor failure, if you have a single failure or shortcircut in either sensor the ecu applies the following.

with ats failure and cts < 47'c...... ats value is set equal to cts value
with ats failure and cts > 47'c...... ats value is set at 47.5'c

with cts failure and ats < 30'c...... cts value is set equal ats value
with cts failure and ats > 30'c...... cts value is set at 90'c

with a double sensor failure the values applied by the ecu are.. ats 47.5'c and cts 90'c

i not sure if this is for L1-6, L8, P8 or all of them. if all else fails replace both to be sure to be sure.

 

Agreed