00523 IAT Sensor - Temp High - Circuit Low - G42 A 00525 O2 Sensor - Voltage Low -G39 B think reason it didnt decode the 2 you had before is it will only show 2 codes max on demo version, 2nd time only had the 1 code so no issues. hopefully these were old issues which were not cleared. sometimes an engine needs a good thrash to clear itself if its been sat, or if past running issues have coked up the bores/plugs a bit. some of the mk3 engiens do 'learn' but not sure about the 2e
What's an IAT sensor? I've run the car about 300 miles since i cleared the codes and have checked them again this weekend. No new fault codes which i guess is a good thing. To my novice head that implies that my idle issue, lower than expected mpg (31 combined) and stinky exhaust could be down to either a sensor not providing a correct reading or something purely physical. I'd like to start exploring the block measurements to see if any unexpected or out of tolerance values come up. Looking at the VCDS manual, this seems a bit of a labyrinth. Anyone got any tips of what to look for and which groups to examine? Cheers
inlet air temp sensor if you go into measuring blocks it should hopefully tell you what they all mean, or tyou will at least be able to figure it out by looking at the values, i.e. something in degrees is gonna be ecu or air temp, looking at the value it should be obvious which is which and/or disconnect sensors to see if it changes.
Ok, i've had a good look at the blocks with the car on warm up through to operating temp. A couple of things stand out: Coolant temp on VCDS largely tallies with the dash for a bit but when the car is up to temp, the dash sticks at 90 (it NEVER goes above 90) and VCDS reads the temp continuing to climb up to about 104ish. I appreciate the dash isn't going to be as accurate as Vagcom but that discrepancy is quite marked. The car has a 4 pin sender. The earths on the senser loom have been chopped and bullet connectored (soz if i already mentioned that). I'm getting increasingly convinced that this may be causing the temp sender to give dodgy readings so i am going to get the soldering iron out and make them as good as i can. Sadly i'm unable to find a wiring diagram for the sensor loom. The ignition timing is all over the place! I appreciate that the ECU will vary the timing to suit conditions but it swings about wildly when you press the accelerator. At idle it hovers around 2-4 degrees then gets up to about 30 degrees at 2.5-3k. When you lift off, it goes negative (-4) for a second or so before again settling around 2-4. Is that normal??? Throttle body angle seems ok. It reads 0 degrees at idle anyway.
the dash/ecu temp looks close enough to me, i think the mk3 dash is a bit liek the mk4 in that 90 actually is more like 80-110. the mk4 gague isnt linear at all, in order to prevent the driver getting scared the car isnt runnign at exactly 90 degrees
