Coolant temp weirdness ...
drove home from work thismorning, giving it a bit was at 90c, pulled up at some lights and it droped off back to 60c, till 5mins later when i reversed on my drive! checked under the bbonnet quickly at 5.30am coolent level ok, pipes nice and hot, so i guess im after a temp sendor? any pictures of where this is? part no? rough price?
Last edited by fil on Thu Mar 22, 2007 3:10 pm, edited 1 time in total.
99 S4 minging blue avant
Guys,
Something you need to bear in mind is that coolant sensor fitted under the MAF has two sensors, one sensitive sensor for the ECU and one insensitive sensor for the dash. Reason for this dumbass approach is customers complain if the dash temperature reading fluctuates apparently....so Audi fit two sensors.... If your VAGCom/ECU reading is stable then you shouldn't have any cold start/running or fuel consumption issues. If your car has started using more fuel then definetly worth checking/replacing the sensor under the MAF.
There is another temperature sensor over the other side, the afterun temperature sensor. This is a 2 pin sensor. Also definetly worth changing, keeps water circulating through the turbos after the engine stops if the coolant is above 93 deg C. I think the standard sensor is 110 deg. C and IME never switches on. With 93 deg. C sensor during the summer months the afterun pump trips quite often.
Something you need to bear in mind is that coolant sensor fitted under the MAF has two sensors, one sensitive sensor for the ECU and one insensitive sensor for the dash. Reason for this dumbass approach is customers complain if the dash temperature reading fluctuates apparently....so Audi fit two sensors.... If your VAGCom/ECU reading is stable then you shouldn't have any cold start/running or fuel consumption issues. If your car has started using more fuel then definetly worth checking/replacing the sensor under the MAF.
There is another temperature sensor over the other side, the afterun temperature sensor. This is a 2 pin sensor. Also definetly worth changing, keeps water circulating through the turbos after the engine stops if the coolant is above 93 deg C. I think the standard sensor is 110 deg. C and IME never switches on. With 93 deg. C sensor during the summer months the afterun pump trips quite often.
99 Ming Saloon, Tanoga S/S, De-cat APR D/Ps, Miltek catback, Forge DVs, RS4 suspension, K04s, I/Cs, MAF, Clutch, injectors, oil cooler, airbox, Y pipe, spark plugs, front brakes, Vast EFK, Walbro fuel pump, MRC custom tune, 18" B7 RS4 reps, Kumho tyres
anyone got a link for this after pump run mod?
edited to answer my own Q?
http://forums.audiworld.com/s4/msgs/1629709.phtml
unless anyone knows of a better guide?
edited to answer my own Q?
http://forums.audiworld.com/s4/msgs/1629709.phtml
unless anyone knows of a better guide?
99 S4 minging blue avant
Only thing I would add is that make sure you take the old O ring out, they tend to get stuck in the housing, new one wont fit until it is removed...
99 Ming Saloon, Tanoga S/S, De-cat APR D/Ps, Miltek catback, Forge DVs, RS4 suspension, K04s, I/Cs, MAF, Clutch, injectors, oil cooler, airbox, Y pipe, spark plugs, front brakes, Vast EFK, Walbro fuel pump, MRC custom tune, 18" B7 RS4 reps, Kumho tyres
Looking through old posts on this there seem to be a lot of variables - faulty thermostat, temperature sensor, gauge ...
I have the afterrun cooling mod but it never seems to kick in. Even after really hard driving I've never seen the oil get as hot as 90. Is there any systematic process to work out where temperature problems might lie?
Also, is the aircon display just as good as VAG-COM for checking thermistor values?
I have the afterrun cooling mod but it never seems to kick in. Even after really hard driving I've never seen the oil get as hot as 90. Is there any systematic process to work out where temperature problems might lie?
Also, is the aircon display just as good as VAG-COM for checking thermistor values?
RS6 Avant (C5), Daytona grey
Gone but not forgotten: S4 Avant (B5)
Gone but not forgotten: S4 Avant (B5)
Afterun mod cuts in if coolant temp >93 deg C when ignition is shut off, not the oil temp. It is officially designed to stop air bubbles forming in the coolant system, however when modified makes a good oil protection device for the turbos, much cheaper and easier than fitting a turbo timer.
If you haven't got the oil temp above 90 deg C you aren't trying hard enough
I think the aircon display shows ECU values, never tried it though, I always use VAGCom, for checking such things.
If you haven't got the oil temp above 90 deg C you aren't trying hard enough
I think the aircon display shows ECU values, never tried it though, I always use VAGCom, for checking such things.
99 Ming Saloon, Tanoga S/S, De-cat APR D/Ps, Miltek catback, Forge DVs, RS4 suspension, K04s, I/Cs, MAF, Clutch, injectors, oil cooler, airbox, Y pipe, spark plugs, front brakes, Vast EFK, Walbro fuel pump, MRC custom tune, 18" B7 RS4 reps, Kumho tyres
kayGee - Is there an easy way to identify the "sensitive" sensor from the "insensitive" one? I replaced one but I don't know or remember which! I have a cold-start issue and am wondering if I need to replace the "sensitive" one based on your description.
Also, you wouldn't happen to know the part number would you? (pushing my luck now, I know!)
Also, you wouldn't happen to know the part number would you? (pushing my luck now, I know!)
First off VAGCom your car to look for codes. Cold start issues can be the fault of all sorts of issues, however the coolant sensor is the cheapest of the lot.
No its a combined unit, 4 pin. Sits under the accordian hose. Use the green sensor (more reliable) when replacing rather than the blue one.
http://www.audiworld.com/tech/eng.html
No its a combined unit, 4 pin. Sits under the accordian hose. Use the green sensor (more reliable) when replacing rather than the blue one.
http://www.audiworld.com/tech/eng.html
99 Ming Saloon, Tanoga S/S, De-cat APR D/Ps, Miltek catback, Forge DVs, RS4 suspension, K04s, I/Cs, MAF, Clutch, injectors, oil cooler, airbox, Y pipe, spark plugs, front brakes, Vast EFK, Walbro fuel pump, MRC custom tune, 18" B7 RS4 reps, Kumho tyres
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