hey guys as title states idle plays up when pulling up at traffic lights then settles? seems to be gettin worse? cant find any leaks or anything? no other issues really, one thing i just noted though is the coolant temp sensor is black? everyone else seems to mention blue or green? any ideas why mine is black and could this be the cause of the irratic idle? no faults codes on laptop scanner but dont have vagcom? hope all this helps cheers zak.
idle issues?
- Thread starter Zman6000
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Car? year? engine code?
Black CTS is an older version but depending on the car you have you may have 1 or 2 sensors..
Erratic idle is more commonly from an airleak... check all pipes for splits especially under the inlet manifold
<tuffty/>
Black CTS is an older version but depending on the car you have you may have 1 or 2 sensors..
Erratic idle is more commonly from an airleak... check all pipes for splits especially under the inlet manifold
<tuffty/>
Audi A3, 1999, 1.8t sport Quattro. I only think there's the one coolant temp sensor? The other will be the gauge sensor won't it? Thanks tufty.
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The sensor is dual channel typically so feeds the ECU and instruments
Check for air leaks
<tuffty/>
Check for air leaks
<tuffty/>
Checked for air leaks buddy many many times, several hoses replaced them no avail, sprayed many sprays in many areas none affect the running of the car? Zak.
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Smoke tested?
If you are 110% confident that you have no airleaks (not that I don't believe you but I can count the number of leak free cars that have come through Bills on my hand) then you will have to look at logging in VCDS to see whats going on...
As for the CTS... you need to understand why this 'may' be causing an issue... a faulty CTS could under read so the ECU thinks coolant temps are lower than they actually are and still be in cold start/warm up mode... this will make the AFR run rich and subsequently cause issues with how the engine runs..
Logging coolant temps when the engine is obviously warm should confirm this... else you will need to check fuel trims and see if there is any excessive adaptions that could indicate an airleak
Other possible candidates are MAF, O2 sensor, injectors, plugs etc... you just to be systematic and ideally have VCDS (or something thats at least capable as most stuff varies wildly in capability) to hand to be able to see what the ECU is seeing
<tuffty/>
If you are 110% confident that you have no airleaks (not that I don't believe you but I can count the number of leak free cars that have come through Bills on my hand) then you will have to look at logging in VCDS to see whats going on...
As for the CTS... you need to understand why this 'may' be causing an issue... a faulty CTS could under read so the ECU thinks coolant temps are lower than they actually are and still be in cold start/warm up mode... this will make the AFR run rich and subsequently cause issues with how the engine runs..
Logging coolant temps when the engine is obviously warm should confirm this... else you will need to check fuel trims and see if there is any excessive adaptions that could indicate an airleak
Other possible candidates are MAF, O2 sensor, injectors, plugs etc... you just to be systematic and ideally have VCDS (or something thats at least capable as most stuff varies wildly in capability) to hand to be able to see what the ECU is seeing
<tuffty/>
Thanks for the reply, no it hasn't been smoke tested and I can't find anyone in the local area that has one? I may be able to get my hands on vcds, anyhow it's 90% better now, next to the throttle is a little sensor removed that and it was absolutely caked in oil/debree, cleaned with brake and clutch cleaner and also did the throttle at the same time, pull up at the lights and it doesn't dip nowhere near like it did before so gonna completely remove it and give it another blast through, 81,000miles of toodling around in 17years is deffo enough to carbon/oil things up wouldn't you agree?
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Oh and is the black sensor prone to be faulty like the previous blue ones or not? I understand the principles and operations of most components/sensors in cars/combustion engine some just affect the operation of others (as you well know) and without a vcds and being able to log certain things I'm kinda screwed half the time and have to go with experience and knowledge (Of what I have lol)
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Air temperature sensor... this can effect running too but issues are not as common with these
The green CTS sensor is the replacement for the previous ones as they are prone to issues... I am not one for suggesting replacement of stuff without more information from logging/codes etc but the green sensors are more reliable (unless you buy a cheap pattern part)
VCDS is massively useful and can be bought relatively cheaply all things considered... it can be difficult to justify but it tends to pay for itself fairly quickly
<tuffty/>
I wasn't suggesting just to replace parts buddy just merely asking if the black cts sensor is prone to failing same as the blue cts sensor? Haven't heard anything about the black cts sensor and as you can see I was quite surprised it wasn't blue or green? I think it's time to bite the bullet and buy a vcds. When I worked for mg/rover dealership it was part vw and we had a handheld little blue diag that was vw that was pretty awesome I'll pop up and see the gaffer see if they still have it I bet that will show me everything fingers crossed!
