I've searched and read and read some more but couldn't find anything conclusive. This issue has been bugging me for the past cpl weeks and my attempts at resolving it have so far been fruitless. So, here's to hoping the veterans can help.
I acquired my 2003 1.8t fwd only a few months ago so I'm not sure if this is an older 'problem' or if it just started.
Since the nights started getting colder, any time the car sits for 10 or more hours in temperatures below 4ºC (39ºF), there is no 'autochoke' on startup - meaning there seems to be no air/fuel adjustment from the ECU for a richer mixture during warm-up.
Normally, at cold start, the RPM raises to about 1200, fuel flow (as indicated by the MFD) shows ~4liters/hour and the vacuum/boost gauge indicates a stronger vacuum of about 10inHG - they gradually drop over the course of a minute while the engine heats up and settle at ~800rpm, ~1L/hr and 19inHG, at idle.
What it does instead is act as if it's already half-way warmed up: ~900-ish RPM, ~2L/hr and 17-18inHG vacuum at idle.
This doesn't happen for subsequent start-ups during the day, even if the car sat for 8 hours or if the engine is still somewhat warm - it still goes through the 'autochoke' period as it's supposed to. It only acts up on cold mornings of after sitting for extended periods of time.
My several attempts at resolving this problem include replacing the CTS, cleaning and realignment of the throttle body (including replaced gasket) and cleaning the MAF sensor.
Thanks for reading - hope someone is able to point me in the right direction of possible problem areas to look at.
PS: I don't have a VAG-COM but it's on my list of things to get a hold of in the near future. What should I look for with the VAG-COM if I had one now?
I acquired my 2003 1.8t fwd only a few months ago so I'm not sure if this is an older 'problem' or if it just started.
Since the nights started getting colder, any time the car sits for 10 or more hours in temperatures below 4ºC (39ºF), there is no 'autochoke' on startup - meaning there seems to be no air/fuel adjustment from the ECU for a richer mixture during warm-up.
Normally, at cold start, the RPM raises to about 1200, fuel flow (as indicated by the MFD) shows ~4liters/hour and the vacuum/boost gauge indicates a stronger vacuum of about 10inHG - they gradually drop over the course of a minute while the engine heats up and settle at ~800rpm, ~1L/hr and 19inHG, at idle.
What it does instead is act as if it's already half-way warmed up: ~900-ish RPM, ~2L/hr and 17-18inHG vacuum at idle.
This doesn't happen for subsequent start-ups during the day, even if the car sat for 8 hours or if the engine is still somewhat warm - it still goes through the 'autochoke' period as it's supposed to. It only acts up on cold mornings of after sitting for extended periods of time.
My several attempts at resolving this problem include replacing the CTS, cleaning and realignment of the throttle body (including replaced gasket) and cleaning the MAF sensor.
Thanks for reading - hope someone is able to point me in the right direction of possible problem areas to look at.
PS: I don't have a VAG-COM but it's on my list of things to get a hold of in the near future. What should I look for with the VAG-COM if I had one now?
Yes, the ECU is supposed to know what to do - but it acts on pre-programmed instructions relying heavily on readings it gets from various sensors.
