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Car rpm is dropping in the winter morning

pixelord

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Hi,

For last 3/4 days (it is very cold in the morning and evening in Melbourne), my cars rpm is dropping and engine is stalling when I first start my car.
It looks like rpm is too low to keep the car running!

But if I keep pushing the paddle to keep it running for a min or two, the rpm goes normal and got no issue running?
Is it common in winter? How to fix it?
 

Tree cutter

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Sounds like the idle air control valve is clogged up. Cleaning the throttle body will fix it if this is the problem.
 

stuntmanmike

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Yep.
That is the ECU "cold start" cycle and corresponds with the engine temperature sensor.
Tree cutter may be right too. The IACs do become clogged with varnish and gunk with time.
Some may speculate to say it's the temp sensor or O2 sensor or something else that is failing (who knows without testing?). If your intake air filter is to be replaced then it could improve things (perhaps marginally). If your car is parked outside overnight then move it to an enclosed space if possible. This will assist start up on cold days.
Perhaps changing components might not improve anything (especially when it warms up again in later seasons).
Have you checked for error codes to see if anything abnormal shows up (e.g. O2 sensor etc)? Usually a good starting point.
Could be nothing to be concerned about and might save you some money if there's no real issue. Some businesses like to say it could be this or that and then charge $$$ for absolutely nothing.
Latest consensus is that warming up an EFI engine on "cold start" cycle for more than a minute is not best practice. Like I would say to my better half: keep the revs up leaving home and the engine will warm up quicker. Cold engines use more fuel as the "cold start" cycle runs the fuel system for rich mixtures. O2 sensor mainly influences the ECU outputs during idle and when cruising at constant rpm.
Best of luck...
 

pixelord

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Yep.
That is the ECU "cold start" cycle and corresponds with the engine temperature sensor.
Tree cutter may be right too. The IACs do become clogged with varnish and gunk with time.
Some may speculate to say it's the temp sensor or O2 sensor or something else that is failing (who knows without testing?). If your intake air filter is to be replaced then it could improve things (perhaps marginally). If your car is parked outside overnight then move it to an enclosed space if possible. This will assist start up on cold days.
Perhaps changing components might not improve anything (especially when it warms up again in later seasons).
Have you checked for error codes to see if anything abnormal shows up (e.g. O2 sensor etc)? Usually a good starting point.
Could be nothing to be concerned about and might save you some money if there's no real issue. Some businesses like to say it could be this or that and then charge $$$ for absolutely nothing.
Latest consensus is that warming up an EFI engine on "cold start" cycle for more than a minute is not best practice. Like I would say to my better half: keep the revs up leaving home and the engine will warm up quicker. Cold engines use more fuel as the "cold start" cycle runs the fuel system for rich mixtures. O2 sensor mainly influences the ECU outputs during idle and when cruising at constant rpm.
Best of luck...
The car had a service few months ago, where the mechanic cleaned up the throttle body and changed the O2 sensor.
The problem that I am mentioning only happening for last 2/3 days as the temp dropped significantly.
 

billythakid

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Could just be the battery having a hissy at the cold chucking weird voltage into the sensors , get it load tested and clean up the terminals if their grotty
 

lout

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no, that is not normal
a fuel injected car should start and idle correctly immediately
using the diagnostic function on your dash
Hold mode and up then key on
Release buttons
then
Press Mode = Dash Part Number - e.g. 1731
Press Mode = Mode Switch Voltage - e.g. BV - - - 5.0
Press Mode = Battery Voltage - e.g. V 11.8
Press Mode = Petrol Sender Voltage - e.g. FUEL 02.6
Press Mode = LPG Sender Voltage - e.g. VL 5.0
Press Mode = Remaining Fuel - e.g. 38L
Press Mode = Instantaneous Fuel (Liters per Hour) - e.g. 12.8 L/H
Press Mode = Engine Coolant Temp - e.g. 63 C
Press Mode = Vehicle Speed - e.g. 45 KM/H
Press Mode = Tachometer - e.g. 2380
Press Mode = Park Lamps Switch - e.g. P OFF
Press Mode = Dash Trouble Codes - e.g. t 00 (Press up/down to scroll through any codes, these are not PCM, ABS, etc codes)
Press Mode = Dash Test - All gauges will move, lights will come on and buzzer will sound
grab a pen and paper and record your values
in the morning before starting engine, check the battery voltage should be a bit over 12v, check what temperature the ecu thinks it is, if it seems about right
then start engine and check instantaneous fuel use at idle, a cold engine at idle will be around 2 litres per hour, a fully warmed engine will be around 1.4 litres per hour
next day before bed disconnect battery for 5 minutes (you will need radio pin code), this will reset the ecu fuel trims
in the morning repeat the process and see if engine starts and idles better and compare notes to previous days start
fwiw, my daughters commodore, i swear she has it in gear before the ignition barrel had sprung back, and is driving within five seconds,
that's parked outside and 5am starts, my wife works afternoon shift and her commodore starts and idles immediately with no issues
the ice on the windscreen well that's another issue
 

Nut Kracker

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It could be the CTS.
You can check this by first, without starting the car and as Lout described above.
Press and hold the mode and up arrow buttons.
While doing this, turn the ignition to the 'ON' position (red lights on the dash). Do not start the car.
Release the buttons (audible beep will be heard).
Scroll to the engine coolant temperature, using up/down arrows.
The temperature displayed, should be +/- 5 degrees of the ambient engine temperature.
In other words, take off the radiator cap and whack a thermometer in there and compare the temperatures.

A failure in the engine coolant temperature sensor
circuit should set either a Diagnostic Trouble Code
(DTC) 14 or DTC 15. An intermittent open or a short
failure should set DTC 16.
Resistor/s fault in the PCM should set DTC 17.
 
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