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Discussion Starter · #1 ·
Hey there, lads. In the last 3 days I notice something strange. It happens only on the 1st start of the day. The engine cranks, but is reluctant to start. it does start eventually, but it takes 4-5 seconds to do so and the 1st 1 or 2 seconds it runs rough. Afterwards it is all smooth. If I turn off and on the car after that, it starts immediately. All the consequent starts for the day afterwards are normal. There are no error codes recorded, the car runs well, the battery connections are OK. They were lose and that caused some issues with the key fob not being detected always, but not it was sorted by chance. The battery itself is in its 3rd year and is most probably on its way. I will try to find my tool for measuring the voltage of the battery and test this, but do you guys recon I should have anything else checked as well?
 

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Alfa 159 2.0 JTDm Lusso 6sp.
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As a pure guess based on that I would say fuel pump getting tired and taking too long to pressurise on the first start.
 

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Discussion Starter · #3 ·
As a pure guess based on that I would say fuel pump getting tired and taking too long to pressurize on the first start.
I will check the pressure via diagnostics tomorrow on cold start, but I do not have any of the other common symptoms of failing Fuel pump ' no loss of power, no sputtering, nor stalling. But, if it is just failing to build up pressure on time on 1st start, than might just be that the battery is going out and the cold cranking amperage is now just not high enough...
 

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If cold cranking amperage was insufficient the starter would turn the engine slowly or else just make clicking noises as the solenoid wouldn't be engaging?
 

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Discussion Starter · #5 ·
A quick update. New battery is in and the issue persists. It manifests itself only if one starts the engine after a couple of hours after switching it off. On hot engine it starts without hesitation. Cold start however requires several seconds of cranking to turn the engine on. If I interrupt and take the fob out and put it back in again, it also starts immediately. Fuel pressure seems to build up quickly enough to 8 bar. I am puzzled.
 

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I have had a similar problem, not with starting from cold, it starts first time every time. It is the idle and slight hesitation up to 2000 rpm for the first minute of so. I looked at all old posts and created a few new ones.

You could consider temp sensor, located near the dipstick they only cost about £10 and:

Throttle body

MAF [you can test this by starting from cold with the MAF disconnected to see if it improves / starts]

Injectors

Plugs

Vacuum leak inlet side

Carbon build up valves and or soot on O2 sensors

Fuel pressure / fuel pump

And this list goes on. The only things I have not tried are throttle body and fuel pump / pressure but as its perfect when warm after 2 mins I haven't tried them.

Let us know how you get on

Nick
 

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A quick update. New battery is in and the issue persists. It manifests itself only if one starts the engine after a couple of hours after switching it off. On hot engine it starts without hesitation. Cold start however requires several seconds of cranking to turn the engine on. If I interrupt and take the fob out and put it back in again, it also starts immediately. Fuel pressure seems to build up quickly enough to 8 bar. I am puzzled.
Have you tried pulling the choke out?
😶
 

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Discussion Starter · #9 ·
Plugs are on circa 10 k km, Bosch, coils are ok,only one was faulty and that cylinder misfired, so I changed it. Throttle body was taken off and cleaned last summer, did a carbon clean too. Inlet gaskets were done along with the rocker cover ones. idle is stable, car runs well, besides this annoying issue on cold start,which manifested itself just a couple of days ago. I am worried that it could f up the starter motor eventually, so I want it taken care of.Annd besides that, being an OCD, it bothers me on a special level.
 

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I am the same. I am faced with the only option of taking to a specialist! I have a pretty advanced scanner / diagnostic and can record live data which might show something but unless you know expected values how would you interpret anything. I too have an OCD and am frustrated by 2 mins of cold running!!!!
 

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Maybe my choke joke has some merit.
If it's a cold start problem only, that could point to fuel / air mixture.
Bad sensor reading causing bad ecu adjustments?
Which sensor if that's the case, I really don't know.
 

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Good idea, however you pose the right question, which sensor?

Does anyone know which sensor most influencing air fuel mixture on start up?

Thanks

Nick
 

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I know from previous experience that the coolant temperature sensor has a lot of influence on the startup mixture; being that the coolant gets up to temp which therefore means the engine is up to temp as well. My old Polo wouldn't start when cold, but after about 5 minutes would start up but be incredibly rich until it warmed up properly.
 

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Good idea, however you pose the right question, which sensor?

Does anyone know which sensor most influencing air fuel mixture on start up?

Thanks

Nick
Intake Air temperature sensor
Coolant Temperature sensor

The only other sensors are
Camshaft position sensors
Rpm - TDC /Crankshaft position sensor - dodgy signal/sensor on this wont allow car to start.
Detonation sensors
Fuel Pressure sensor
Absolute pressure sesnor
Oil level/Temp sensor - This is not wired to the ECU
Oil Pressure sensor.
 

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Its definitely not the MAF. I bought a new one and there was no change. I seem to have replaced everything apart from the throttle body and fuel pressure sensor which I am guessing is integrated?

Thanks

Nick
 

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Nope fuel pressure sensor located on fuel rail. rear one from memory ..you must have disconnected the wiring when you did the injectors. Can test this through diagnostics since the ECU gives a calculated value to compare to measured value(what the sensor outputs). If values differ greatly you'll first have to determine if the sensor is bad by tapping into the fuel rail with a gauge.
 

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Discussion Starter · #20 · (Edited)
today I tested it with MAF unplugged and checked all the fuses and it started ok. Plugged the maf and retested and it again started ok. Will see if this reoccurs at some point. The air intake temp sensor should not be the issue,hence if malfunctioning it adopts -45 degrees C as default temp.
 
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