Hard start issue when cold?

[neemo6]

This started couple weeks ago and has been getting progressively worse, to where I have to sit im my car a few minutes before i can drive it. It takes multiple crank attempts for it to fire up, then when it does it runs rough and dies out. I'll have to restart it a few times and let it 'warm' up a bit. Once it I get it going it drive fine as if nothing was the issue, also if turn it off and the car sits for a couple hours i can go and start it up as if no issue. Its only when it sits for longer than say 2-3hrs that it has this issue. I have ran codes on vag-com and came back with (dont remember exact codes as they're in my laptop at home): coolant temp sensor (G83) at radiator (low signal or something like that), lean fuel bank, and o2 sensor (dont recall which one). I have replaced the coolant temp sensor, but still have the issue. I just ordered a fuel filter as this is what im leaning the issue might be, but I also dont want to be throwing money at the problem. Any ideas as to what to look for or how to better diagnose my issue?

[frogspit]

I’m guessing the fuel pump. Do you hear it prime when the key is turned to the on position?


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[neemo6]

Yes, it sounds like its priming.

[EuroxS4]

I had similar symptoms before my starter died.It would crank longer than normal and eventually start.After a few months starter died.

[neemo6]

I had similar symptoms before my starter died.It would crank longer than normal and eventually start.After a few months starter died.

Would it run rough then die after initial startup?

[old guy]

What exactly was your cooling system DTC? An issue with the rear CTS can cause problems with a cold start. Do your cooling fans run immediately on start up?

[EuroxS4]

Would it run rough then die after initial startup?

it would idle barely and sputter out shortly. But as other have mentioned could be a number of things.

[neemo6]

What exactly was your cooling system DTC? An issue with the rear CTS can cause problems with a cold start. Do your cooling fans run immediately on start up?

17698 - coolant temp sensor at radiator outlet (G83): signal too small
P1290 - 002 - lower limit exceeded - intermittent.

the fans do not come on right away.

[old guy]

If the ECU thinks the engine is hotter than it really is you will have cold start issues. Once the engine is warm the starting issues go away. I would recommend that you do some logging of your temperature sensors to see if one of them is out of whack. The rear CTS is what determines the cold start fueling requirements. Here is some information on what to log. Clicky click® Be sure to scroll down and read post #22 as well.

[neemo6]

-Update: Just replaced the fuel filter, it got a tiny bit better as it took less cranks this time to get it to start. Still ran a bit rough till it warmed up.

If the ECU thinks the engine is hotter than it really is you will have cold start issues. Once the engine is warm the starting issues go away. I would recommend that you do some logging of your temperature sensors to see if one of them is out of whack. The rear CTS is what determines the cold start fueling requirements. Here is some information on what to log. Clicky click® Be sure to scroll down and read post #22 as well.

Thanks I will try that today!