[elantraelite]

Hi all,

Earlier this year my 09 Diesel wagon starting running rough on a cold start.

I have noticed this winter that it wasn't running rough on older days any less than 14-15 degrees it was fine.

Now that the weather is starting to warm up. Today for example was 19 degrees and it started rough with a rough idle, blew a bit of smoke and then was ok.

Low compression? Leaking injectors? Faulty sensor??

Car doesn't burn a single drop if oil.

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[cruiserfied]

Sounds like typical glow plugs, except that it's not happening on cold days?????

[elantraelite]

Does the MAF sensor have much  to do with start up? Any other sensors that might be faulty? There is no fault codes eoither

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[Asterix]

The coolant temperature sensor will let ECU know how much fuel to add on cold start... Could be dodgy or bad connection..

Don't know if it's possible to read resistance in the sensor, but my guess would be that unplugged the ecu will get "cold" info...

[constipated]

Does the MAF sensor have much  to do with start up? Any other sensors that might be faulty? There is no fault codes eoither

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I had MAF sensor issues causing rough start and blowing smoke. Went away when Hyundai replaced it.

Isn't cold air denser with more oxygen so could explain why it's not happening on cold mornings.