[golfergavnz]

My i30 diesel has trouble starting on cold
And when it does it idles rough for awhile then settles
While at the same time blows a cloud of greyish smoke that's quite a strong diesel smell doesn't smell like oil

The things I've done so far to try and fix
1) replaced all glow plugs myself(quite an easy job )
2) replaced the battery although it showed s full charge it's cca was showing only 300 it should have been 600

This has improved the car but it stills plays up
Every 3 or 4 start from cold

Any help would be greatly appreciated

[Shambles]

Are you waiting for the glowplug indicator light to extinguish before cranking?

[elantraelite]

Maybe check to make sure each glow plug is actually heating up.

I had the same issue and changing the glow plugs stopped the smoke on start up.

The rough start continued for a little and has now pretty much gone.

[eye30]

Have you recently changed your fuel supplier?

[BC]

I've have a similar problem and was advised by the local Hy dealer it may be a blocked EGR valve.
(I haven't replaced the glow plugs so not sure if this would fix it)

[Phil №❶]

There's a fuse for the glowplugs, is it functional 

[golfergavnz]

Hi yes I definitely wait till the light goes out
I think maybe I should just point out again from my original post I have replaced all the glow plugs and replaced the battery it has made it a lot better but now and then it does the usual rough start and blowing smoke out the exhaust it's never a problem when the engine is warm

[Phil №❶]

Check fuseable link.

Glow plug relay & fuse.

Check 12v supplied to the glow plugs.

Diagram

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[constipated]

Same problem. Hyundai said a code pointed to mass airflow meter/sensor. Replaced under warranty and the smoke and rough idling is gone.

[bryanj86]

My i30 has had smoke on start up during winter (mild southern Queensland winters) since near day 1 buying the car new in 2011. I haven't bother too much about it. I have told the dealership and they kept the car for a night and of course it wouldn't replicate the issue. I wouldn't worry about it too much.... ?

[Phil №❶]

If the smoke is light in colour, you need to have the glow plug circuit checked. Do not touch the accelerator when cranking the motor. Always wait for the glow plug light to extinguish, before cranking the motor.