[notadealer]

Hi all

I have a MY12 SX CW CRDi auto that's intermittently running rough. I first noticed it only when climbing hills at low speed and acceleration, so I figured it was the transmission changing a bit too eagerly, before the revs are really up. I granny-drive, and I'd seen comments from people that the i30 does this sometimes.

Now I'm sometimes seeing similar seeming behaviour even at 90km/h on the freeway - it'll stutter and run a bit rough for a second, then be back to normal. Especially on cruise control. Still under pretty low loads; it doesn't seem to happen when it's working hard, like climbing a hill at speed or accelerating into a slipway. But at times when it's nowhere near a gear transition.

It's now sometimes taking longer to start for the first time in a day, throwing traces of blueish smoke when it does so. It has a brand new battery due to a cell fault; it was starting slow before the battery change, and continues to do so afterwards.

It was serviced a few months ago and only does quite low kms, mostly freeway. It's just over 30,000 total.

Dealer didn't think anything of the occasional roughness and wrote it off as just the transmission being a bit eager changing gears when the revs aren't high enough.

Is this something to worry about in a "get it into a service center pronto" sense? Could it be poor quality fuel? (How does one even tell?). I'm looking for advice on things to try to eliminate possible explanations for the issue, things to try to change to see if it goes away, experiences of others with similar problems, etc.

Consumption remains good for a 4-speed auto (bah) at about 6.9 if I'm doing in-town driving with traffic lights etc, much less on highway cruise. It helps that Perth is dead flat and I never drive at peak hour. But anyway, no obvious consumption spike, in case that's relevant.

(I miss my manual Elantra, by the way; auto might be easier with a small child to worry about as well, but I'd much rather have more than the ability to give the transmission a gentle hint about the highest gear to choose).

[Phil №❶]

Hesitation in a Diesel is engine should never be ignored. I don't think the transmission is causing any problems.

Diesel uses compression to ignite the fuel air mix and is generally very reliable. Light smoke at start up is normally un-burned fuel and usually related to an injector problem.

You could possibly have picked up some water in your fuel which needs to be eliminated ASAP. Unlike a petrol engine, water in Diesel can destroy many components. The solution to this is either a tank & fuel line clean out $300 by Hyundai, or the addition of diesel additive in your fuel every tank. Try to buy fuel at busy servos that get fresh deliveries where possible.

Diesel additives are available at a car accessory stores.

Here is a link to the product I use

Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.

[notadealer]

Thanks for guidance, I appreciate it.

I'll bump up the service and take it in soon, and pop some fuel additive in in the mean time.