i30 Owners Club

THE GARAGE (SERVICE, MAINTENANCE & REPAIR) => DIESEL => Topic started by: dcraig on August 05, 2024, 08:56:05

Title: Is there anything else I should do to investigate rough idle on cold start?
Post by: dcraig on August 05, 2024, 08:56:05

Model
2014 GD 5 Door Hatch, Diesel 1.6 CRDi, Auto, Gray

Issue Background

On the first drive of the day, I get hit by rough idling problems on start up.
Specifically, RPM is steady for the first 5-10 seconds, but then fluctuates/bounces between 650-950 for 10-20 seconds, before leveling out steady somewhere around 800-850.
The issue does not occur during normal driving, only on the first drive of the day.

Checklist
Based on the research I've done on this forum and elsewhere, here's what I figured I'd need to go look at:

OBD2 Check - Complete, no issues
Check/clean throttle body
Check MAF sensor
Check/replace PCV Valve
Glow plugs

Any advice on other things to check for would be helpful. Car has done around 95k miles.

Title: Re: Is there anything else I should do to investigate rough idle on cold start?
Post by: I30 GD on August 05, 2024, 17:40:33

Mine used to do that for the first 20 seconds or so, it was the glow plugs, I tested them when removed and they were all dead.
Changing them is a pain with little access, especially number 4,if you do it yourself, make sure the engines warm, use plenty of wd40/gt85 and go slowly winding them back in slightly if they go stiff, 👍

Title: Re: Is there anything else I should do to investigate rough idle on cold start?
Post by: dcraig on August 06, 2024, 12:20:25

Thanks for the confirmation on the glow plugs, just watched a quick video and yeah they look not fun to access. Still it's about the challenge right!

I'll try to update this thread once I've finished my list, and if anybody has any other ideas in the meanwhile let me know.

Title: Re: Is there anything else I should do to investigate rough idle on cold start?
Post by: josh1990 on August 07, 2024, 21:22:34

For glow plugs, I've seen many posts about how hard they are. I've done mine recently and were surprised how easy they were in comparison to any other glow plug I've changed.

Watch this before starting
https://youtu.be/CpnBcRVAYRQ?si=pRVvSs7vH9-Rbewa (https://youtu.be/CpnBcRVAYRQ?si=pRVvSs7vH9-Rbewa)

Spray some penetrant the day before.

Warm your engine first.