Rough Idle After Plug Change
01-16-2019, 10:09 AM
#1
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Thread Starter
Rough Idle After Plug Change
2015 C2S 16,300 mi. I DIY'd the 4-yr/40,000 Service 1. Used Bosch spec plugs from Pelican. After the change the idle is different/slightly rough. It immediately stops with accelerator input. Additionally, good strong, steady pull throughout RPM range -- accelerated quickly to just over 6K RPM, no codes thrown -- different fact set from what I've seen from a forum search.
Anyone else experience this? Is this in the realm of normal or a symptom of something I should address?
Thanks. Duke
Anyone else experience this? Is this in the realm of normal or a symptom of something I should address?
Thanks. Duke
Last edited by Duke I; 01-16-2019 at 07:56 PM. Reason: Info add
01-16-2019, 01:32 PM
#2
It is likely you are noticing something that was there before as you focused on this after service.
However if the idle is truly out of spec first thing to check would be air leaks behind MAF (hoses, intake gasket, ECT). If you are sure something happened after plug change then you can do new plugs and coils.
However if the idle is truly out of spec first thing to check would be air leaks behind MAF (hoses, intake gasket, ECT). If you are sure something happened after plug change then you can do new plugs and coils.
01-16-2019, 03:56 PM
#3
Rennlist Member
If it continues I would pull the plugs and take a look at the gap and then go through the process again. All tight/torqued correctly, coils seated, electrical connectors all "clicked" and then did you do anything else during your maintenance activity...... air filters? etc.....
Just go back over what was done and double check.
Just go back over what was done and double check.
01-16-2019, 05:41 PM
#4
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Thread Starter
Plugs came pre-gapped, of course. Will do the recheck. Good suggestion -- I'll just have to limber up for the plug-by-plug contortions!
Did change out the air filters and oil & filter at the same time. Thanks. D
Did change out the air filters and oil & filter at the same time. Thanks. D
01-16-2019, 05:44 PM
#5
Rennlist Member
If you don't have engine codes it's probably fine. I wouldn't be concerned. Your ECU will let you know if there is something that is out of spec on the ignition. The sensors are ULTRA sensitive to this stuff.
01-16-2019, 06:00 PM
#6
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Is it possible you are noticing the rougher "normal" idle because you are paying more attention ? When warm, I find my idle in normal mode lumpy because it's a tad low. If I put it in sports mode, it climbs by 100 rpm or so and is super smooth... In normal mode I can see the empty passenger seat back shake slightly, it's gone in sports mode. Another reason to drive in sports or + ;-)
01-16-2019, 06:53 PM
#7
You might clean your throttle body they can get a bit grimy/oily
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01-16-2019, 07:55 PM
#8
Rennlist Member
Highly doubt that the new plugs are the cause. You would see a misfire code pop up. Virtually any ignition related issue would throw a code. Could your gas be the culprit?
01-16-2019, 08:05 PM
#9
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Thread Starter
I'll see if toggling between sports and non-sports mode makes a difference.
Thanks. D
01-16-2019, 08:08 PM
#10
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Damaged coil pack?
Or an un-seated coil pack??
Or an un-seated coil pack??
01-16-2019, 09:46 PM
#11
Rennlist Member
I changed the plugs on my pickup truck a couple of months ago and one of the pre-gapped plugs had been pressed in to about half of the recommended gap during presumably rough shipping&handling and had to be bent back out. Not sure that is what's happened here, but it definitely can happen.