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When I turn off the ignition, the engine stutters for 2 -3 three seconds.

I cleaned the EGR valve
Changed the sparks
Cleaned the air filter
Cleaned the VTEC solenoid
Cleaned the PCV valve
Change oil at recommended intervals
Use Shell gas
Checked grounding wires

I'm out of ideas

 
Rep Power: 519

Elaborate on this. More descriptive.




It takes time for the spinning parts of the engine to coast to a stop, especially if the idle speed is high.

Do you have the radiator fan hotwired to the ignition circuit?

 
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The idle speed is very low (car is completely warmed up). It still happens even when the car is cold.

I'm not sure about the rad fan. I've never modified anything to do with the rad fan.

The engine has the feeling of trying to start off on second gear.

 
Rep Power: 519

I still can't picture (in my head) what the car is doing. Description is still too vague.

Video?

 
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Alright, finally got the video uploaded, and I took a look at the spark plugs as well.
One of the spark plugs(#2 in photo attached) is oddly clean compared to the others, no?

Supposedly it means its running lean/too hot. (#23 on this link http://www.4secondsflat.com/plug_chart.html, would you agree?)

Anyone have this issue before? Am I looking into the wrong thing?

 
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Oh, and when I was removing the plugs, the #2 was very difficult to remove. I just found out that could be because the engine was still too warm to work on (but all the other plugs came out easily...).

I guess that's another reason to think that the #2 plug is running too hot.

Did everyone stick with NGK? I read in our user manual that Denso is also supported/recommended.

 
Rep Power: 519

I don't see any issue in the video , and yes I listened with halfway decent earphones in.

All engines take time to come to a halt after you shut the key off. Some take longer than others, and your engine appeared to be in fast idle mode, cold engine.



I can't tell much from just the pic of the plugs either, but here's what I gather: Too hot on #2 plug, and here's why:

You said it was difficult to remove.
I see that Carbon has built up in the threads, possibly from insufficient sealing (undertorqued/lack of gasket crush). That carbon will make a plug difficult to remove.

The undertorqued plug does not have proper contact with the threads in the head, and thus cannot shed its heat properly, therefore that loose plug runs hotter then the rest. This may explain why you say it is whiter and you interpret that as lean. It's probably not really lean.



The reading of the plugs usually only indicates the conditions when the engine was last shut off, unless there has been fouling. If the engine was cold, the plugs would have been dark due to rich running.


Yes, either NGK or DENSO plugs, both can be acceptable.

 
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Thanks for the feedback

I'll have to accept that the civic turns off like this now I guess (she's getting old )... It definitely wasn't like that before. My mechanic acknowledges that something seems a bit off, but I don't really want to pay them right now to try and diagnose something that's not throwing an ECL.

Any tips on how to clean up the carbon? I've read that I can use carb cleaner. But I'm guessing that's when the spark is installed. I need to clean the carb off the threads.

 
Rep Power: 519

Maybe you notice something in the car that I didn't notice or can't tell from the video.


Before when?
Is this a sudden, recent development?

High idle RPM will make it take longer to come to a halt than it would if the idle speed were low.
Laws of inertia.

Worn rings might have less drag on the cylinder walls than they did when new, that could be a factor in how long it takes to stop spinning.

How many miles are on the engine, maybe 200,000?

Small wire brush, carb cleaner? You don't have to get them spotless, just clean enough to thread all the way in easily.