Cold Start Issues After New Spark Plugs

S

STIBungy

Member
Location
Denver, CO
Car
2007 FX35 AWD
Hey all,

I changed my spark plugs last night and now I'm having trouble starting it when cold.

The plugs that went in are NGK Iridium LFR5AIX-11. I've searched the forums and looks like some are pionting to a battery problem but mine is less than a year old and I havent had any issues starting until I changed the plugs.

Help?
 
It'll start but stumbles a bit before it smoothens out. Then everything runs fine. No stumbles or hesitation.

Iridiums come pregapped.

I just disconnected the battery to reset the ecu. I'll find out tomorrow morning if the ecu reset helps.
 
I had the same problem when I changed a few spark plugs over the years. My problem was that I left a hose or connector unplug or had a spark plug that was gap too wide. It is always good to check to make sure that everything is reconnected and the hoses are tight. I would recheck everything, especially the coil pack connectors and spark plug gaps, even if they are pregapped:wink:
 
The ecu reset did the trick. Fired right up this morning with no hesitation.

I didnt realize the ecu was this finicky.

Thanks everyone for input and suggestions.
 
I used the same plugs on mine. This is off-topic - One thing that I didn't realize when I bought those plugs is that they are only 60k mile plugs vs. the 100k Platinum ones. I always had thought that Iridium was supposed to last longer, but I did tons of research and ultimately concluded that I was incorrect. Refer to this thread, specifically post 6: https://www.infinitiscene.com/searc...s-NGK-LASER-PLATINUM-OEM-Cost-Mpg-performance
 
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I'm not sure I'd let the platinums run 100k. When I pulled the old plugs out, I saw that they were the OEM platinums. At 113k miles, they looked very worn. I compared the gaps visually and noticed that the platinums were worn to the point the gap difference was noticeable between the new and old plugs. I should've taken a pic of both side by side.

On another note, I noticed 2 of the cylinders on the driver's side were leaking oil from the valve cover into the plug holes *(@&!^#%!!! Guess that'll be something to take care of down the road.
 
To fix the leak you'll need a valve cover, a valve cover gasket, and about 4 -5 hours. Many had this problem.
 
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