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Hello all - I had an account on here a few years ago but was deployed for some time and I believe the forum deleted my account :frown. Okay now to the problem...

BLUF: My FJ has a very rough idle, either in park or drive, but when stopped.

Backstory: I replaced my plugs with Denso Iridium's. I went through each one very carefully. Additionally I just installed a AIRAID CAI. I thoroughly cleaned the MAF, etc. I also unplugged the battery upon installation. This is really puzzling me because I am pretty good when it comes to mechanical work, but I have gone through everything at least three times and still no luck. Also, for some reason the vehicle seems to be running lean....

Any ideas/suggestions on what could be happening?
 

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Disconnect the battery for 15 minutes? Lets the ECU recalibrate.
 

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I disconnected the battery when I first installed everything and I also disconnected it yesterday to reset the ECU; but still not progress.
 

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Wouldn't hurt to clean the throttle body as well if it's not the plugs....

If you have any account issues or simply want to change your username just fire me a pm and I'll see what I can do.

:cheers:
 
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I switched to all NGK Iridium in my 2007 with no problems at all, never tried Denso ones though.
 

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If you have problems after you worked on it and you've triple checked the things you did start looking for something where you were working(knocked of vacuum hose, loose or disconnected sensor connector, etc...). By the way do you have a check engine light on?
 

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I looked over all of the hoses; I'm going to disconnect all of the connectors to the coils and make sure they're snug. I do not have a check engine light on either. I checked the OBD II to double check if it was throwing any preliminary codes but it came up negative...
 

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I put fancy iridium plugs in my 07 and it ran like crap. I put stock plugs back in and it ran fine. Also did you happen to make sure all your plug wires are plugged back into the coil packs? ( Listen for the click ) I left one off my wifes corolla and it idled like hell. I found the wire and plugged it all the way back in and it idled smoothly :) Hope this helps
 
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Hello all - I had an account on here a few years ago but was deployed for some time and I believe the forum deleted my account :frown. Okay now to the problem...

BLUF: My FJ has a very rough idle, either in park or drive, but when stopped.

Backstory: I replaced my plugs with Denso Iridium's. I went through each one very carefully. Additionally I just installed a AIRAID CAI. I thoroughly cleaned the MAF, etc. I also unplugged the battery upon installation. This is really puzzling me because I am pretty good when it comes to mechanical work, but I have gone through everything at least three times and still no luck. Also, for some reason the vehicle seems to be running lean....

Any ideas/suggestions on what could be happening?
I have no extra advice beyond what everyone else has shared, but I appreciate the BLUF! Gotta love putting that bottom line up front!

Sent from my SM-G930V using Tapatalk
 

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As others mentioned, the early FJ's 07-09 do not run will with any of the fancy plugs.

Good ol' copper core plugs:

NGK LFR6C11
Denso K20HR-U11
 

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So directly after replacing the plugs it runs badly? I think its the plugs. I've read a few reports of the fancier plugs causing issues in the pre 2010 FJC's. That's why I replaced mine with the regular Denso's. What year is your FJ?
I switched to all NGK Iridium in my 2007 with no problems at all, never tried Denso ones though.
As others mentioned, the early FJ's 07-09 do not run will with any of the fancy plugs.

Good ol' copper core plugs:

NGK LFR6C11
Denso K20HR-U11
I replaced the plugs in my 07 with Iridiums with no issues... You can mess up the tip on an Iridium if you don't use the right type of tool for gapping, etc.
 

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What did you gap the plugs at?

All the coil packs securely reconnected?
 
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You could try reinstalling the old plugs see if symptoms change. May save you from unnecessarily buying new plugs.
 

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Discussion Starter #20
Update status: I went and purchased the OEM DENSO copper plugs; set the gap at exactly 0.043 (as per the owner's manual). Cranked the engine and after a few tries she started up. Smoothest idle since I purchased the FJ from the factor. The acceleration is back! Thank you all again. Next install this week/weekend will be a new exhaust system...
 
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