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Discussion Starter #1
Ok I have a question regarding the acutal plug gap for the tundra V8.

I bought replacement plugs from the dealer (Denso K20R-U) and I asked if they were pre gapped. He said yes. I went home to install them and of course the first one out of the box was cracked, it was too late to go back and exchange them so I decided to wait till the next day. While I had the plug there in my hand, I decided to verify it's gap. The plug right out of the box measures .027 The Tundra owners manual calls for a .031 gap.

So, the next day I went back to the dealer, since I had to return the cracked one anyway, I decided to double check on this "pre-gapped" plug. Again, I asked if these plugs were pre gapped and what the gap is supposed to be. The guy said yes they are ready to be installed as they are pre gapped (he didn't have the gap specs there and he told me if I wanted that information to talk to someone in service). I then asked if there were any other Toyota models that called for this same plug and he said yes! So I looked into it and about 5 or so other Toyota vehicles use this plug and the gap ranges go from .031 - .044 So what gives?

I asked in the service department to see what they had to say and one of the service writers flagged down a tech and asked him. He told me that all Toyota plugs are pre-gapped and ready to be installed. He even told me that that's how they do it, the techs just install them right out of the box!

So what gives here? Should I just install them out of the box? The manual and various websites state the gap to be .031 not .027 there is a clear difference in these gaps here.

I know too much gap is just as bad as too little gap.

Thanks,
-Mike

Moderators Note: The thread "Spark Plug Gap Discrepancy" has been moved to the Engine and Drivetrain Forum for better exposure and replies. PM was sent to thread starter of its relocation. --- Possum
 

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I always pre gap mine because the factory settings in my opinion aren’t very accurate. I used to be a tech too!
 

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It is 0.031 gap. If your doing it yourself, go buy a gapper for a dollar at the auto store and double check it yourself before installing. Sometimes while going through shipping, the cases of plugs are being moved around and tossed, maybe causing the tip to be bent just a hair enough to throw it out of range. Just check it yourself before installing. It only takes 2 seconds of your time just to be safe.
 

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bkoneski47 What happened to you I thought you were going to the Dyno run (PM me)?

Yes the gap is .031” it’s in the owners manual.
 

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Discussion Starter #5
bkoneski47,

I do have a gapper, that's how I discovered the difference. As for them getting bent during shipping, there is no way they are all bent wrong. I could see 1 or 2 but I checked every one of them. Plus they come with a plastic sleeve covering the bottom to protect the gap.

I would be curious to see if anyone out there recently had a tune up at Toyota and had plugs installed. If so pull out one of your plugs and measure the gap. Because if everyone here is telling me to set the gap up to .031 than Toyota not only installs the plugs with the incorrect gap in Tundra vehicles but about 5 other models too. Some of the gaps in these other vehicles call for a .044 gap! So WTF?


-Mike
 

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Mike I just bought some Denso plugs from the dealer and they were pre-gapped to .031" Only one was out of spec.
 

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I picked up a set of the Denso Iridiums this afternoon. They were indeed all pre-gapped -- just to the wrong distance! Every plug was set to 0.041-0.042", so I did have to fix them to the 0.031 they should be for this application.

They still would have worked at 0.041, but I'm a purist and want everything perfect. So, that means to the thousandth of an inch for me.
 

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Mike, I had a similar situation but installed them anyway. I had a noticeable loss of power. I waited for the ECU to relearn the timing but it never did feel right. I had to pull them and regap to the manual's specs before the engine felt like its old self again. This was a couple years ago, so I don't remember what the gap was. I would check each plug and set it to the manual's specs. It will save you time and trouble.
 

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i’m having the same results but the plugs i replaced were in really bad shape the gap was huge due to wear, the pre gapped plugs i bought were all .041-2 so i adjusted them down to .031 and now i’ve lost considerable power, i figured the same, that the comp would adjust, but it hasn’t so now i’m considering re gapping the plugs back to .041 & see if it makes a difference
 
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