I searched and all I find are threads about correct gap, I'm in a different situation.

Today I started to switch out my spark plugs and upon removing one I noticed the gap was huge. It is definitely larger than the 0.031 that the FSM calls for, my gap gauge didnt even go high enough to measure the exact gap. My 4Runner has always seemed to run fine so I replaced the old plug with a new one (NGK V power 0.031 gap) and drove it around and didnt notice any problems. The gap in the old one is very large, large enough for me to stop replacing the rest of the plugs for now.

Rig is a 91 4Runner V6 3.0

My first question is should there be any reason my old plugs have such a large gap? The old ones looked like fairly new NGK's that dont really need to be replaced, but now I'm concerned with the gap on them. The current plugs were in it when I purchased the rig so I wasnt sure what shape they would be in.

My second question is would there be any reason to replace all of them with correctly gapped plugs at this point? The runner has ran fine as far as I could tell. Would the large gap have adverse affects on anything like gas mileage?

I'm just confused

 

improper gap can cause poor mileage, a miss, poor sluggish acceleration. Maybe the p.o. misread the plug gap. Do it right and have a peace of mind.

 

As the plugs wear-out the gap gets bigger and bigger so my guess is they were worn-out. I changed the plugs in my old 95 Taurus last year and they must have been the original plugs because they had about an 80-90 thou gap.

 

I learn something new every time I get on this forum! I will finish replacing the rest of the plugs today.

Thanks guys

 

Plus if you let the gap get too far for too long, you run the risk of damage to the coil and ignition system. It takes a lot of energy to get a spark to jump a larger distance, after a while of your coil having to produce at near peak it will overheat and fail.

 

I'm new to the 4runner, and I've had it only about three weeks. It was running smooth, and the power seemed fine. It did fail smog recently by a very small margin (for high "NO"). While checking stuff, I pulled one plug (the previous owner had installed the NGK specified in the FSM). It was gapped at .042! The others were anywhere between .036-.042. Just wanted to comment (and remind any noob's to check their plug gaps) on almost any vehicle I guess, as soon as they buy a car!

 

this is why when you get a new car you do a tune up

 

10x on the new car tune-up requirement......my bad: Wife's truck, she was noticing some "missing" upon acceleration..... 2 weeks later, it was much worse. Read all about possible leaking head gaskets online, got REAL worried, checked plugs, this is what I found. Changed out with NGK plugs, properly gapped (see difference), truck runs like new, SO much more power and accel response. Can't wait to see improvement in mileage .