Advice needed. 1998 Toyota Tacoma-spark plugs+

My 98 Tacoma, 209k miles) began knocking a bit and was hesitant on accelerating, so I decided to put in new spark plugs. I did not put in wires as my budget was zero. I opted for the Bosch irradiums. The guy at Advanced nAuto said they needed to be gapped at .040, and 3 were straight from the box. The other at .038, which I made to .040.
Don't know what I did wrong, but it began "coughing' after warming up and idling at redlights. Called Advanced and others with the question about Gap. Some said .032, others .040, others still, .044. with all saying the difference was because I swithced to Irridium.
I had to drive it that way a couple of days. Today, cold and windy, I pulled the plugs to recheck.
They don't look right. The center electrode on all 4 is just a pencil point. And there was oil on the back one. What's a poor boy to do?

 

Well, Toyotas historically don't like Bosch ignition products. And v6 tacos require dual electrode plugs.

Either a Denso 3194 or an

$6 NGK 3967 NGK Spark Plug Stock # 3967

NGK 3967 is what your truck should have.

Welcome to TW

 

If you have a 4cyl you want

Denso 3119 or NGK 2087

But it sounds like you may have another issue to be honest

 

Check your Owner's Manual.

It will specify which plugs you need and the correct gap.


The guys at Autozone insisted I needed iridiums for my '06 V6 4.0L. I was doubtful, so I checked the manual. Turns out, I only needed simple copper plugs with a SINGLE electrode with a 0.040" gap. Got all 6 at Toyota dealer for $32 with tax.

My point, know what you need before you go to a DIY auto store. The clerk only knows what is in the computer. Many times the "information" is marketing driven, may or may not be what is needed. No sense in coughing up more $$ than what you need.

 

Wow. Great response. I have the 4 cyl. and have decided to trash the iridiums and go back with OEM's. The manual only says to go with dual electrodes (or anything other than than OEM) if I had he 6 cyl. I will let you know soon. Damn little electrical connectors and CLIPS are a b***h aren't they.
Anyway, here are the iridiums after >200 miles. The Oems have got me cranking fine, fires right up. And as long as I give it a little gas, it seems to idle alright. But take my foot off the gas and the shaking commences until she bogs down roughly.
Just so everybody knows I got the NGK BKR5ES 2460 plugs. Think I'll call my mechanic tomorrow and just pay the bill.

 

The plugs look a bit dark for 200 miles, but it is hard to read the plugs. It depends on how you did the engine cut.

Anyhow, your idle issue is likely not related to the plugs. Many items can affect the idle. Sensors, MAF, throttle body, injectors.........

 

Are you sure the "coughing" isn't a misfire? Has the CEL come on at all during this poor running? Even briefly? You could have easily screwed up a plug wire during removal.

Alternatively, could you have forgotten to plug the MAF back in if you removed the intake plumbing (this would eventually trigger a CEL)? I don't think you have a vac leak because those plugs look sooty, like you're running rich, so it's probably a plug wire.

 

Also, what's that (red circle)? Is the insulator cracked? If not, why is it so dirty after only 200 miles?

 

The 3.4l V6 has a decal on the timing cover stating that dual electrode spark plugs are imperative. The standard plugs from the dealership work fine; don't need iridium or anything special.