Slow Ignition Solution?

[BlackWorksInc]

Factory replacement recommendations for 2003-2009 4Runners are 120k for Iridium Spark Plugs used in the 2UZ-FE and 30k for the Standard Resistor style plugs used in the single VVTi 1GR-FE engines. Some older Tundra and Sequoia used standard plugs, but by about 2002~2003, all 2UZ-FEs should have been specc'd for Iridiums.

You can run plugs longer, but that doesn't mean it's recommended or that they are working efficiently. I've seen people run 1GR-FE engines into the 120k range on factory plugs. But I've also seen plenty of misfire, failed coils, poor idle, intermittent issues because of that. Keep in mind that the factory gap is supposed to be something like .040", that doesn't mean that the ignition coil can't fire the plug if it's .050", but it means that the coil has to work harder and likely won't be as hot or strong as factory specification.

 

[sport2004]

Factory replacement recommendations for 2003-2009 4Runners are 120k for Iridium Spark Plugs used in the 2UZ-FE and 30k for the Standard Resistor style plugs used in the single VVTi 1GR-FE engines. Some older Tundra and Sequoia used standard plugs, but by about 2002~2003, all 2UZ-FEs should have been specc'd for Iridiums.

You can run plugs longer, but that doesn't mean it's recommended or that they are working efficiently. I've seen people run 1GR-FE engines into the 120k range on factory plugs. But I've also seen plenty of misfire, failed coils, poor idle, intermittent issues because of that. Keep in mind that the factory gap is supposed to be something like .040", that doesn't mean that the ignition coil can't fire the plug if it's .050", but it means that the coil has to work harder and likely won't be as hot or strong as factory specification.

Thank you for this, adds much more perspective. Much appreciated.

 

[ArthurKotb]

I have a 2004 V8 and replaced my OEM plugs at 98,000 miles with iridium plugs, Denso SK20R11. I went to Advance Auto at 60,000 and was advised to wait until I was at 100,000 since they were iridium.

My owners manual says to use only iridium plugs and not to gap them.
However the specifications section says .043" is the gap.
Replacement: 60,000 miles or 72 months
V8 Denso SK20R11, NGK IFR6A11
V6 Denso K20HR-U11. NGK LFR6C11

So bad advice from Advance Auto. I'll be replacing the plugs pronto. I tow a 23' aluminum travel trailer of about 6,000 lbs. and my 17' bass boat, about 2,000 lbs. I've not had any issues with idling or acceleration. gas mileage remains the same, in town or on the highway.

I have been told that the spark will most certainly make the necessary arc to ignite the fuel mixture but idle can suffer and the engine may even stall when slowing to a stop. I've not had that experience.

 

[sport2004]

I have a 2004 V8 and replaced my OEM plugs at 98,000 miles with iridium plugs, Denso SK20R11. I went to Advance Auto at 60,000 and was advised to wait until I was at 100,000 since they were iridium.

My owners manual says to use only iridium plugs and not to gap them.
However the specifications section says .043" is the gap.
Replacement: 60,000 miles or 72 months
V8 Denso SK20R11, NGK IFR6A11
V6 Denso K20HR-U11. NGK LFR6C11

So bad advice from Advance Auto. I'll be replacing the plugs pronto. I tow a 23' aluminum travel trailer of about 6,000 lbs. and my 17' bass boat, about 2,000 lbs. I've not had any issues with idling or acceleration. gas mileage remains the same, in town or on the highway.

I have been told that the spark will most certainly make the necessary arc to ignite the fuel mixture but idle can suffer and the engine may even stall when slowing to a stop. I've not had that experience.

Thanks for this input. Looks to me like you're doing the right thing.

 

[ArthurKotb]

From the NGK site:

"Traditional Single Iridium Plugs Denso's Iridium Power and NGK's Iridium IX series have iridium fine-wire center electrodes with tranditional nickel ground electrodes. The ground electrode will wear out first. Typically we have found you can expect 50-80k miles on a traditional iridium plug. But plug manufacturers have to temper their projections as driving conditions and motor modifications differ. Additionally, because gradual wear will "round-off" firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. Therefore, NGK gives them a life expectancy of 40-50k miles and Denso assigns a recommended replacement interval of 30k miles."

 

[sport2004]

From the NGK site:

"Traditional Single Iridium Plugs Denso's Iridium Power and NGK's Iridium IX series have iridium fine-wire center electrodes with tranditional nickel ground electrodes. The ground electrode will wear out first. Typically we have found you can expect 50-80k miles on a traditional iridium plug. But plug manufacturers have to temper their projections as driving conditions and motor modifications differ. Additionally, because gradual wear will "round-off" firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. Therefore, NGK gives them a life expectancy of 40-50k miles and Denso assigns a recommended replacement interval of 30k miles."

Interesting, and thoroughly confusing...LOL

 

[ArthurKotb]

Interesting, and thoroughly confusing...LOL

Totally confusing, especially since my T4R came with Denso plugs and I can't find the NGK plugs. I'll follow the manual and get the Denso plugs, change at 60,000 going forward. YMMV

 

[AuSeeker]

From the NGK site:

"Traditional Single Iridium Plugs Denso's Iridium Power and NGK's Iridium IX series have iridium fine-wire center electrodes with tranditional nickel ground electrodes. The ground electrode will wear out first. Typically we have found you can expect 50-80k miles on a traditional iridium plug. But plug manufacturers have to temper their projections as driving conditions and motor modifications differ. Additionally, because gradual wear will "round-off" firing points over time, the concentrated firing power and voltage requirement benefits will be reduced. Therefore, NGK gives them a life expectancy of 40-50k miles and Denso assigns a recommended replacement interval of 30k miles."

Interesting, and thoroughly confusing...LOL

Totally confusing, especially since my T4R came with Denso plugs and I can't find the NGK plugs. I'll follow the manual and get the Denso plugs, change at 60,000 going forward. YMMV

Just an FYI, any manufacturer is going to "underestimate" the life of their product so they aren't held responsible for premature failure, both NGK and Denso long life versions of the iridium plugs will easily last 60,000 or more miles.

 

[sport2004]

Thanks, Skip...

Not to be cynical, but could also enhance sale volumes.

 

[BlackWorksInc]

I wonder why the difference in recommendations? I would imagine if Toyota thought the Iridiums couldn't last 120k, they wouldn't recommend it. i.e. the direct injection engines recommend 60k intervals on their plugs.

 

[ArthurKotb]

I had the original SK20R11 plugs in my 2004 V8 T4R for 98,000 miles and it performed just fine. The owners manual says 60,000 but the parts guy said iridium plugs are good for 100,000. I had a long trip coming up and I didn't want to take any chances so I changed them at 98,000

I went to a Denso Products site (not Denso) and they say the iridium long-life plugs are good for 120,000 miles. The Denso TT (twin tip) are good for 100,000 miles and the iridium power plugs are good for 30,000.

At the Denso site they say the plug models beginning with “S”, “Z”, “F”, “D”, and “V” are Long-Life plugs are are good for 100,00 km, not miles. Mine is the SK20R11 model so it appears I'm good for 60,000 miles. [100,000 km = 62,137 miles]

The owners manual says 60,000 miles or 72 months then 120,000 or 144 months. It's been 60 months but only 34,00 since the 1st change at 98,000 / 14 years. (Yes, 14 years or 168 months. I bought my T4R as my retirement vehicle so I drove it about once a week to work, 48 miles round trip, if there wasn't any snow/ice/salt until I retired in 2013. There was the occasional fishing trip as well.)

I already ordered new plugs and I'm at 132,000 miles right now. I may pull a plug and see what it looks like. Since it will be 60 months next month, I'll probably change them, getting back on track for time instead of mileage.