Denso Spark Plug Model

stick to the sc20hr11

 

I just recently changed my plugs to Denso IXEH20TT. They work pretty good. Engine runs smoother.

 

you got lucky/
that's not what's recommended/

 

Thanks for that, I corrected my typo above. I checked my receipt again and it was the IXEH20TT that I ordered for the 2010.

 

SC20HR11

 

SC20HR11 is the old model plug. IXEH20TT is Denso's new model with finer twin tip electrodes that are supposed to improve ignition. Time will tell if the finer tip plug lasts as long.

 

I read a thread where there was some debate if the IXEH20TT was the right part for the 3rd gen. I know the SC20HR11 works for sure so I went with that one.

 

I put the TTs in my 2011 and no issues. Manufacturer's of parts like spark plugs will sometimes make "improvements" in their products. Sometimes they work better than the OEM parts, and sometimes not. Just because there is an improved version of the same part does not mean it is the wrong part for the car. Even if it does work better, the auto manufacturer is not going to bother to update the owner's manual to reflect it.

 

http://densoautoparts.com/

 

I'm finding a lot of dead links, either looking around at above link, or googling "denso find my parts"

 

I'd recommend the Denso Twin Tip IXEH20TT. My car has 169K miles. I switched to the TT just before my current tank of gas, and my car has never had such good gas mileage. I'm working on a possible 650+ mile tank (56.5 mpg on the trip odometer in 463 miles so far with mostly 10 mile or less trips). Today's drive was 39 miles each way, mostly cruise control 56 mph, cross/head wind out, and cross/tailwind back with an average of 61mpg on the dash.

Spark plugs are probably not the only factor in my good gas mileage this tank. I cleaned the EGR cooler to like-new condition, cleaned oil out of the intake manifold, just before this current tank.

Luscious Garage installed Denso SC20HR11s at 151K miles right after I bought the car at 150K miles. I started getting a misfire two months ago. By this time I was doing more things DIY. Experimenting, I found that the misfire followed the spark plug switch to the different cylinder when I switched them, so I swapped them all out for the Twin Tips, since the labor was more effort than the cost ($30 for all 4).

As a note, both the 17k mile SC20HR11s and the new Twin Tips had gaps that were under the 1.0 to 1.1 mm spec (ranging from 0.9x low mm - don't remember off hand - to 0.975 mm) . I've read here that either: 1) it's not recommended to adjust the gap to avoid potentially damaging the tips, 2) adjust the tips, or 3) the Densos have smaller than spec gaps on purpose due to the Twin Tips or other reasoning. These are not all compatible reasons. Apparently Luscious Garage didn't do any adjustments when they did the initial spark plug change for me. I chose to carefully increase the gap my new Twin Tips to 1.0 mm. I didn't cause any damage doing so.

As for why one of my SC20HR11s failed after only 17K miles, I think either it was a dud, or maybe they got contaminated due to burning oil that was coming through the PCV system into the intake. They don't look bad to me, but testing connectivity and resistance with a multimeter, they are have enough barely visible stuff on them to make those readings inconsistent.

 

I have a '10 PriusV and have talked to three nearby Toyota dealers now who all say they use the Denso SC16HR11 plugs. The manual calls for the SC20HR11 and none could tell me why the change - "That's just what we've been doing." Toyota may have issued some sort of bulletin suggesting the change because Denso says the SC16HR11 burn one step hotter than the SC20HR11 plugs. So there is a difference, but both will work and fit I've been told. I'm still not sure on the advantages of a slightly hotter spark plug.

 

I have a '10 Prius V and have talked with three area Toyota dealers all saying they use the Denso SC16HR11 plugs when replacing now. Denso says the SC16HR11 burn slightly hotter than the SC20HR11 and Toyota likely issued some bulletin recommending the change, at least in the US(?) I don't know for sure though since Toyota themselves couldn't seem to answer this question when I called Toyota N. America.

 

I've talked with three different dealership service dept's who have all said they now replace use the SC16HR11 plugs so I don't know what the difference or purpose might be for that. Denso says the SC16HR11 burns a little hotter than the SC20HR11.

 

Replacing the stock spark plugs with another make or brand, depends on the electrode gap on your recommended spec. If you've got different brands, not necessarily denso, it would work fine. Ensure the electrode gap is within spec