1.33L (1NR-FE engine) current spark plug recommendation.

[Mooly]

I'm contemplating replacing the plugs on my 9yr old (58k miles) 2010 Auris that has the 1.33L engine with Stop/Start. The handbook lists Denso SC20HR11 as original fitment, however the Denso site indicates that these are now obsolete and replaced by SC16HR11. In the past there seems to have been a bit of confusion, however I have just found this which although relating to the Prius is still the same plug:

Source:

https://priuschat.com/threads/gen-3-prius-spark-plugs-superceded-with-hotter-plugs.169260/

Quote

Due to OE requirements DENSO has to change the heat range from 20 to 16. These connected applications are mainly Toyota engines. The OE car manufacturer has already switched to SC16HR11 for newly manufactured vehicles. The Aftermarket will follow this consequently.

The level of heat range is connected to low or high speed driving. The initial choice for the right heat range is a result of expectations towards average use of the engine. After a few years of experience with this engine, the manufacturer decided to lower the heat range.

So I wondered if this is still the current recommendation. 

  

[HS78]

Hi

I believe you are correct in that the 16's have superseded the 20's. Have you removed a spark plug from your car to check what the part number is currently? 

I replaced spark plugs on an avensis last year that I have now sold. The spark plug socket needed was a 14mm one which I had to buy. (standard plug sockets are often 16mm or 21mm). Good luck with your plug replacements. 

[Mooly]

Thanks 🙂 I haven't removed one as yet as the plan would have been to have a new set ready first... and yes I must check the long reach plug spanner I have is the correct size. Its a long long time since I last did a plug change. I've spotted these on sale from what appears to be a reputable UK supplier for just under £8.00 per plug.

Edit... and it seems they have only one in stock. Hmm. 

 

[HS78]

I had a quick look online (at a well known auction site) and saw a set of 4 for £29.99 and free delivery within a few days. I use a magnetic pick up tool to remove the plugs as they can be quite far down inside the cylinder head. Some spark plug sockets have a rubber suction grip inside which works ok too. 

[Konrad C]

I have always stuck with the Denso spark plugs - SC20HR11, for my Avensis Valvematic. Since they are Iridium, they were changed November 2015 and done only 28,000 miles, they should be fine for a while. My old Avensis used Iridium spark plugs for the leanburn engine. They had a harder life due to hotter temperatures, and firing twice as much as a standard engine (wasted spark). The recommended period was 6 years or 60,000 miles 
Here is my post back then 

 

I will research the Denso change of spec, and decide if I should buy a set of SC20HR11 now for future use. 

[TonyHSD]

The spark plugs question resolved, the one number replace the other so either of the above will do the job, nothing to worry to much. 

[Mooly]

Thanks for your thoughts on this folks.

As far as I can tell, the Denso change from SC20 to SC16 is going up one step to a hotter plug which should be less liable to foul under low rev conditions. Interestingly, the NGK recommendation for an equivalent to the original SC20's seems to be one step cooler. Talk about confusing.

What I'm really interested in is whether this change of spec is in relation to the weird issue that I've reported on here since owning the car from new, and that is that after anywhere from say 10 to 15 months of use there is suddenly a change in performance, its sudden but very subtle and manifests as a slight 'hunting' effect at constant high speed. The fix is just to reset the ECU (Battery disconnect) and only then do you realise how much better and responsive the performance is. 

 

[Mooly]

Having tried ordering from a few UK based suppliers and getting the 'in stock' status initially, it seemed that when ordering they had less than four. I bit the bullet and bought from Mr T. These are the later specced (hotter heat range) SC16HR11's, the originals were the SC20HR11's   

It must be 30 years since I last changed a set of plugs and tbh I wondered how hard these might be to remove, particularly as they had been in there for 9 years... well I needn't have worried, in fact I couldn't quite believe how 'untight' they were. All four loosened with almost no effort (the bolt securing each coil pack was much tighter to release).

Curiously a couple of the plugs had visibly 'wet' threads, as if a drop of light machine oil was present.

Refitting was easy and I used a torque wrench although unfortunately the lowest marked official setting on the wrench was still above the required figure. I tried the wrench in a vice to get a feel for the torque and then wound the dial below this figure by the appropriate amount and thought it 'felt right' and so I went with that. Recommended figure was 11 to 18 ft/lbs or 15 to 24.5 Nm. Minimum marked setting on my wrench was 28 Nm.

 

[Motheo]

My 2011 Auris 1.33 had denso Iridium spark plugs in and they were due for a change and I opted to replace them with NGK Iridium set as Toyota dealership wanted R1300 for a set and I only paid R600 for the NGK set from my local spares that shop and they have covered 30 000km to date with no issues at all.

Sent from my SM-A500F using Tapatalk

[Mooly]

Thanks Motheo, good to know your NGK's are performing well.