Denso Iridium ITV20TT spark plugs

[ibcrusn]

While changing plugs back to NGK's I was shocked to see the tips of the Denso ITV20TT plugs when removed. One had the iridium electrode almost completely gone and a .042" gap. The other three had the electrodes in place but the iridium tip fell off when placed on my toolbox. I haven't checked the mileage they've been in for but will tonight.

The gist of the post, if you're running the stock heat range Denso Iridium TT plugs it would be a good idea to pull them to inspect and check the gap.

***Edit...just checked my logbook and the plugs had just over 16k miles in them. Other than the last tune I worked with David and one autocross event I haven't been hard on them at all.

As an OEM replacement for the average Joe user these should have lasted a lot longer than 16k miles. Be aware if you're in the market for stock heat range plugs...avoid these for now.

 

[Redline]

Some people don't care either way, but my tuner swears by NGK IXs. He's had instances where bits of the Densos have broken off and fallen into the cylinder; said he'd never run them again.

 

[ibcrusn]

I'm certain the plug that was .042" when removed lost the iridium tip in the cylinder, not a pleasant thought.

Don't get me wrong Denso makes some good plugs but I will avoid the TT series of iridium plugs going forward.

 

[neganox]

This isn't the only platform I've heard of the porcelain cracking and falling off on Densos.

 

[ibcrusn]

The porcelain was fine, the tip of the center electrode was gone on one and fell off on the third when I put down on the tool box. If you're able to zoom in on th epic you can see the tip on the 2nd and 4th (.027 & .026), however on the 1st and 3rd the small tip is missing opening the gap up to .042". Denso advertises them as having a .4 mm iridium center electrode and a .7 mm ground electrode.

I'm just throwing it out there because the #1 plug was .042 when removed so the small iridium tip had to of come off inside the cylinder.

http://densott.com