Hello there Yotatech. Decided to replace the O2 sensor in my 86 4Runner to try curing the poor fuel mileage I've been getting recently. Bought a Denso 234-1056, which is specified as the correct part number for a 86 22RE 4Runner in the Denso catalog. Removed what appears to be a Bosch sensor from the manifold, and it looked slightly smashed on the tip. Sure enough, the hole in the manifold isn't deep enough for the Denso sensor to drop in completely and thus the flange doesn't seat fully. I would estimate about 1/8th inch or a hair more from being flush. Looks to be the stock manifold as far as I can tell. Anyone run into this problem before?

 

 

The one on the right is correct and OE spec. Post a pic of your manifold.

 

With the thickness of the Toyota Gasket it should take up your 1/8" length.

If for some reason your O2 bung is no longer factory thickness 2 gaskets should take care of your problem.

Pictures would be a big help!!

 

Sorry, haven't had a chance to take any more pictures, but looking at the parts catalogue, it looks like my exhaust manifold is from a 22R, based on the shape of the manifold, flange to the 2-1 collector. I went to NAPA to look at the correct O2 sensor for that application, a Denso 234-1051, but the sensor itself is the same, just a shorter wire... I'm stumped, the only other thing I can think of is that its maybe a later model manifold, with the 4 wire sensor...

 

I converted from a single wire to four wire sensor and I still don't think there was a difference in depth.

Every exhaust shop has weld on bungs for these O2 sensors. I would just get one of them and use it as a spacer - put a gasket on both sides.

I still can't figure out why you're having this issue, but this should put the issue behind you. I do have an 22RE OE manifold if you want a replacement.

 

Awesome! I'll send you a PM!