My 96 Tacoma 4x4 SR5 has high NOX gas and is running really rough. This engine doesn't have an EGR Valve. I want to replace the front O2 Sensor and Fuel Filter. I read here that often solves this problem. The fuel filter looks like a piece of cake, but I don't think I can do the front O2 Sensor. It's on top of the exhaust pipe at an angle. The catalytic converter and heat shield above it make it impossible to get in there from below, and I can't reach it from the side either.

I'm pretty sure I'll have to take it to a garage. Actually I'm not sure how they'll do it either. It looks to me like you have to remove the Catalytic Converter to get at it.

 

Never screwed with the O2 sensors on my truck, but they are a PIA in general. After the nightmare I went through with the rusted bolts, Id just take to a shop.

 

It may be possible to get at the bolts with a breaker bar, but they're at a weird angle, I don't know. Mine are probably seized up like yours too. Almost bought some Seafoam and a breaker bar, but decided not to. I'll probably end up taking it to a garage or Toyota dealer.

 

you can get in there with eye protection and some small wrenches

may need a chisel to chip off the old nuts if they are rusted badly

 

OK, maybe I can find a small 12 mm box wrench. I still don't know if there's enough space to get leverage on those bolts though. We'll see. Thanks guys.

Looks like this stubby box wrench might do the trick. http://p.ly/JlbyZ. In one tutorial I saw, the guy sprayed the bolts with penetrating lubricant for 3 days before attempting to remove them.

 

bring some baby vice grips in there with ya (#4 size) chances are the nuts are
rotted and between 10 and 11mm no longer 12mm

 

This. I used the a deep 1/4" drive 11mm socket and then maybe a 10mm, then sort of ripped the remaining rusty sleeves off with the mini Vise-Grips. The studs are a lot tougher than the nuts--I assume this is the plan.

 

My nuts aren't that rusted. I already tried fitting 10mm, 11mm and 12mm sockets over them and only the 12mm fit. I'm gonna get the baby vice grips though, and some Seafoam to (hopefully) keep them from breaking, if I can get them off at all. Maybe I'll try the 1/4" drive socket too.

 

Got a stubby ratchet, but it's just too tight up in there. I think I may unclip the O2 sensor wire and then try to take the whole section of exhaust pipe out. It's not that many bolts, but they're a little rusty. Some liquid wrench and a breaker bar might do the trick. Otherwise the shield above the catalytic converter and the gas or oil line are in the way too much.

 

Well, I had to drive the truck today. Yesterday I changed the radiator hoses on my "other" car ('98 Volvo S70 GLT), and ran out of coolant. Carquest is the only place that stocks Zerex G-05. These Volvos are picky, but I love 'em.

So anyway, if you pull this one vacuum line it runs well enough to drive. When you put it back on the engine idles way down, very restricted. On the way home I got a Check Engine light. Plugged in the Actron and it finally spit a code, P0510 Closed Throttle Position Switch.

When I started it up earlier I was actually thinking it might be some sort of electrical controller or solenoid issue, etc... as it was ramping up and down in a weird way. So obviously something is wrong with that Throttle Position Switch. Now I can do further research. Anyone familiar with this issue?

 

I just replaced the Throttle Position Sensor and it's running WAY better now! Guess the old one was indeed shot. A new one cost around $80 at Auto Zone.

Now I think maybe I'll replace the fuel filter. I'm not sure when it was last done, but for $20 it probably wouldn't hurt. At some point I'll remove and clean the Idle Air Control Valve too.