replacing oxygen sensor 1 on 1999 3.4l prado

[Lammy Lurker Find all posts View Profile Close Lammy]

Bought a used 1999 3.4l gxl 90 series two years ago. Car's exhaust releases strong unburnt petrol smell. also fuel consumption is not good, ranging from 16-18 litres per 100 km for suburb driving. Car has travelled 189,000 km. My mechanic thinks its the oxygen sensor not working well , even though the check engine warning light is not on. Bought an after market RAE oxygen sensor from Repco. Problem is my mechanic just could not find the old sensor. He could not even locate the catalytic converter (the sensor is supposed to be located between the manifold and the catalytic converter ). Any advice or comments please.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

These models don't have a cat or O2 sensor. As they were in the light commercial range they were not required. Easiest way to check is to have a look at the diagnostic plug in the engine bay... right hand side of motor beside the intake. There will be a pin marked for O2 sensor... see if there is a metal terminal inside it or not. I've only seen 2000 onwards have them.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

Btw 16-18 per 100 for suburban driving is not great but also fairly consistent with a lot of others. I went through similar issues and have improved mine with things such as an injector overhaul, knock sensor harness repair, power valve removal from first muffler and also timing belt change.

[Darran K Member Find all posts View Profile Close Darran K]

Yep what RanJ said.

[Walky88 Member Find all posts View Profile Close Walky88]

Im going through this with mine at the moment.... chugging the fuel and very gutless while driving.

Have replaced all timing belt and componenets, replaced all filters, air flow meter. Next is a brand new exhaust from pacemaker (headers to tailpipe) and going to do the injectors and have a look at knock sensor wiring harness while im there!

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

I wouldn't stress about the exhaust too much. Get the car back to what it should be then do all that. The biggest issue I found with mine was that the old timing belt had jumped two cogs on one of the cams...

Also check the condition of the spark plugs and make sure it has twin electrodes in there. Toyota specify them for an even burn in the chamber. Another thing I've done was service the auto...

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Sparks in good condition is definetly important but dual electrodes don't specifically provide a better burn. The spark can only jump from one electrode at a time (the nearest one). As they wear the one which is nearest will change back and forth, providing a longer life. Dual electrodes were created to increase life, before we had newer tech like iridium plugs.

[juc33_prado Advanced Member Find all posts View Profile Close juc33_prado]

Check MAF sensor.

Samuel