MR2 Owners Club

Hi I wonder if any one can help I’ve owned my MR2 for a few years now I noticed when I brought it that the manifold lambda sensor wire was melted/cut. The car ran fine without it so I left it. But I’m now trying to sort the car out and get everything back as it should be. The problem I am facing now is I have found two connectors in that area one connector has one wire to it and the other has 2 wires to it. I assume that one of the connectors use to go to the a/c compressor and the other to the lambda. Also apparently I have been told the car is a rev 2 that’s been converted to the rev 3 so now I’m not sure what lambda sensor I’m supposed to have and how many wires it’s supposed to have. Any info would be much appreciated ps pls see attached photos

Sorry photos to large

Photo

What are the wire colours to the plugs?

Hold on I’ll go find out

Looks to be brown with red tracer and brown with green tracer on th 2 wire plug and black on the one wire plug cheers chris

Not the best picture

According to the 1991 diagrams the O2 sensor has 4 wires, the only thing I can see in the engine area with a single black is the knock sensor. Haven't managed to teack down the b/r & b/g wires ...... Yet

From 1989 - 1993 89465-29355 single wire.

From 1993 onwards 89465-29805 4 wirres

There should be 4 plugs..intercooller fan,EGT sensor Aircon pump,O2 sensor.

Strictly speaking the early MR2 uses a 2 wire sensor.

Toyota made the mistake of not running an earth wire to the sensor but relied on the earth through the body of the sensor which works perfectly when the car is new, however over time due to rust goes either very high resistance or open circuit. You can almost get away with it as the O2 Sensor is a very high impedance source and there is next to zero current flow from it, however I sorted out the poor earth when I put in the stainless downpipe and ran an earth strap from it to the block.

MR2DI4 wrote: ↑04/05/21 1:38 Strictly speaking the early MR2 uses a 2 wire sensor.

Technically speaking early version of 3sgte had 1 wire sensor and single pin electrical connector.Don't know where you've got your info from..

like I said you will find that the 1 wire sensors quickly changed to a 2 wire because using the case as the earth was a bad idea. Yes it's a 1 wire sensor but it doesn't work if the earth is no good. There is no such thing in electronics as something with 1 wire that works you need a circuit so really it's a 2 wire. Pretty sure later sensors included a separate earth wire for good reason.

MR2DI4 wrote: ↑08/05/21 5:29 like I said you will find that the 1 wire sensors quickly changed to a 2 wire because using the case as the earth was a bad idea. Yes it's a 1 wire sensor but it doesn't work if the earth is no good. There is no such thing in electronics as something with 1 wire that works you need a circuit so really it's a 2 wire. Pretty sure later sensors included a separate earth wire for good reason.

Are you talking about the same wire as the knock sensor wire? Shielded wire? Put it simply..if you going to the car parts shop and you'll be asked single pin or 2 pin electrical connector or 3 pin or 4 etc..you'll be given the part based on your replay! In your case you'll be given 2 pin lambda sensor instead of 1 pin which you are Not be able to use.