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The mkiv Supra Owners Club

Idling/lambda issue


Steviekid

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Well that's my brakes finished so on to the idle...

 

Over a year ago my car was doing this at warm idle (usually when the car had been restarted while still warm). I changed the idle air control valve which made no difference. When it was at the garage for it's mot (Feb 08) they ran a diagnostic and found the O2 sensor wasn't showing up so they replaced it with a new universal one. The car seemed absolutely fine for a couple of weeks but then it started again and progressively got worse until it began running poorly at low revs. There was also a smell of fuel when the windows were open. I barely used the car for the rest of the year due to various reasons so never got round to looking at it till now.

 

I checked the voltage between OX1 and earth and didn't get a reading at all so I removed the sensor and it looked like this:

 

image

 

I let it soak overnight and cleaned it up this morning. Now it's back in the idle seems to be fine but the voltage over OX1 to earth when warm is all over the place reading anything between 0.25 and 0.85 volts. Am I right in assuming the state of the sensor is more likely an effect of another problem rather than the cause? The car's literally only done around 500 miles with it in. If so what should I be looking at?

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Lambda voltage of 0.25 and 0.85 volts.is about right, as the switch point is 0.45V,does it rhythmically go back and forth?

I had a slightly bad idle, but managed to cure it by adjusting my wide bands simulated narrow band output.

 

Yeah, it goes back and forth. I was under the impression is should be between 0.5 and 0.7V though?

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Yeah, it goes back and forth. I was under the impression is should be between 0.5 and 0.7V though?

 

No as the switch point on all narrow band lambdas is 0.45V.

Should be fine if it does it with a regular rhythm, as it switches.

Nothing wrong with universal ones, as long as you buy the right type.

Edited by Tricky-Ricky (see edit history)
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