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The mkiv Supra Owners Club

MOT Hydrocarbons Fail


SimonR

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Emissions failure:

 

Hydrocarbons = 1,680 ppm (

Lambda = 1.04 (0.97-1.03 required)

 

I was under the impression that Hydrocarbons = unburned fuel. If that’s the case, why is 7 times the hydrocarbon limit only .01 above the required ARF (Lambda)?

 

Also, the AEM AFR gauge shows that AFRs are normal.

 

I flooded my engine badly a few weeks ago and I’ve read that this can fark the o2 sensor. Sound like a starting point?

 

No cat, but that hasn't been a problem before.

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  • 1 month later...

It’s a misfire on number 6 (found by unplugging the connector when idling – no change in engine note). I’ve swapped plugs with another cylinder (no change) and swapped the coil packs between 5 and 6 (no change). The resistance on the plug wires for number 6 is the same as for the other cylinders.

 

Having eliminated plug and coil pack, I’m guessing that it’s got to be either the signal to the coil pack or something horrible going on the chamber, but the plug looks ok.

 

Any more suggestions welcome please.

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  • 2 weeks later...

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