Carbon Build up - RH Manifold

[andy-w]

Last night when i removed the precats i noticed the LH manifold was virtually clean inside but the RH one had a very heavy carbon build up.
Best way to describe it is like toner from a laser printer.

I could understand if it was the LH manifold as that lambda sensor has not been replaced but the one on the RH is approx 1k miles old.

Other than that the car is running fine and there is no smoke comming out the back.
Also the compression on all cylinders is approximately the same.

Any ideas of where to start looking would be a great help.

Cheers

Andy

[GreenV8S]

I suspect this is a legacy of running with the old knackered sensor, before you replaced it.

[andy-w]

Would make sense...i gave it a good clean out (as best i could) so i shall do another 500 - 1000 miles and see what it is like then and compare the two!!!

Like i say its running fine...better in fact with the precats removed...!!!

Cheers

[Griffter]

Does the ecu on cat cars adjust the mixture differently for each bank then?

[andy-w]

Would have thought so as you have two lambda sensors monitoring gasses etc...?

[GreenV8S]

Would be worth sticking an analog multimeter on the back of the lambdas and see what the readings are like. If they're both showing the normal cyclic readings then there isn't much wrong. Otherwise there might be a sensor or installation fault. For example if you get the wiring crossed up both banks will head to the opposite ends of the lambda scale.