Problem or problem

[nakedguy]

Ok so my MIL light intermittently comes on. Usually during acceleration then drops off when you take the foot off the gas. Sometimes it's just after starting up for a few mins until warmed up. Straightvaway I thought it's got to be the lambda. I plugged in the laptop and the screen shows both lambdas ok but an afr fault. However when throttling, one of the lambda readings go up the scale to about 1.4, the other appears to fluctuate if move at all from 0 or 0.1. This can be seen on the realtime graph aswell.
I'm thinking it's got to be the lambda but was puzzled when the screen said lambda 1 and 2 ok but AFR fault. Any good advice appreciated before I go buying a new sensor.

Cheers

[fatjon]

It could be that the lambdas are both OK and are actually telling you the true state of the mixture. I would suggest swapping them over, it could be a throttle pot problem making one bank of 3 very lean. I'm assuming the S6 engine has 2 throttle banks with their own pots?

[SI-PEN]

Sounds to me that one or both of your throttle pots are out of range/tolerance when moving through the rev range. May only need an adjustment of a throttle pot or replacement...ten minute job, if you know what you're doing...

[SI-PEN]

OK, just noticed you have a speed six, I'm thinking you only have one bank and one throttle pot??

[nakedguy]

Thanks guys. I'm going to look up the throttle pot adjusting procedure on here and sort that before trying to get the lambdas out. I've been told they are a pain as the decat pipes will have to come off. I am a mechanical engineer by profession so confident I can resolve it without too much expense....famous last words

[Buffoon]

Would not think a throttle pot would give these symptoms. You don't adjust them as such, just adjust throttle spindle position. If one is faulty ECU reverts to other. Looks like a lambda from what you say but don't take my word for it.

Post on speed six forum and/or give the experts a ring, ie whoever your trusted garage might be.

[Quentin1]

Balancing the throttles should bring your engine back to good health. Although saying lamda 1 & 2 are OK I suppose, that the voltage of at least one is quite stationary, right? AND the adaptive readings of one bank would be quite high and different from the other.

I had the AFR fault because cylinder 5 was not getting enough air. A throttle balance corrected that fault.

Regards,
Björn.

[nakedguy]

trying a balance is the road i want to go down first but trying to find the instructions for the sp6 is like finding hens teeth.