lazy lambda sensors

[Bluebottle]

Has anyone experienced both lambda sensors taking at least 10mins to warm up and work correctly?
They were both working fine a couple of weeks ago but I know since then the garage messed about with the sci loom (poor condition and previous sparky miss wired some of the sensor leads.
I can't believe that both sensors would simultaneously fail (ecumate is saying both faulty) so before I buy two new ones, any suggestions would very welcome.

[blitzracing]

yes - id guess you have lost the 12 volt feed to the heaters on the probes- check the red wire for 12 v when the engine is running. Its not live with just ignition however.

[spend]

blitzracing said:

yes - id guess you have lost the 12 volt feed to the heaters on the probes- check the red wire for 12 v when the engine is running. Its not live with just ignition however.

Check it at the fuel pump relay, thats easy to get at.. It's something like a white/orange, one output goes to teh fuel pump & the other to the lambdas off the twin make/break relay .

[Bluebottle]

Thanks chaps, knew I could rely on the PH collective

[Bluebottle]

Ok, just ran some tests.

white/orange wire at relay gets power during fuel pump priming and continuously when engine running.
Lambda are both getting +12V on the white and red wire.
Initial fire up lambdas control afr then after 30 sec Ecumate sees both sensors go lean and lock out lean, afr gauge reads off scale 16+ and the engine chokes up. There is also a significant drain on the battery with ignition off

As i said earlier the garage tried to improve the wirin loom by splicing in new wires in the engine bay but managed to miss wire some of the sensors (throttle pot wires reversed, and dizzie amp wires mixed up for example which MA and myself corrected for them, Lambdas were working at this point). They then got another sparky in as something was still not right that we had put down to a possible air leak.
So long story short, i suspect the lambda wiring is wrong, so would very much appreciate any continuity tests etc i can do to try

Edited by Bluebottle on Friday 11th July 01:52

[blitzracing]

Id do a DC check on the lambda output- black and white wires on a hot probe and see what you get- it should be 0 volts for lean, or about 1.2 volts for rich. If you short the heater to the lambda input (ie 12 volts into the ECU, it will) read as rich (255). If its 0 volts either its genuinely lean, or the probes are faulty. The heater supply is also used to provide a voltage for the lambda outputs, but you say thats OK. You can check to see if the probes are working by quickly clamping the fuel line where it leaves the fuel regulator to go back to the tank to raise the fuel pressure and see if you get a rich reading for a moment. Have a read here:

http://www.g33.co.uk/images/PDFS/14cux%20faulot%20...

Try simply unplugging the probes and see if the engine keeps running- it should, but the ECU will try and richen the mixture and then eventually throw a fault code after some minutes. If it dies without the probes connected, look else where for the leaning off issue, as the ECU no longer has mixture control to lean the mixture off. There appears to be a software oddity in the ECU (therefore ECUmate readings) If you measure the lambda voltages you can see them switching, but you dont see the lambda readings from the ECU for a longer period- not managed to suss that one yet.

Edited by blitzracing on Friday 11th July 12:41