Lamda Sensor???

[chu346]

Lamda sensor! could this be causing me bad fuel economy.

I've had a superchip fitted for the last couple of months and just put the old one back in. The car seamed to be more economical till it seamed to have learned its settings. It worst than before now. I might aswell drive quickly a driving slowish doesn't help much!

Any ideas, I need to do something NOW!!!!!

My wallet can't take much more of this somebody help me

[MONSPORT42]

Hi Chu. Can't remember your set up. Are you saying you have a Lamda Sensor or think you need one. My experience was that my 2.7 was more economical than when it was (briefly) a 2.5 although I did do a lot of motorway way miles where the lower revs/higher torque work in our favour. Did you have a remap with the uni chip? and do you have MAF?
A lamda sensor would help with tuning at the lower rev range.

[Brianmoooore]

Very few UK E30s have a lambda sensor. If it has then it should be producing a square wave output on the black wire,amplitude of a bit under a volt, with a frequency of not more than 2Hz.
Frequency is more important than the voltage, and can be checked easily enough with a meter.
Wiring diagrams I have show an engine ECU warning light for lambda equiped cars, which comes on when an ECU upsetting fault is detected, but I have a feeling this isn't always fitted.
Most cars with a ECU fault sensing system, go into a limp mode when a fault is detected, and retard the ignition to protect the engine and cat.This would do your fuel consumption no favours at all.

[Dan318-is]

i thought that as long as a lambda sensor showed a reading between 0.1 and 1v it was working?? is that not accurate enough?

[Brianmoooore]

i thought that as long as a lambda sensor showed a reading between 0.1 and 1v it was working?? is that not accurate enough?

There's a lot of misconception about on how ordinary lambda sensors work. They do not give a measurement of air/fuel ratio.
They are simply oxygen sensors. No oxygen in exhaust gas - zero output, any oxygen in exhaust gas - 1 volt output.
The ECU gradually leans off the mixture untill all the oxygen is not consumed. When this exhaust gas reaches the lambda sensor, it produces an output that instructs the ECU to richen up the mixture. This results in all the oxygen being burnt ahain, so the lambda output returns to zero, and the ECU leans off the mixture again.
THis is all simplified a bit, but that's basically how it works.

[chu346]

Monsport i'm saying I have one and I think it's playing up (fitted as standard).

Brian, sorry to be a dumbass but how exactly do I check the lamda sensor? Do I need to be series or parallel with the black wire? Break it down for me. Please!

Most cars with a ECU fault sensing system, go into a limp mode when a fault is detected, and retard the ignition to protect the engine and cat.This would do your fuel consumption no favours at all.

Could the car be pinking (pre ignition, or what ever it is!) as it's and Eta engine (high comp).

I really need to sort it, i'm gettin 12.7mpg now