Live data question. Suspected lambda issue, poor fuel consumption

[98cliosport]

Hi,
After many searches I have find lambdas seem to cause all sorts of issues but unable to find the information I'm after.
Basically my girlfriend has a 182 and she's complaining of a fairly sudden drop in fuel consumption and down to below 30s. It used to be pretty good, above 30s.
I connected OBD2 and read the pre and post cat voltages.
The upstream voltage seems to be switching quickly and ok however the downstream voltage does not switch at all and stays at about 450mV.
I've read the downstream(post) cat doesn't do much but I assume it should still be switching and providing information right? Does anyone know if the after cat lambda sensor controls fuel mixture and effects fuel consumption?
I'm just wondering if I should change one to start with?
Theres no fault codes just no switching of the after cat voltage.

Thanks for your help

 

[Lagerlout]

Here's mine. Post-cat lambda just checks cat afaik. Doesn't switch lean/rich.

 

[98cliosport]

Nice one, mines pretty much the same then. Any idea on why fuel consumption would increase so suddenly? Might go for a front lambda just to try it out maybe?

Thanks

 

[Fastchip]

You probably want to look at the "long term fuel trim" parameter.

Replace Front lambda Sensor if;
- it gives a fault code, DUH..
- long term fuel trim is way below or above 128

 

[98cliosport]

No fault codes found, only reading close to that was idle rich apadtive which was 138.
My computer hasnt got fuel trim
Shes saying its low on power now. No misfirr, but its got the normal lumpy idle. Well i assume uts normal cos its always bern like that lol

 

[98cliosport]

what should map readings be on live readings? Thanks

 

[smiler_]

If long term fuel trim is way below or above 128

What figures would you say are way above and below? And if the long term is not 128, is it an indication that it's going down hill (mines 122)?

Cheers

 

[Fastchip]

122 is fine, as long as its not your girlfriends age...

 

[smiler_]

I think I'm all right then...! Cheers Henk

 

[smiler_]

Hi Henk,

My long term trim is down to 116 now... at what figure do I need to be thinking of getting it sorted out?

Cheers

 

[ripp]

just bought my rs tuner and before unlocking it I wanted to plug it in to see how it works. but when I click on the live data button the rs tuner shuts down with an error - rs tuner has encountered a problem and needs to close..
any thoughts on this?

 

[Fastchip]

Have you updated to the last RST software version 4.27 ?
Please send us email info@fastchip.nl

 

[ripp]

yes I made the update. it works now after I selected only about 15 parameters to be shown. I also encountered some problems when connecting to the ecu ("connection to the ECU could not been established" or smth like that) but after a system reboot this issue went away.
Henk, you will receive an email when I will request my unlock code along with the cal and rst files