Mapping Out Post Cat Lambda ??

[A3 T]

Hi guys

A while ago I had a few issues with my ECU and since then I've had an error complaining about the post cat lambda sensor (something about the voltage being too high).

I've changed the sensor multiple times but the error just comes back after the engine warms up.

There's a few posts on here where people have had the sensor mapped out and I was wondering if this is easy to do?


I can read /write the map easily enough with nefmoto, I just need to know what software is required to map it out?

Also if it can be mapped out with no issues, what is the purpose of it in the first place?

 

[Prawn]

as far as I know, the post cat sensor cannot be mapped out entirely.

When most people refer to 'mapping it out', what's actually being done, is the threshold value at which it'll throw a fault code or EML is raised, to allow you to run with no cat.

the post cat sensor is there as a cat check basicaly from what I understand, by checking pre and post cat emissions it can detect when the CAT is no longer working / failling.

Primary fuelling on a wideband car is done by the pre cat wideband sensor. Hence why you can 'map out' the post cat.

As far as I know though, even after altering the threshold value, the sensor still needs to be present and working.

 

[<tuffty/>]

You will need a mapping tool and the definitions to enable you to map stuff out... tuner pro or WinOLS... you will also need to get checksum plugins if using this software as flashing a map thats not been checksummed will result in an engine that won't start

Best bet is to get it coded out as part of a remap... this is common enough to do when going stage 2 as most are done to counter de-cats

<tuffty/>

 

[Prawn]

oi, PT, quit skim reading and answer my post too

Can you confirm or deny?

 

[Broken Byzan]

Depends how it's mapped out as to whether it needs to be in place or not. Most require a sensor plugged in to allow adaptions to work. It's definition depending as to whether mapper can do away with it totally

 

[<tuffty/>]

oi, PT, quit skim reading and answer my post too

Can you confirm or deny?

There is contradictory info about this... some have disconnected the rear sensor and coded out all the usual stuff and adaption/fuel trims stopped working (possibly part of the readiness tests)... not tried it myself as mines still plugged in...

There is info on s4wiki/tuning that has a list of the maps that should be looked at... suggests it can be mapped out and disconnected but this is on ME7.1 ECU's for S4's which are a mix of narrow band functioanlity but have wideband features such as EGT probes/strategies and VVT

<tuffty/>

 

[Broken Byzan]

Works on 7.5 IF you have correct definitions as it's a 1x1 iirc so needle and haystack spring to mind without

 

[dayofthejackal]

Read your map out and let me know the number (example: 06A906032HN 360646 0001) and I should be able to point you in the direction of what to change.

 

[aragorn]

It can be done, info is here:

Tuning - S4wiki

ESKONF is the bit thats usually missed, and without that you need to have a sensor plugged in.


ME7.5 as standard uses the rear O2 for fuelling corrections as well as the wideband.


Edit: Bear in mind the map addresses in that post are S4 specific, you'll need a definition file for your own ECU to find the correct maps, and ESKONF is often missing from definitions and can take a bit of searching. I was lucky and found the location on Nefmoto for ESKONF on my ECU. If your ECU is common you might get lucky too.

 

[dayofthejackal]

ESKONF Byte 3 (Start at 0) 00110000 to 11110000 Search for AA FF 00 30 FF F8 30 normally at 0x10C4F

 

[A3 T]

Thanks for ALL the replies

I'll investigate and post back what I find.