37 replies to this topic

[Andy_VX]

Sorry Alex, didn't see your reply, that's very good of you thanks. Let me know your paypal address and i'll send you some dosh for postage. You still got my address? 

[chickendippers]

No problem at all mate, ping address your address when you can please. Don't worry about postage

[phippsy]

Hi Andy,

 

My car just failed its MOT due to high emissions. Did you find out what was causing your issue out of interest?

[Nev]

Hi Andy,

 

My car just failed its MOT due to high emissions. Did you find out what was causing your issue out of interest?

 

High emission of what, precisely? Bear in mind you may have failed on a different emission to the OP....
 

Edited by Nev, 16 July 2018 - 07:56 PM.

[fezzasus]

 

Hi Andy,

 

My car just failed its MOT due to high emissions. Did you find out what was causing your issue out of interest?

 

High emission of what, precisely? Bear in mind you may have failed on a different emission to the OP....
 

 

 

No need to be pedantic in this case, a standard 2 way catalyst converts both HC and CO into CO2 so you can't elucidate a failure mode by knowing if it's CO or HC. Either or both could mean the cat has failed, or some failure is leading to overfueling and overwhelming the catalytic converter 

[phippsy]

 

 

Hi Andy,

 

My car just failed its MOT due to high emissions. Did you find out what was causing your issue out of interest?

 

High emission of what, precisely? Bear in mind you may have failed on a different emission to the OP....
 

 

 

No need to be pedantic in this case, a standard 2 way catalyst converts both HC and CO into CO2 so you can't elucidate a failure mode by knowing if it's CO or HC. Either or both could mean the cat has failed, or some failure is leading to overfueling and overwhelming the catalytic converter 

 

 

Cheers Fezz,

 

Im currently still on the Dutch base map so im guessing that may have something to do with overfueling
 

[CHILL Gone DUTCH]

It won't be to do with the map
AS THAt only gets used on high loads

On low loads it used the lambdas

So could be CAT
Or lambdas

[phippsy]

It won't be to do with the map
AS THAt only gets used on high loads

On low loads it used the lambdas

So could be CAT
Or lambdas

Could it possibly be an exhaust leak? Sounds like a pita whatever it is.

Fail was 'exhaust lambda reading after 2nd fast idle outside specified limits 8.2.1.2©

Max 1.030

Mine was 1.049 & 1.043

🙁

[CHILL Gone DUTCH]

Yes

[phippsy]

👍

[Exmantaa]

If you have OBD, make a log from the O2 sensor signals. (warm engine)

[Andy_VX]

Please excuse my ignorance but i'm trying to learn more about open / closed loop to diagnose the emissions fault on my VX. I' took it to a garage this morning and they've informed me that there's no reading from the pre-cat sensor 1 lambda (I replaced this with a genuine new Bosch one) so I assume the guy that mapped it has by-passed this for some reason, what would be the benefit of doing this?

 

My understanding of the system:

 

Closed loop should operate when the engine is at idle or at a constant cruising speed, this is when the ECU is taking an actual reading from lambda’s as to the AFR and adjusting as necessary.

 

Open loop is the state where the engine is under heavy load (acceleration) or when the engine is under no load (overrun). In this open loop state the engine by-passes the lambda sensors and enriches the mixture or weakens it depending on throttle position.

 

If a mapper was to by-pass the closed loop the engine would inherently run much richer at idle as it wouldn’t know what the AFR was and would enrich the mixture automatically, does that sound about right?

 

[siztenboots]

sensor 1 is the main fuelling sensor , if you have 0 volts then its gone very lean or loom failure

[Nev]

 

Please excuse my ignorance but i'm trying to learn more about open / closed loop to diagnose the emissions fault on my VX. I' took it to a garage this morning and they've informed me that there's no reading from the pre-cat sensor 1 lambda (I replaced this with a genuine new Bosch one) so I assume the guy that mapped it has by-passed this for some reason, what would be the benefit of doing this?

 

My understanding of the system:

 

Closed loop should operate when the engine is at idle or at a constant cruising speed, this is when the ECU is taking an actual reading from lambda’s as to the AFR and adjusting as necessary.

 

Open loop is the state where the engine is under heavy load (acceleration) or when the engine is under no load (overrun). In this open loop state the engine by-passes the lambda sensors and enriches the mixture or weakens it depending on throttle position.

 

If a mapper was to by-pass the closed loop the engine would inherently run much richer at idle as it wouldn’t know what the AFR was and would enrich the mixture automatically, does that sound about right?

 

 

Why not ring your mapper up and ask him directly, better than us guessing what he might or might not have done.

Edited by Nev, 26 February 2019 - 10:54 AM.

[Andy_VX]

Yes I have spoken with the mapper, he's been very helpful but i'm just trying to get an understanding of how it works for my own piece of mind. 

 

They've informed me that they do not disable O2 sensor during mapping and that it may be a loom issue. I need to find a wiring diagram now so i can check that, if anyone has one that would be much appreciated. 

[siztenboots]

if you are getting 0 volts , then I would check the grey plug on the loom , pin 6 for 12v supply , the plug is between both lambda plugs on the loom 

[Andy_VX]

if you are getting 0 volts , then I would check the grey plug on the loom , pin 6 for 12v supply , the plug is between both lambda plugs on the loom 

 

Excellent, thanks very much i'll check that tonight. 

[siztenboots]

picture to help find it , pin 6 is the red-white 2.5mm thick wire , its common to both lambda and few others