37 replies to this topic

[Andy_VX]

Hi all,

 

I'm after some advice please my car recently failed its MOT in spectacular fashion thanks to crazy emission figures, see below. 

 

 

Since it's last MOT it has had the following work, LEH K06 Trubo, 630cc injectors and a 80mm MAF. After installing the parts I took the car to Rabbid Rempas who mapped the car accordingly. I've not changed anything on the exhaust side of things and never had any real issues with emissions prior to the new parts being installed. I've never actually found out what my exhaust is but I think it's one of the early 2.5" Powerflow systems, it's been fitted from new so is probably going on 12 / 13 years old now... 

 

My thoughts are that either the MAF was faulty and was therefore giving an inaccurate reading when the car was being mapped, one of the lambda sensors has failed but would expect this to throw an EML or perhaps the cat has failed on the exhaust. 

 

Any guidance will be appreciated as not sure on the best place to start. 

Edited by Andy_VX, 13 September 2017 - 08:35 AM.

[SteveA]

Best and cheapest (in relative terms) place to start would be to replace the Lambdas with new OEM ones. If they dont fix the problem you can always sell them on at a small loss. A lot of emissions issues tend to be faulty Lambdas.

[Johnboyhgt]

Lo9king at the CO readings your cat is not operating or is burnt out. Any faults in your engine management ? Sent from my SM-G903F using Tapatalk

[Arno]

Nearly 10% CO means it's running really pig-rich.. Definitely not going closed-loop for some reason.

 

It's probably at the moment runing closer to 11:1 AFR.

 

Fuel consumption must have gone up too and I'd say you're even at risk of bore-wash on these numbers at idle and likely part-load.

 

With a dead cat but running stochiometric you'd expect the CO to be in the 1 - 2% mark max.

 

Something definitely up here. Either something is not working anymore (lambda, MAF, etc.) or the mapper/tuner perhaps disabled closed-loop running and left it at that or never adjusted the idling parameters for the bigger injectors so it's now dumping in way too much fuel?

 

Getting an OBD scanner on it and some data should already give some info.

 

As it's so way off my suspicion would be a boo-boo on the mapper/tuner end not correctly setting the ECU up for the new fuel system..

 

Bye, Arno.

[CHILL Gone DUTCH]

Best and cheapest (in relative terms) place to start would be to replace the Lambdas with new OEM ones. If they dont fix the problem you can always sell them on at a small loss. A lot of emissions issues tend to be faulty Lambdas.

You should also ask rapid remaps on the there strattergy of remapping and what there actually doing ( little late now ) but it is possible there cheating sensors or even ignoring them in order to hit hp figures which most people just look at I've also heard mappers/people are literally just cloning maps from other cars and calling it there own ( this might not be the case for rapid ) They could also only have limited access to different items within the map which can compromise other things

[CHILL Gone DUTCH]

Adding fuel to a map is stratergy which can be used to control knock limit and added boost levels And cooling And if boost has been added without adequate cooling it could be running in to correction table and adding fuel ( or removing ignition ) These are things I would personally want to know before having a car remapped

Edited by CHILL Gone DUTCH, 13 September 2017 - 09:24 AM.

[Andy_VX]

Thanks for the replies so far, I'm quite confident in the mappers abilities and everything he was doing made sense to me at the time. 

 

Turbo is running at 10PSI, we weren't chasing figures so everything should be well within the operating range of the lambda's etc. so don't think there would be any need to "cheat sensors" or run it really rich deliberately. 

 

IAT were very good throughout and he commented that they were the some of the best he'd seen so no issue there either. 

 

My gut feeling is that the MAF wasn't giving an accurate reading at the time it was being mapped. 

Edited by Andy_VX, 13 September 2017 - 09:33 AM.

[Andy_VX]

Could someone explain to me in layman's terms what closed loop means please? 

[james_ly]

Is it possible the MOT guy has measured wrong?

[Exmantaa]

It's running 0.7 / 0.75 Lambda at idle, so that is around 10-11 Air fuel ratio where it should be 14.7 AFR... (Lambda 1.0)

First check is the primary lambda sensor.

Either that one is faulty, or it's not running (mapped) in closed loop (that means running with continuous lambda sensor feedback => Google it) at all. Which would be rather silly at idle... 

 

 

Edited by Exmantaa, 13 September 2017 - 09:50 AM.

[Andy_VX]

It's running 0.7 / 0.75 Lambda at idle, so that is around 10-11 Air fuel ratio where it should be 14.7 AFR... (Lambda 1.0)

First check is the primary lambda sensor.

Either that one is faulty, or it's not running (mapped) in closed loop (that means running with continuous lambda sensor feedback => Google it) at all. Which would be rather silly at idle... 

 

 

 

Okay thanks that's helpful. First thing i'll do is borrow the primary lambda sensor from another VX and see if that solves it. 

[CHILL Gone DUTCH]

Be careful after changing lambda for hot temperatures or even running in to knock by adjusting the when you don't know what the circumstances at the remapping stage I would have a polite discussion with mapper first

Edited by CHILL Gone DUTCH, 13 September 2017 - 10:28 AM.

[Andy_VX]

I have spoken to him Chill, he's basically said that he would've spotted if there was a failed MAF at the time as it would've been obvious. 

 

He seems pretty sure it's a lambda issue but has said to bring it in for a health check. trouble is i now can't drive it on the road which means getting a trailer, PITA! 

[CHILL Gone DUTCH]

Is he sure the lambda was correct when he mapped ? If so just change it and reset fuel trims

[Nev]

Andy, my strong advice (based on the terrible idle characteristics) is to replace Lambda sensor #1 (the one near the turbo). This costs maybe £50 and will be well worth it IMO. Easy to do as well (unless your username is P11COV !). Make sure you buy a genuine item (not a Chinese copy or somesuch as they are out of tollerance/spec even when new, and it's a critical sensor).

 

The lambdas have a really hard time in general and are one  of the most common reasons for VXTs to run badly in my 9 years of observation.

 

If you buy and fit it fast, you can go back to the MOT garage (legally) to get it re-tested to see if it's had a positive effect.

 

GL.

Edited by Nev, 13 September 2017 - 11:22 AM.

[chickendippers]

Any joy with checking the sensors over Opcom?

I may have a couple of used working lambdas kicking around here if you need one I can get one sent out tomorrow?

[Andy_VX]

Andy, my strong advice (based on the terrible idle characteristics) is to replace Lambda sensor #1 (the one near the turbo). This costs maybe £50 and will be well worth it IMO. Easy to do as well (unless your username is P11COV !). Make sure you buy a genuine item (not a Chinese copy or somesuch as they are out of tollerance/spec even when new, and it's a critical sensor).

 

The lambdas have a really hard time in general and are one  of the most common reasons for VXTs to run badly in my 9 years of observation.

 

If you buy and fit it fast, you can go back to the MOT garage (legally) to get it re-tested to see if it's had a positive effect.

 

GL.

 

Cheers Nev, unfortunately I've been so busy with work and the weather has been crap so I've missed the opportunity of a free re-test. I will get a lambda sensor and get another test booked in though. 

 

Any joy with checking the sensors over Opcom?

I may have a couple of used working lambdas kicking around here if you need one I can get one sent out tomorrow?

 

Not yet mate, my old man has an OBD reader but his mate has it atm so waiting for it to come back! Cheers for the offer i'll let you know if i need a sensor.

Edited by Andy_VX, 13 September 2017 - 11:33 AM.

[chickendippers]

If you've missed the free re-test, find a friendlier MOT tester  

I don't want anything for the sensor btw, you're welcome to it

[Nev]

 

I don't want anything for the sensor btw, you're welcome to it

 

Very generous of you Dipper  

[chickendippers]

 

 

I don't want anything for the sensor btw, you're welcome to it

 

Very generous of you Dipper  

 

 

Have got a garage full of parts from my old VX220 that are just in the way, will all be going in the scrap bin soon I think  

MAFs, cams, various sensors and engine parts, floormats, undertrays, coilpacks, loads of crap lol