My brother has a problem with his Fiesta, and seeing the last time I did anything performance related on a Ford it involved fiddling about with carburettor jets, I'm hoping someone here might be able to shed some light on this for me.

The car is a 2015 1.0 EcoBoost Zetec S (123), about 55k miles on the clock, with new engine fitted under warranty about 12k miles/18 months ago.

The stage 1 remap and induction kit was fitted September 2021.

MOT emissions test results Jan 2021 (BEFORE remap and induction kit fitted): pass
@2980rpm
CO: 0.07%
HC: 34 ppm
Lambda: 0.999

MOT emissions test results Jan 2022 (AFTER remap and induction kit fitted): fail
Test#1:
@2780rpm
CO: 2.51%
HC: 138 ppm
Lambda: 0.927
Test#2:
@2870rpm
CO: 2.86%
HC: 181 ppm
Lambda: 0.918

Following the most recent (failed) test, the test technician has concluded that the cat has failed and needs replacing.

I only have limited knowledge of these things, but the high CO/HC and low Lambda figures suggest to me that the engine is over-fuelling, so while I can understand why the cat might have become damaged as a result of this, I'm concerned that this just a symptom, rather than the root cause of the problem, so I'm trying to establish whether the remap and induction kit might be to blame.

Does anyone with experience of remapping know if garages normally do some form of exhaust emission testing during or after a stage 1 remap, or is it just a case of upload the new map, then a quick road test and job done ?

I'm wondering if the new map was an "off the shelf" product, meant to work with standard components, which doesn't take into account the increased flow of the induction kit (just guessing, tbh...) ?

The replacement cat might get the car through the MOT, but if the cause of the problem is still there, it might be wrecked again by the next MOT.

Any words of wisdom would be much appreciated.

Sounds like a bad map imo. Induction kits rarely make a difference other than looks/sound or increased intake temps - as long as they haven't messed with the MAF/MAP sensor (If forget which are on this engine).

I'm surprised it's been mapped after already having a new engine.

It also depends on who mapped it as to what they did. It doesn't just have some race chip attached does it?

Who is the remap from?

This is the reason I hate "stage" maps. They're completely meaningless as the supporting mods can have a massive impact on how the fueling, timing etc. needs to work.

@alexp999, @Luke4efc 

Thanks for the replies - as far as I know it was just a software change - no race chip attached.

I'm reluctant to name the garage at this point, but I believe they said they use EcoTune software, even though EcoTune seem to specialise in VAG tuning.

I think its a MAF sensor, and it is the original unit - just transferred over to the new mounting hole on the pipe behind the replacement air filter housing. Looks like the mounting hole is shaped so you can get only get the sensor in the right way around, which I guess is important if its measuring flow rather than pressure. 

I had a 1998 escort which had a similar mot fail. There was talk about it needing a new cat but after replacing the o2 sensor (between the engine and cat, not after the cat) it was fine and passed.  I found someone who knew what they were doing and they monitored the voltage from the sensor and looked at the length of time the injectors were opening. He said from looking at that he felt that the o2 sensor was faulty which seemed to be right. I wouldn’t know what the voltage and length of opening might be.  These days I think you can use forscan software to monitor these.   But having said that I would think that an out of spec voltage from sensor might cause eml to illuminate

Just to close out this topic for the benefit of anyone reading this some point in the future - the cat was replaced, emissions figures were then back to being well within pass limits. Car was returned to the place where the remap was originally installed to verify the map and confirm there was nothing wrong with it. The conclusion we have now reached is that the cat may have been damaged by a misfire which was a symptom of the engine failure which led to it eventually failing and being replaced under warranty a year earlier (see: https://www.honestjohn.co.uk/news/miscellaneous/2018-08/urgent-appeal-to-owners-of-ford-10-ecoboost-engines/). The extra fuelling as a result of the remap may just have been enough to finish the cat off. We don't have any proof of this - just a theory really.