Decat Causing Issue? Overfueling?

I have a decat 4-2-1 Janspeed on a coilpack Micra.

I have screwed an extender onto the second lambda and am still getting a check engine light with the fault code being 'cat efficiency'.

There is also a strong smell of fuel fumes surrounding the car when stationary in traffic etc - I am running Almera 1.5 (QG15) injectors by the way.

Can anyone advise or is this just another example of why a remap is important when modding a car?

I think the MAF is also now faulty as the idle is a bit shaky and it likes to stall at low RPM.
The cause I think is just general wear and tear I guess as this happened once on my old CG10 as well.
The faulty MAF is causing the car to release a weird gassy smell when the car is stationary in traffic - is this a normal symptom of a bad MAF?
 
Last edited:
Lol fair enough. But I thought given that the car is is modded now (100-105bhp), it would need bigger injectors?
Without tuning it still thinks it's got standard injectors so it's still putting in the same injection pulse width, yes you might need more fuel up high but at idle isn't going to change.
The ECU is probably finding it hard to correct fuel trims enough if it is able to get worthwhile readings from the extended o2 sensor (it might not use that 2nd? o2 sensor for closed loop).
 
Without tuning it still thinks it's got standard injectors so it's still putting in the same injection pulse width, yes you might need more fuel up high but at idle isn't going to change.
The ECU is probably finding it hard to correct fuel trims enough if it is able to get worthwhile readings from the extended o2 sensor (it might not use that 2nd? o2 sensor for closed loop).

Okay sounds like I need to stop messing around and just get the remap done by Tornado tbh - this will sort the overfueling issue, it will sort out the engine light due to the decat and will allow me to gain full benefit of all the other mods, so it makes sense to do it then.

Will get the MAF sorted first though.

Appreciate the help.
 
EDIT - screwing the extender onto the second lambda has actually eliminated the engine light on cat efficiency code.

The engine light remained on for another reason (MAF).

So just to let people know as a confirmation, screwing an extender onto the second lambda on a decat coilpack Micra WILL eliminate any 'faulty lambda' engine codes.
 
Top