CA18DET "MOT" pollution

[Jyttah]

Hi.
I just gotten my S13 to the danish version of MOT. And it failed because of pollution.
Its a newly renovated engine with new sensors (water, exhaust and everything) and its bone stock besides a 320L AEM fuelpump. Even the catalytic converter is brand new.
Ive attached a readout from the MOT.
the CO is the issue here, Its not allowed to be over 0.5, and as shown on the picture its on around 1.728.

My thought is that the fuelpump gives to much fuel, so the car is running rich. In this case, would a fuel regulator change the outcome?

 

[r3k1355]

Are you pre or post facelift?

 

[Jyttah]

Its a 1992 model

 

[r3k1355]

You need to make sure you have the correct matching ECU and AFM for your model, mixing pre and post facelift bits can cause problems.

 

[Jyttah]

You need to make sure you have the correct matching ECU and AFM for your model, mixing pre and post facelift bits can cause problems.

I did not know that there's difference in the AFM. But both ECU and AFM is original for this car.

 

[Jyttah]

A quick update.
I can see the difference is if the car has a lambda sensor or not. The one without lambda have a AFM with 4 wires, and with lambda sensor, it only have 3. So that can not be the issue.

 

[r3k1355]

and you have the correct the ECU?

 

[Jyttah]

Yes. The ECU is the correct and original one.

 

[r3k1355]

You should run through the injection manual inspections, check each sensor is giving a reading within spec.

CA18DET injection manual

What fuel pressure regulator are you currently using?

 

[Jyttah]

You should run through the injection manual inspections, check each sensor is giving a reading within spec.

CA18DET injection manual

What fuel pressure regulator are you currently using?

Thanks. Ill look into that.

And the engine still have the OEM pressure regulator.

 

[r3k1355]

The OE pressure regulator is pretty reliable, although they are quite old now. You could always fit a fuel pressure gauge and see for yourself.

Have you have the injectors cleaned and tested, to check their flow rate is what you are expecting it to be?

 

[ard]

Stock euro S13 has a restrictor in the fuel return line somewhere near the fuel filter. I've worked on several cars that had high fuel pressure after fitting bigger fuel pumps and replacing a return fuel line helped.
my suggestion would be to check the MAF voltages and compare to what FSM suggests. Also do a boostleak, check the spark plugs, fuel pressure etc. if there is anything that helps then get a nistune board and tune it with WBO and it should pass the CO test.

 

[Jyttah]

Thanks to everybody for the suggestions.
I talked to a local mechanic, and he recommended to use sparkplugs gapped to 1mm, and also tested the catalytic converter, and the result was that it was dead. So a new cat and some sparkplugs, and it passed without any issues.