Help! Keeps failing emissions test.

[EduardoP0520]

Hello everyone.
I have a 2009 subaru Impreza 2.0r N/A (the mexican version of the 2.5) that keeps failing the emissions test due to high HC at idle. The limit is 100 ppm, my car got 109 ppm.

Idle measured (limit): HC 109 ppm (100 ppm), CO 0.23% (1.0%), CO+CO2 14.7% (16.5%), O2 00.6% (2.0%), lambda 01.02, RPM 814
2500 RPMs measured (limit): HC 40 ppm (100 ppm), CO 0.12% (1.0%), CO+CO2 15.2% (16.5%) O2 00.1% (2.0%), lambda 1.0, RPM 2549.

I already changed the oil, air filter, spark plugs (ngk iridium), cleaned the MAF sensor, took the fuel injectors to get cleaned and analysed, ran some catalytic convertor cleaner (Liqui Moly), put some premium unleaded fuel (91 octane in Mexico) and drove it hard for about 20 minutes before the test (half to full throttle until 6500 rpms). It failed before due to the same reason, high HC at idle (never over 200 PPM). What would you suggest? What could be causing this emissions failure?

I'd appreciate the help.

 

[bmart]

I'll google for you...

What Causes High Hydrocarbon (HC)? | SmogTips.com

Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible...

www.smogtips.com

What could cause high HC and CO, but low NO and CO2 in a smog test

Despite my confidence in having a (relatively) new catalytic converter and a new O2 sensor, my lovely 1994 BMW 325i Convertible got flagged as a "Gross Polluter." The test results are summarized be...

mechanics.stackexchange.com

 

[EduardoP0520]

I'll google for you...

What Causes High Hydrocarbon (HC)? | SmogTips.com

Below are common failures which are likely to produce high Hydrocarbon HC. Hydrocarbons are basically raw fuel, otherwise known as Gasoline. High Hydrocarbon (HC) emissions are almost always a sign of poor fuel ignition. However, it's not always that the engine's ignition system is responsible...

www.smogtips.com

What could cause high HC and CO, but low NO and CO2 in a smog test

Despite my confidence in having a (relatively) new catalytic converter and a new O2 sensor, my lovely 1994 BMW 325i Convertible got flagged as a "Gross Polluter." The test results are summarized be...

mechanics.stackexchange.com

Thank you for the googling, I've done quite a bit myself. The second post you reference is actually with high HC and CO, while my car only has high HC and low CO, which is quite the opposite.

Thanks, still.

 

[Grumpy1950]

First post above references possible intake leaks or vacuum leaks. Perhaps a smoke test could help find something. Basically what this involves is hooking up a smoke generator machine and looking for leaking smoke from hoses, intake system joints etc.

 

[Dick Foster]

Could be your CAT is trash.
It doesn't take much to consign a CAT to the trash heap. Oil consumption, manifold leaks, fuel regulators, bad O2 sensors, etc.