Emission Fail at Idle HC ppm and CO%

[New92]

Hey guys. Need some advice here. After getting my emissions test I failed at Idle for the following:
HC ppm Allowed: 220 Reading: 235
CO% Allowed: 1.20 Reading: 1.70

I replaced the coolant temp sensor (which was quite old). Idle was achieved much faster and smoothed out, RPM's stabilized and the rich fuel smell seemed to be less pronounced. It was still backfiring after hard pulls under boost at high RPM and whenever I gassed it then immediately got off and back on the accelerator.

Retest results:
HC ppm Allowed: 220 Reading: 267
CO% Allowed: 1.2 Reading: 2.38

At 2655 RPM readings are as follows:
HC ppm Allowed: 220 Reading: 047
CO% Allowed: 1.20 Reading: 0.85

I have been running a MAF code 32 since I got the car. Ive swapped MAF's and cleaned both units. I still get the code. Since adding my 3" turbo back, uncatted, I throw a code 23 and 49 when in closed loop on the highway. Ive cleared the codes twice and they still come back when I get on the highway. The code 32 never leaves.

I know the obvious is to add a cat and muffler which I plan to do. Problem with that is Im still on a budget. I had just replaced a leaking radiator and a swiss cheese exhaust so Im feeling the pinch. I know that plenty of guys here run uncatted on the DP and have no issues so Im thinking the answer lies elsewhere. My fuel economy seems to be a bit better, after replacing the temp sensor, but Ive not had the chance to run it through a full tank to confirm. It seems like its still mixing super rich (smell and backfiring) and Im not too sure where to go from there. Should I look at getting a JECS MAF? Will this help the run rich issue or make it worse? I currently have the Hitachi aluminum one (well two of them). Would a cheap high flow cat be enough to correct the readings? Im hesitant to go down that path as it seems like that would just be masking the underlying issues.

List of related mods:
-Desnorkus
-Coffee Cup intake mod
-K&N pannel (replaced with factory for now)
-MBC set at 10lbs
-TMIC
-Type S bov recirculated

Recently replaced:
-Coolant temp (two pin)
-Radiator
-Thermostat (OE Subaru)
-Magnecore plug wires
-Oil change and filter
-Walbro 255 lph fuel pump

As always, thanks for the expertise and input.

Ben

[PhyrraM]

O2 sensor may be failing, keeping it too rich.

Throttle postition sensor can have dead spots leaving the ECU confused as to what to do. The idle switch could also be bad, leavin the ECU to think it never returns to idle.

Sensor grounds, brittle wires and open circuits can be a problem on our cars.

[wtdash]

HI,
32 is the O2 sensor, which likely needs replaced, since I don't see it mentioned. (Edit: PhyrraM beat me to it.)
23 is the MAF.

23- Air flow sensor - Abnormal voltage input entered from air flow sensor - Controls the amount of fuel (injected) in relation to engine speed and throttle sensor position

32 - Oxygen sensor - Oxygen sensor inoperative - none

Don't use the JECS - it'll run lean and cause other issues - like blowing up your engine.

Td

[Legacy777]

I posted instructions on how to check the MAF sensor in your other thread. You need to work on getting the codes to go away. No need to replace anything else at this moment. If you get the codes to go away, the car should run properly.

The O2 sensor may cause a slight issue, but based on your comment about backfires after hard pulls, I'd lean towards the MAF sensor since the O2 sensor won't be adding/doing anything in open loop.

If you don't already have it, d/l the engine & electrical manual from me, which has troubleshooting and wiring diagram info for all the sensors, which will help you narrow down the problem.

http://www.main.experiencetherave.com/s ... lectrical)

[New92]

Thank you everyone. Thanks Josh. I just responded in the other post. Ill update you guys on what I find out after learning how to use my meter, LOL.