Help! I failed Emissions for the 2nd time, worse than before!


Oct 26, 2018
2018 !st attempt
HC GPM: 3.8172 Limit 2.5 Fail
CO GPM: 14.3584 Limit 20.0 Pass
CO2 GPM: 494.6008
NOx GPM: 2.4582 Limit 4.00 Pass

2nd attempt
HC GPM: 9.475 Limit 2.5 Fail
CO GPM: 39.5179 Limit 20.0 Fail
CO2 GPM: 494.6008
NOx GPM: 2.4582 Limit 4.00 Pass

Trying to give all the info I can. I have no idea what to try next. Seems like I am throwing money at this thing and making it worse.

This is what i have done between tests. New O2 Sensor (new sensor has slow CC counts, bad new O2 sensor?), Removed all oil from all the K&N Filters, Cleaned MAF with MAF cleaner, Cleaned throttle body, New Spark plug wires, New 180 degree Thermostat, dropped fuel pressure. 93 Octane Fuel

Already had new NGK UR4 plugs, Oil/filter change. Fuel pump was replaced about 4 months ago, buy the body shop (car died) OEM fuel pump installed and the car has a hotwire kit already installed. (will have to replace with a high flow.) running TT Emissions Chip, Turned down the RJC Boost controller.

Noticed a small leak between downpipe and Catalytic Converter (would this affect the test?) Same leak was there for both tests.
Have not swapped PCV Valve

SM-G Readings after returning from 15 mile trip.

737 mv O2
MAF: 3
LV8: 23
Voltage: 13.8
Int: 125-131
BLM: 155
Temp: 192.2
Air Temp: 120.2
TPS: .42
IAC: 39
O2 CC: counts slow 2-7


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Last edited:
What chip? If it's a performance chip, your car may not pass because of the way the chip's calibrated. You should consider swapping to the emissions chip that Turbo Tweak sells.
Currently running the TT emissions Chip.

So I put the Turbo Tweak chip back in and my numbers seem a little better. Do these look more on the normal side?

871 mv O2
MAF: 4
LV8: 31
Voltage: 14
Int: 128
BLM: 134
Temp: 170
Air Temp: 125
TPS: .42
IAC: 27
O2 CC: counts slow 5-10
Open Loop
I would think his emissions chip would have closed loop idle but you still have a rich idle number on the O2 volts. If you rev it up in neutral and hold to 2000 rpm do the O2 volts switch up and down constantly as they should? Prolonged idle can cause the sensor to get lazy. revving up adds some heat and helps it become active again.
Finally passed emissions. Replaced all vacuum lines, increased fuel pressure, increased IAC, reduced TPS, regular unleaded fuel and bang. I didn't hurt that the technician was drooling over the car.

3rd attempt
HC GPM: 08746 Limit 2.5 pass
CO GPM: 3.4454 Limit 20.0 pass
CO2 GPM: 488.5996
NOx GPM: 2.8255 Limit 4.00 Pass
Can we get the new scanmaster numbers that go with passing the test?
Something changed with your latest wrenching.
When ever I had to pass emissions and was failing i'd throw in a 195 deg. Tstat and new plugs which always worked.