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Hey guys, I need some help ASAP to pass aircare (live in canada, BC)

Car:
93.5 tt, single turbo, 3400 stall, map ecu, stock injectors, fmic...reinstalled factory cats.

Max allowable:

HC = 0.5000
CO = 9.3200
NOx = 1.2400

Test 1 - 94 chevron octane, single turbo setup remained same

HC = 1.1915 (failed)
CO = 7.4809 (pass)
NOx = 0.3269 (pass)

Test 2 - 94 chevron octane, some methohydrate, single turbo setup same

HC = 1.3934 (failed)
CO = 6.5163 (pass)
NOx = 0.4058 (pass)

Test 3 - 94 chevron octane with MoHawk 94, removed map ecu, installed stock MAF, IAT sensor was still intact as its connected to the wired from maf, so i left it

HC = 0.5070 (failed by .0070)
CO = 1.2838 (pass)
NOx = 3.1272 (failed)


As you can tell the first 2 tests HC didnt come close to passing, but in the third test it almost did. On the chart, HC was only high during the 100 k/m run on the third run.

But NOx failed horribly after te stock maf was installed. I did notice when i woudl go into any boost my wideband would read 17+, so it was leaning out for some reason.

Any suggestions, i need to pass by saturday.
 

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It appears that excessive HC is your biggest problem. Reinstall the MAPECU and retune so that with the primary O2 sensor unplugged so that it is at 15 - 15.5 AFR range throughout the closed loop vacuum and RPM zones (680 - 3800 RPM). This should minimize HC. Install a new O2 sensor and reconnect. The closed loop system will make some corrections but it should be on the lean side of stoich. Make sure that your EGR valve is not plugged off (block off plates) or disabled. This should help with dilution and control of NOx as you lean out. Make sure that you run it hard to heat up the cats prior to bringing for the test. Make sure you tune for the fuel you will be testing with. Husky or Mohawk with 10% ethanol content should help.
 

· Registered
Joined
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748 Posts
It appears that excessive HC is your biggest problem. Reinstall the MAPECU and retune so that with the primary O2 sensor unplugged so that it is at 15 - 15.5 AFR range throughout the closed loop vacuum and RPM zones (680 - 3800 RPM). This should minimize HC. Install a new O2 sensor and reconnect. The closed loop system will make some corrections but it should be on the lean side of stoich. Make sure that your EGR valve is not plugged off (block off plates) or disabled. This should help with dilution and control of NOx as you lean out. Make sure that you run it hard to heat up the cats prior to bringing for the test. Make sure you tune for the fuel you will be testing with. Husky or Mohawk with 10% ethanol content should help.
Oh and BTW do all of the above with new stock plugs installed and set to stock gap. Colder plugs at smaller than stock gap will typically increase HC count due to misfires at idle/light loads.
 
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