Navy01Coupe

So, I failed my emissions part of my inspection and am going through the process of cleaning things up to pass it. First step was I changed my air filter and cleaned my MAF this weekend. I plan to do the Drive Cycle next (posted at bottom of post).

My questions are:

1 - Does it need to be done in this order and can other things happen in between?
2 - Also, my AC compressor is dead (that’s next on the to do list). Will I be able to put enough of an electrical load for #2 without it?

I am not close enough to a safe place to do steps 3-8 unless I drive about 2-3 miles from my place.


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General Motors (specific) OBD II Drive Cycle

Performing a GM OBDII Driving cycle:
1.Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 122°F (50°C) and within 11°F (6°C) of the ambient air temperature at startup.
Do not leave the key in prior to the cold start or the heated oxygen sensor diagnostic may not run.

2.Idle. The engine must be run for two and a half minutes with the air conditioner on and rear defroster on. The more electrical load you can apply the better. This will test the O2 heater, Passive Air, Purge "No Flow", Misfire, and - if closed loop is achieved- Fuel Trim.

3.Accelerate. Turn off the air conditioner and all the other loads and apply half throttle until 55mph (88km/hr) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

4.Hold Steady Speed. Hold a steady speed of 55mph (88km/hr) for 3 minutes. During this time the O2 response, air Intrusive, EGR, Purge, Misfire, and Fuel Trim diagnostics will be performed.

5.Decelerate. Let off the accelerator pedal. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 20 mph (32km/hr). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

6.Accelerate. Accelerate at 3/4 throttle until 55-60mph (88-96 km/hr). This will perform the same diagnostics as in step 3.

7.Hold Steady Speed. Hold a steady speed of 55mph (88km/hr) for five minutes. During this time, in addition to the diagnostics performed in step 4, the catalyst monitor diagnostics will be performed. If the catalyst is marginal or the battery has been disconnected, it may take 5 complete driving cycles to determine the state of the catalyst.

8.Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.

3boystoys

What part of the test failed? Did you clear any codes just before the test or disconnect the battery recently?

Tech

In my state, you're able to have one of these tests marked as "incomplete" for a 2001 model year vehicle.

The drive cycle does not need to be in order and the AC is not required for #2.

Bill Curlee

What specifically failed the emissions test??.

Did you have an emissions not ready or did you fail something like CO2 / Hydro Carbons/ or a specific hard ware issue like O2 Sensor DTC??

You can go to Autozone and they can connect the ACTRON Scanner to you OBD2 Port and tell you if the PCM is Emissions Ready or NOT. That way when you go back, you will be good to go.

Clearing any PCM ( P Series) DTC or having a WEAK or Sub Par battery can and will cause emissions not ready. Every time you crank the car with a weak battery, you reset the emissions READY flag/s to NOT READY

Bill

Navy01Coupe

I came back with 2 'Not Ready" (am only allowed 1). I disconnected the battery to clean the MAF, and read that the fastest way to get them to "Ready" was to go through the driving cycle. Just wasn't sure if order was important.

LoneStarFRC

Was/is your "Check Engine" light coming on?

Navy01Coupe

It did last week AFTER I went to get inspected. I read/cleared the codes. It was showing a PO171 and PO174. When I researched them I got a 'to do list' of possible reasons. I have been going thru them one by one in hopes the codes do not reappear and that I am good to go on the emissions portion when I go back.

Navy01Coupe

Failed tests were:

Catalyst - Not Ready
Evap Sys - Not Ready

RedZMonte

P0171 and P1074 are both Lean codes. my guess is you have a Vac leak somewhere in the system causing it to read lean and fatten the system up.

Any mods to the car? Aftermaket Intake? MAF screen removed? Headers?

S

Navy01Coupe

I knew they were lean codes and have been going down a check list to correct. There are zero mods to the car. It is 100% stock with 167,000 miles on it. Vac Leak is next to check. I will need to Google/research how to do that. Vac leak also would explain the idle dropping to +/-500 from time to time.

Thank you ALL for your comments/assistance. LOVE this forum!!

lionelhutz

Take a good look at the PCV valve hoses. Comes off the passenger side by the throttle body and goes to the valve covers. The PCV valve is inline in the hoses.

3boystoys

You will NEVER pass till you fix the issue, when you clear the codes, you reset the I/M monitors which is what you failed. They will never go ready till you fix the issue and the CEL will come back on soon.

Navy01Coupe

After cleaning the MAF and running through the Drive Cycle a few times, I took the car to get re-inspected (today was last chance before I’d have to repay anyway). IT PASSED ! ! ! Only one “Not Ready” – Catalyst.

The idle is still dropping to 500ish sometimes, so I still have a problem to work on, but it isn’t an “emergency so I can drive legally problem”. It is now a “make the car work properly problem”.

Next, inspect the potential vacuum issue.