I just failed the "readiness" check for smog. The tailpipe is fine. Guy asked if the battery had recently been disconnected. I said a year ago and about 2500 miles since. He said I needed to drive 45 mph for 15 minutes, stop for a few min then drive 55 mph for 15 min.
I don't own a test track so finding enough road where you don't have to touch your brakes or maintain those speeds is next to impossible
the "official" GM test states:
General Motors (specific) OBD II Drive Cycle [moderator Sherlock9c1 added photo of GM '96 Factory Service Manual (FSM), book 2, page 6E-466 on 10/13/2024]
Performing a GM OBDII Driving cycle:
Again...I don't own a private test track so being able to cold start and let idle with AC & rear defroster on for 2 1/2 minutes then accelerate to 55 mph for 3 minutes then decelerate NO BRAKES to 20 mph
Needless to say WTF...
So even though the car has passed smog every time, at the same shop for 15 years, and it has been about 3k miles since the last test with the only difference being a year ago battery was disconnected to replace. The battery has been disconnected dozens of times over the years for various reasons and passed the computer test by smog.
tail pipe passes with FLYING colors
Don't know if the guy is beating me up for retest $ but if this driving cycle has to be achieved...I will either get tickets, run over someone or certainly blow through some stop signs & lights doing so
suggestions?
I don't own a test track so finding enough road where you don't have to touch your brakes or maintain those speeds is next to impossible
the "official" GM test states:
General Motors (specific) OBD II Drive Cycle [moderator Sherlock9c1 added photo of GM '96 Factory Service Manual (FSM), book 2, page 6E-466 on 10/13/2024]
Performing a GM OBDII Driving cycle:
- 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.
- 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.
- 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.
- 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.
- Decelerate. Let off the accelerator pedal. AND!!!!!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.
- Accelerate. Accelerate at 3/4 throttle until 55-60mph (88-96 km/hr). This will perform the same diagnostics as in step 3.
- 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.
- Decelerate. This will perform the same diagnostics as in step 5. Again, don't press the clutch or brakes or shift gears.
Again...I don't own a private test track so being able to cold start and let idle with AC & rear defroster on for 2 1/2 minutes then accelerate to 55 mph for 3 minutes then decelerate NO BRAKES to 20 mph
Needless to say WTF...
So even though the car has passed smog every time, at the same shop for 15 years, and it has been about 3k miles since the last test with the only difference being a year ago battery was disconnected to replace. The battery has been disconnected dozens of times over the years for various reasons and passed the computer test by smog.
tail pipe passes with FLYING colors
Don't know if the guy is beating me up for retest $ but if this driving cycle has to be achieved...I will either get tickets, run over someone or certainly blow through some stop signs & lights doing so
suggestions?