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Username Post: Readiness "drive cycle"?        (Topic#181825)
GaryC 
Very Senior Member
Posts: 2673
GaryC
Loc: Pittsburgh, PA. U.S.A
Reg: 02-28-03
02-10-08 07:54 AM - Post#1362747    

Hi All,
Is anyone familiar with the correct "drive cycle"
required on a'99 Cavalier to put the OBD-II "monitors" in a "ready" state? We had the batttery disconected for a few days while woking on the car, took it in for PA state inspection yesterday, all safety items good, however could not complete emmissions test because of computer needing to relearn itself. The inspection mechanic said to drive it for a few days and bing it back. After reading up on it performimg the correct drive cycle ensures all "monitors" are ready for testing. I have found a generic drive cycle but I guess there are specific ones for every vehicle (or computetr).
Thanks.
1957 Chevrolet Bel Air coupe, 300hp 327, M20 4 speed


 
GaryC 
Very Senior Member
Posts: 2673
GaryC
Loc: Pittsburgh, PA. U.S.A
Reg: 02-28-03
02-12-08 07:19 AM - Post#1364286    
    In response to GaryC

I did run accross these 2 scenerios:

Re: OBD2 & Emissions testing

------------------------- ------------------------- ------------------------- -----

I found this "How to" to complete a drive cycle for GM.

A complete driving cycle should perform diagnostics on all systems. A complete driving cycle can be done in under fifteen minutes.

To perform an OBDII Driving cycle do the following:
Cold Start. In order to be classified as a cold start the engine coolant temperature must be below 50┬░C (122┬░F) and within 6┬░C (11┬░F) of the ambient air temperature at startup. Do not leave the key on 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 88km/hr (55mph) is reached. During this time the Misfire, Fuel Trim, and Purge Flow diagnostics will be performed.

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) 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. Do not shift, touch the brake or clutch. It is important to let the vehicle coast along gradually slowing down to 32km/hr (20 mph). During this time the EGR, Purge and Fuel Trim diagnostics will be performed.

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

Hold Steady Speed. Hold a steady speed of 88km/hr (55mph) 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.

------------------------- ----------------------

There is no drive trace as a whole, however, some monitor cycles are similar and may pass through simultaneously

Catalyst moniotor:

Pre-req: no codes present, IAT above 32 deg f; ECT is above 167 deg f; mass air flow greater than 15 gm/s, engine load is below 63% and steady, engine speed is below 3000 rpm

-Idle vehicle 5 minutes until it is in closed loop

-drive 5 min at steady speed above 50 mph

-drive 2 min at steady 40 mph

-drive 2 min at steady 50 mph

EGR Monitor:

Pre-req: no codes present, ECT is avove 75 deg f; barometric pressure above 72kPa

1. Idle vehicle 5 minutes until it is in closed loop

2. Accelerate and drive for 1 min at steady speed above 50 mph

3. coast vehicle down to 20 mph (vehicle in drive or w/ clutch engaged, brake off)

4. repeat steps 2 and 3 four times

* the GM egr runs during the deceleration portion of the drive trace

Evaporative Monitor:

Pre-req: no codes present

-drive 5 min at steady speed between 30 and 60 mph

-stop and idle 2 min

O2 Sensor Monitor:

Pre-req: no codes present, IAT above 32 deg f; ECT is avove 167 deg f

-Idle vehicle 5 minutes until it is in closed loop

-drive 3 min at steady speed above 50 mph

-drive 2 min at steady 40 mph

-drive 2 min at steady 50 mph




1957 Chevrolet Bel Air coupe, 300hp 327, M20 4 speed


 
GaryC 
Very Senior Member
Posts: 2673
GaryC
Loc: Pittsburgh, PA. U.S.A
Reg: 02-28-03
02-13-08 04:52 PM - Post#1365471    
    In response to GaryC

Update:

I pretty much followed the first drive cycle listed above. Put 140 miles on the car since the first "not ready for testing" from the inspection station. It passed today. The emmissions inspection mechanic said the Chevy's are the easiest to make the monitors "ready" for testing. I now know more about OBD-II than I ever wanted to :> I also bought a OBD-II scan tool for future problems with our cars.

Hope this helps someone else out, Gary
1957 Chevrolet Bel Air coupe, 300hp 327, M20 4 speed


 
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