GM OBD-II drive cycle help

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Eric Wong
Posts: 69
Joined: Thu Jul 20, 2017 11:57 pm
Car#: 900

GM OBD-II drive cycle help

Post by Eric Wong » Wed Apr 03, 2019 2:51 pm

I replaced a clogged AIR valve on the old gasmobile, cleared the code, and now I need to complete the OBD-II drive cycle for smog testing...

Unfortunately, the drive cycle procedure is difficult to follow and seems like an accident waiting to happen:
http://www.obdii.com/DRIVECYCLE.HTML

Evap and EGR readiness still haven't come on after several attempts and near-accidents (I only need one of them to be ready for a '99).

No new error codes since the AIR valve replacement...

12V battery seems good (no unintended trip resets), so it's not losing information between drives.

Is there a safer, more reliable way of getting either the Evap or EGR ready?

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Anthony P.
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Car#: 30

Re: GM OBD-II drive cycle help

Post by Anthony P. » Wed Apr 03, 2019 8:00 pm

Drive 50 miles or so. Usually after enough miles it forces it.

Eric Wong
Posts: 69
Joined: Thu Jul 20, 2017 11:57 pm
Car#: 900

Re: GM OBD-II drive cycle help

Post by Eric Wong » Thu Apr 04, 2019 1:07 am

Just put in another 50 miles (highway, offramps, onramps) and that didn't work, either. Started at just over 1/2 tank.

I've put in over 180 at this point, actually; but I might've missed the 1/4-3/4 tank range on some tries since the fuel tank is V-shaped and the gauge gets thrown off by hills.

It occurs to me that I rarely hit 1/2 throttle on public roads (LS1 power); so I'm probably under-throttling the part which requires 3/4 throttle, or I'm overshooting the 20-55mph acceleration.

Maintaining 55mph is also tricky with elevation changes and no cruise control.

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Anthony P.
Current CSCC Overall Champion
Posts: 1065
Joined: Thu May 15, 2008 11:30 am
Club: SCNAX
Car#: 30

Re: GM OBD-II drive cycle help

Post by Anthony P. » Thu Apr 04, 2019 9:59 am

Hmmm, yeah fuel between 1/4 - 3/4 and more cold starts I guess.

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