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hey guys i have been stuck with a 2010 Chevolet Impala 3.5 . we bought the car from auction needed a transmission. we replaced the transmission. and then sold the car but in NYS we have to pass inspection in order to retail it. we have drove the car 300 miles and have not been able to set the evap or o2 sensor monitor. we can pass inspection if either one of those 2 monitors get ready. no pending codes , i'm kind of lost on this one. i monitored fuel trim and noticed stft would jump to around -18 intermittly on what seems to be decel. its hard to make it reproduce it tho.
any suggestions would help.
ive done 1000's of drive cycles this one is kicking my butt.
oxygen sensors flucuate bettween 200mv -800mv . i didn't mention. sensor 2 seemed to be responding slow to me, so we also replaced it with a ac delco sensor. i will get your fuel tank pressure number tommrow. i know evap monitor is extremely hard to set, and we almost never get it to set. i am more focused on the o2 montior.
Please clear all fault codes and perform a drive cycle as follows:
make sure these conditions are correct before starting
1. voltage between 10 and 15 volts
2. barometric pressure is greater than 75 kPa ( 10 psi )
3. the engine coolant temp is greater than 23 degrees F
4. Intake air temp. is less than 104 degrees F
5. the difference between the IAT, and ECT are within 37 degrees F
6. The engine has been off for more than 6 hours
7. Fuel level is between 25, and 75 %.
fuel level is a huge one, other wise the EVAP monitor may not run.
start engine and idle for 2 1/2 minutes
accelerate, apply 1/2 throttle to 55 mph, hold steady for 3 minutes
decelerate, do not shift, touch the brake or clutch, its important to let the vehicle coast down gradually to 20 mph
accelerate at 3/4 throttle to 55-60 mph, drive steady for 5 minutes
decelerate down to 20 mph.
return to work shop and turn off engine, then let vehicle sit for at least 5 hours,
complete drive cycle again, then park, and turn off car, Evap test should launch after key off
let vehicle sit for 1 hour, then recheck monitors and see if they have all completed.
EDIT.......If this does not work, I would use a scan tool and you can perform the " Evap. Service Bay test " which will guide you through idling, driving, and soaking via the scan tool to force run the evap monitor.
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