The Subaru Dealer just reflashed my Subaru per WVU-31 and now it stalls, what’s going on?
A. On 2005 and newer models care must be taken when reflashing the engine control module or disconnecting the battery for any reason. The most critical part of this is turning the key to the on position prior to starting the vehicle and waiting for the systems to “settle a bit” before starting. With the WVU-31 its obvious that the guys at the Dealer were in a hurry and in many cases delivering back vehicles with problems to customers.
If you have a situation where the car dies at idle, or idles erratically after the battery has gone dead, has been replaced or new engine management software was installed understand the base idle “map” must be rebuilt and until this is done it will continue to struggle to idle properly. I advise turning the key to the on position for 30 seconds, back off, than back to the on position for 30 seconds than finally start the vehicle.
If this happens to you the only thing that will help, is to drive it until it corrects it self.
Here is some information about the WVU-31 Campaign
https://allwheeldriveauto.com/subaru-service-program-wvu-31/
Clean all the carbon from the throttle body….over time the throttle body slowly builds up carbon deposits and the ECM and TPS are able to compensate and establish a good idle point. If the battery goes dead or ECM is reprogrammed it will not idle because the ECM has to relearn its idle point.
The drive by wire vehicles are not to be cleaned. You must use caution if attempting and you must use the proper technique and chemicals.
-Justin
The first time after a flash the ECM needs to reinitialize, that’s why you can’t start it for 30 seconds or so after the key is turned on.
The stalling has to do with the learning parameters of the ECM. The ECM has learning tables for airflow and timing that it “learns” as you drive and it adjusts to your environment. With a little driving it will settle out.
This is the reason why whenever I did a reflash when I was working at the dealer I’d turn the key on, wait a minute or so, start the car, let it idle for a minute or so, and then test drive it and verify it didn’t have and idle or drivability problems…