Fuel Pressure Regulator on ej22 reconnected now idles strange

[BobBrumby]

Found A broken vacuum hose on gen2 liberty's ej22 it runs to the fuel pressure regulator so I reconnect it. Now when you first start the car the idle osilates between 250rmp and 1000rpm till it petters out after going up and down up to 2 or 3 times. I thought my car would run better with a functioning fuel pressure regulation system? Could this be the ecu relearning?

[OB99W]

The swings between 250 and 1000 RPM are called "loping", and with engines that have electronic management, that's usually a sign of A/F mixture that's way off. It's possible that the ECU had adjusted parameters (long term fuel trim, for example) to the previous condition, and indeed it's readapting. It's also possible that the pressure regulator isn't functioning correctly, etc. You could try clearing the ECU's memory (disconnect the battery for about 30 minutes), and see if the problem resolves; it might, or could return.

[BobBrumby]

Yeh that makes sence as it was adding petrol for the vacuum leak and now that its gone does not know what to do with the 'extra' air its now seeing. How do you test a fuel pressure regulator?

[BobBrumby]

Alright I just disconnected my battery, Ill see in the morning if anything happens. Do I need to hold the pedal for the floor for two seconds and then at half throttle for two seconds when I turn on the car before starting?

[BobBrumby]

Just an update: resetting the ecu has fixed the idle issue thanks for the help OB99W.

[OB99W]

Thanks for the feedback. I'm glad that resetting the ECU has apparently resolved the problem.