[Wrxdad18]

I am having an issue with my 2018 Subaru Wrx. When I turn the key to the ignition on position the fuel pump primes for 2-3 seconds and then stops, then it comes back on and primes again for 2-3 seconds. This continues until I turn the key all the way to turn the vehicle over. The car runs and seems to have no issues, but it’s throwing a flashing check engine light. Since this has happened I have replaced the fuel pump completely along with replacing spark plugs. Could it be fuel pressure regulator or fuel pressure sensor?

 

[XJman]

What's the code?

 

[Wrxdad18]

The car is tuned. Their are no codes that show.

 

[zax]

Why do you assume it's a fuel system problem?

A misfire can equally be caused by spark plugs and coilpacks as well as MAF sensor mis-scaling.

My post in your previous thread is just as applicable now as it was 3 months ago.

Misfires can be as much from the ECU calibration as from a mechanical issue.

You said "my car has been modified for a while," sure, but are you aware that the tuner has modified compensations on the ECU that depend on ambient conditions? What is "fine" in spring or in summer may present an issue in the winter. I'm not saying you shouldn't ferret out potential mechanical issues, but you should also be aware the ECU calibration may play a much bigger part in this story despite what your tuner may tell you.

 

[Wrxdad18]

Because I’ve replaced the spark plugs and the MAF sensor is new. Coil packs are good… Subaru dealership said there is no misfire