Hesitation/Bogging under slight throttle

[project_EM1]

Like title states I am having an issue with my gsr swap in my em1.

It is hesitating/ bogging under part/ light throttle situation.(i.e. coasting/cruising )

Wideband reading jumps from low 13 to high 16 during the hesitation/ bogging.

Compression: 220 across all cylinder
Distributor: checked with a known good one
Spark plug wires condition: good
Spark plugs condition: all fine but cylinder 4 had a slight carbon build up compared to the others 3
Timing: is correct
Cel codes: none
Coolant system: no leaks and no air
Grounds: all connected and secured
Clutch and flywheel: recently installed both new clutch kit and flywheel around february
Fuel filter: replaced mid last year
Primary o2: replaced last year with a denso o2
Secondary o2: replaced last week with a denso o2
Fuel pump: walbaro 255 pump
Fuel regulator : aem set to 42 psi on idle

I'm running out of ideas of what it could be. So if anyone has a suggestion to what I could check next or what the problem can be. Please do chime in and give me a hand.

[green91]

Check ignition timing with a timing light, make sure you're using the correct mark on the pulley.

High 16s while in any amount of throttle is very lean, are you setting the FPR with the vac hose off to set the idle pressure? An adjustable FPR really isnt necessary in most cases.

Im assuming you've got stock ECU?

[project_EM1]

Check ignition timing with a timing light, make sure you're using the correct mark on the pulley.

High 16s while in any amount of throttle is very lean, are you setting the FPR with the vac hose off to set the idle pressure? An adjustable FPR really isnt necessary in most cases.

Im assuming you've got stock ECU?

I'll check with a timing light when possible.
Fuel pressure was set with the vac line off at idle. I needed the regulator because of the walbaro pump it was pushing my fuel pressure into the high 50s on idle. And yea stock p2t ecu.

[green91]

Yeah ignition timing is the most likely cause, check that first for sure.

[project_EM1]

Yeah ignition timing is the most likely cause, check that first for sure.

Ok but it doesn't happen all the time. It's random can it still be a timing issue.

[green91]

Depends, the ECU changes the timing depending on the load (map value), RPM, & knock (if yours has knock). So yeah i'd definitely check with a light. Make sure you jumper the connector too.