Walbro 255 install= surging & CEL (manifold pressure)

[Garrison]

Hi,

I'm prepping my engine for supercharging, and I've added a Walbro 255 fuel pump in place of the OEM unit. Now, if I hold the pedal steady in 1st or 2nd, the engine surges somewhat; Also, I've been continually getting the code for incorrect manifold pressure (barometric range problem), despite ECU reset and code clearing. Now, I have 2 questions:

1) Why is this happening? I though that the fuel pump was only supposed to provide as much fuel as the engine asks for.
2) Will this problem (and CEL) persist once I've added boost to the equation, or will the added air balance out the added fuel?

Thank you kindly for any responses.

[chuckthefuk]

Did u change the fuel filter by anychance?

What exactly is the CEL code?
viewtopic.php?f=59&t=13696&hilit=+obdii (https://sl-i.net/FORUM/viewtopic.php?f=59&t=13696&hilit=+obdii)

[Reason]

I did a 255 walbro with no issues last week. In fact my car seems smoother now.

[Garrison]

Chuck, I did replace the fuel filter recently. Have I got the lines backwards? (I was unaware that that mattered).
And as for code, I'm not sure. I'll go double check, but I think my code reader just gives the name of the code and not the number. If so, I believe the CEL# to be: P0106 *Pressure Sensor Circuit Range Problem

[Reason]

Yes it matters...

[Garrison]

Yeah, I didn't even think to make sure I was doing right, despite the fact that I knew there was a proper and improper way to do it (I misspoke in my above post). Whoops. It's fixed, but the code is still showing up. ECU reset?

[Huffer]

ECU reset. :)

[Garrison]

Cool, thanks. I'll update you guys after I get a chance to play with it again.
Since this is my thread anyway, is running around with a prepped-for-boost engine (fuel pump, 4:1 Vortech, 1-step colder NGK plugs) while I figure out the plumbing a poor decision? I've done a decent amount of reading for this project (Thanks to Skidd, anothernord, and everyone else who did a write-up, they helped tremendously) but I just want to make sure I'm not missing anything.

[chuckthefuk]

IF you use a piggy back or stand alone then there is no reason why ignition, fuel and air should be giving you issues when you dial in the right settings.

[Garrison]

Post ECU reset: The surging problem has greatly diminished, and is no longer troublesome.
The code however, remains.

[chuckthefuk]

WHAT CODE IS IT!!!!!!

P0***

dont' guess don't assume

[Garrison]

Oh my bad, I never confirmed that with you guys. It turns out that is is P0106, my code reader says it at the top left and I just missed that detail before.

[chuckthefuk]

https://sl-i.net/FORUM/viewtopic.php?f=1 ... &view=next (https://sl-i.net/FORUM/viewtopic.php?f=11&t=13933&view=next)

[Garrison]

So you're saying that my vacuum lines are mixed up somewhere?

[rougeben83]

If you replaced the fuel filter, you may have yanked a vac line loose, check around the area to make sure.

[Garrison]

Got it, it was the T-shaped vent line that's after the filter, coming from the Pressure Sources Switching Solenoid Valve.
All codes cleared, and happy days for the soob.
Thank you everyone.

[chuckthefuk]

Noice!