Need help with my RB25, running rich (in S30)

[AZhitman]

RB25 swap into a 1972 S30...

Recently serviced injectors. Walbro fuel pump. FPR functioning normally. The only thing different from stock is there's no ECCS relay on this install.

Symptoms: Running real rich, massive backfire on deceleration. When it's been running for a while, and I go to re-start, I can tell it's loaded up on fuel and won't readily start (if I open the throttle plate all the way, it'll clear the fuel and start normally).

Initially thought it might be a fuel pressure issue, but it's at 32 psi (idle) with vacuum, and 40-41 psi with vacuum disconnected.

I'm able to view all engine parameters via laptop, and nothing seems out of range.

I'm thinking I need a more robust monitoring program (like Consult) so I can look at each cylinder individually...

Any thoughts?

[Darius]

Check your injector o-rings. They could be leaking into the intake manifold if they are damaged. Lube those babies up with vaseline upon reinstallation!

[OutToWinPAHC]

Yea greg i would think injector issue, but have you pulled plugs? I wonder if its all cylinders or just singles. Also have you checked tps range and timing? The other thing you could have is a miscalulation of air so ecu is compensating for fuel

[Darius]

Definitely pull the plugs to see which one(s) are wet or if all of them are wet.

[Carl H]

sounds like damaged orings.

[LeD ippen]

unplug the coolant temp sensor and see what happens. i had this happen on my rb20 and a civic it was flooding while starting till i unplug it (change it after i saw the difference)
i also had problems where the ecu coolant temp sensor made the car run rough

[LeD ippen]

or a bad maf/map sensor

[AZhitman]

I'm pretty sure the o-rings are good... New ones with the injector service.

Could this be a bum coil pack?

[OutToWinPAHC]

could be, but you should hear the miss.... sounds like a subbie. If you need S2 coil packs I still have a few

[Darius]

I wouldn't rule out injectors just because they are new. I tore a couple new o-rings during installation once and it ran like crap.

Either way, you should be able to narrow it down by pulling the plugs and inspecting them.

[AZhitman]

I didn't R-square the injectors, I had the rail service done at Deatschwerks (see homepage article). Pulling injectors is a PITA.

Thanks Kev - It doesn't seem to idle as smooth as an RB typically does, so I'll check that next.

[OutToWinPAHC]

call me if you need anything I got spares

[Yellow4g63]

you could build a psi tester and then build 5psi in the system and then crack the throttle open and see if you have a leak around the injectors. soapy water sprayed around the injectors and it should bubble up if it's leaking.

[Carl H]

even if the injectors have been serviced it is easy to tear them when installing if not done right...pull the rail and see if its loading up on fuel.