Lean at 5psi..
 

Alright guys and gals, I'm in need of some assistance.

I recently bought a 93 rx7 for a screaming deal and so far its been nothing but a headache.

The issue im having right now is as soon as it hits 5psi it goes lean. 11.5 until 5psi no matter whay rpm then suddenly 14-16afrs. I've tried adding fuel and no dice, so I'm very confused.

Mods consist of:
Bridgeport
Gr3586r
Full 3" apexi exhaust
Synapse wastegate
Big fmic
850/1680 injectors 30% transition 1.5ms
Walbro 255 pump
Jegs afpr
Stock map sensor
Rywire engine harness

I should have MORE than enough fuel. So I'm not quite sure what the issue is. I ohm checked through the harness to make sure there were no broken wires and got resistance from all the injectors.

Any advice would be greatly appreciated.

do a fuel pressure test, while it goes lean. probably out of pump

I'm no tuner, but iirc "too rich" can result in "lean" readings....

When i i first got the car, the primary and secondary injectors were wired backwards because the previous owner ordered the harness backwards somehow.

So it was running 1680 primarys and it ran and drove just was rich at cruise. It got into boost just fine and held 15psi to 8k at 10.5 afrs after messing with the tune for a while. I dont think the pump not supplying enough fuel. But I'll have to figure a way to run a pressure gauge into the car.

I'm starting to think the pfc isnt actually firing the secondaries.

I've tried both ways, because ive heard that before. Something about it missing can cause a false lean reading.

the oxygen sensor only sense oxygen, so a misfire will show a lean spike.

that being said going from 10:1 to 16:1 you should feel that

Yeah it felt like a miss, and scared the crap out of me.

My secondaries are not kicking on. Do these have 2 injector drivers on the pfc or just one?

Am I getting too old, or did you forget to mention which ECU you are running???


Too rich misfire leaves all the oxygen unused. The O2 sensor measure that O2.
Fendamonky is correct but did you understand?

Its an apexi power fc. But come to find out the secondaries weren't firing due to a bad injector driver. I currently have it sent out to be repaired by a guy in Australia.

You'd be better off saving that money and just investing in a more capable ECU. Not necessarily bagging on the PFC, they have their place (sequential twins and/or sub-400whp), but there are SOOO much more capable ECUs available now.

Would you break out a Super Nintendo and use it for any reason OTHER than nostalgia? That is literally the difference in capabilities and production period technology, SNES vs PS4/XBOX1.

It seems more logical for me to spend 200 bucks to repair an ecu than spend 1-2k for a new one to start from square one. At least for right now.

Down the road I'll get a different standalone for sure, thats just not feasible right now. At least not while I'm paying on the loan.

One year and its paid off, then I'll go for a different ecu. The pfc is perfectly fine for what i need right now.

:dunno: your car, your call. Just would suck to have some other problem (in what seems like a problem car to begin with) pop up that causes you to lose a motor.

If its not fixed after i get the ecu back, or the ecu cant be fixed, obviously I'll get something else.

Do you have any recommendations?

AEM seems to have REALLY stepped their game up, and are reasonably priced for what you get. A lot of people seem to like Adaptronic as the new entry level ECU. Personally I'm having a LifeRacing (F88) installed over the winter, but that's higher on the spectrum.

Who will be tuning the car? ANY new ecu (that the mapper is comfortable and familiar with) should be a solid upgrade.. Ultimately you should be having the "what ECU to run?" conversation with that person, as they are going to be the ones working with it.

If I were to put something other than the LR in my own car I'd go with either Motec or AEM. But that's just me.

oh update. secondary injector driver took a shit. got it fixed by a guy in austrailla and works like a charm. just need to find a better damn base map to work off of.