hadleycat

1997 502 Mag with a M3sc Procharger running 7 lbs. boost.

At 5000 rpms and 7 lbs. of boost I have an AFR of 13.0. I think I am a little lean. What does everyone think?

I also believe i am maxed out on my 42lb. stock injectors?

At 5lbs. Boost I have an AFR of 11.5 which I believe is safe.

ezstriper

42lb not going to cut it...we run a 509, procharger, our own custom EFI and we run 90lb injectors...yes lean

4bus

iTrader: (4)

13 is way too lean on a boosted boat. I run 11.5- 11.9 at 8 lbs. I would not be comfortable with anything over 12 cause I like to get on it and not worry.

Who did the tune? Good chance you are out of injector like stated above. Boost referenced regulator? Fuel pressure gauge on the dash?

I know its not a whipple, but Dustin at whipple has but together some great tunes for guys using prochargers. If your ECM is stock, and you are using the pro charger "cheat" method I would suggest letting someone get in there and tune the BPW to boost table, at the very least

hadleycat

I took ECM to Tyler Crockett last week and he added more fuel in the upper RPM ranges. (Runs perfect until I get above 5 lbs. of boost). I have a feeling that I am out of injector now.

I am using Bell Cartech Boost referenced regulator with Autometer fuel pressure in dash. I also have the MEFI1 computer.

Running 80lbs. Fuel pressure at WOT

Not sure if I can upgrade my injectors on the 1997 502 Mag MPI Fuel rail but if I can find some that will be my next step. Till then Ill keep her at 5lbs. Boost and under

4bus

iTrader: (4)

Why not go back to Crockett and ask his opinion? The guy knows his stuff.

How much boost can those old MEFI units read? Any chance that anything about 5 psi is out of range of the MAP sensor?

80lbs is off the charts!

hadleycat

Yes I am definitely going to talk to Crockett. He has been a great help.

I dont believe the MEFI1 can read Boost at all.

4bus

iTrader: (4)

Well....that can be a problem It can read zero vacuum however, you can program a dump there but then you have problems. If you get it under 12 at WOT 7lbs it will be crazy rich at 1-4 lbs, no way to program a curve.

Have you asked him if he has a mefi3 laying around to program and switch out? This will give him a boost table to write to.

Griswald

Junk the mefi1 and the boost-referenced regulator. Crate Engine Depot has a brand new mefi4a with harness for just over $600. You can probably bring the fuel pressure down to 50lbs or so and raise bpw enough to get the afr you want without killing the injectors. I did this on my old 502mpi and never got over 60% on the duty cycle at 6lbs of boost.

skydog

Yea man that baby is lean!!!!! Give her some fuel asap!!!!! I would not run until I did....

Trash

Several points which echo previous comments.

42 lb injector is not enough. I run 42 lb on a N/A small block.

MEFI 1 is ok for NO BOOST applications. It is simplistic and lacks fidelity but is robust and works. I would follow Griswalds advice RE the MEFI 4.

In my opinion, 13.0 at 5000 rpm and boost is too lean. For reference I'm 12.5-12.8 WOT naturally aspirated (5000-5600 rpm).

You can get bigger injectors to fit the MP/EFI. RC injection is one vendor. I'm sure others will chime in for other sources.

Best of luck.