[olddog]

To all:

I'll explain what I have and my issues and maybe you can give me some pointers.

I have a 347 stroker with a big bump stick in it. The fuel injection is sold by MassFlow. It was on the car, when I bought it, and the previous owner bought the MassFlow system used. It has 36 lb/hr enjectors and I think the throttle body (designed to look like a 4 barrel carb) is about 1200 CFM.

The engine runs very lean when started cold. Exhaust burns your eyes (I originally mistook that to be rich). The idle is low and engine hesitates and wants to stumble. When the O2 sensors heat up and it goes into closed loop, it runs good. However it does not make the power that it should. I have removed power to clear the memory and got the same results.

I have talked with MassFlow, and they have been very helpful. They will chip the EEC and do a tune for my engine at a reasonable price. However I do not like the idea of a tune based on theory. I feel a dyno and exhaust analizers is the only way to know if you have it right or if a sensor is off.

My engine started running rough below 2000 rpm and then it tripped a code for a bad O2 on the left side. I could tell it was running too lean after this. I pulled the O2 sensor out, and it is snow white.

I have verified the TPS is good and the votage is correct at idle. The water temp sensor is at 29.7 K ohms and the manifold air temp is at 29.4 K ohms, with a cold engine at about 80 F. This matchs with a chart I found on the net, so I believe both temp sensors are good. I have turned the fuel pressure up to 46 psi to help with the cold idle issue, but do not want to do this long term. So I figure either the mass flow sensor is not reading correctly or something is not mapped correctly in the tables.

Ok as I try to read and learn more about all this, I have learned that maximum power is made at an air fuel ratio of 12.5:1 and that the O2 sensors cannot read very far from 14.7:1. So at WOT the EEC goes to open loop to richen up the mixture to make maximum power. Since my system is running, lean when in open loop, I think this is what is killing the HP.

There are lots of chassis dyno around me, but so far only one has come across as knowing half of what he says he knows, the rest have not inspired me. I want to at least learn more and at best get it running as good as I can, before wasting time on a dyno.

Am I thinking and doing the right things? More advice is welcome.