I've got a complicated system with a few problems I'm trying to work out. By complicated I mean I'm running a GM based TBI system from Affordable Fuel Injection (they have been almost zero help) on a 1984 Dodge W350 Crew cab with a 360 that has been stroked out to a 410 stroker motor. It can make a lot os HP and torque if it runs right. I have a 454 TB and for sensors I have an IAC, MAP, Temp, TPS. No knock sensor. For ignition I'm using a stock MOPAR distributor (magnetic) with the advance welded and a GM ICU. I've checked it thoroughly for vacuum leaks and I get no trouble codes.
I'm finding my GM TBI system gets worse over a period of a few days... If I pull power to the ECM then reinstall the fuse it runs pretty good for a few days and the slowly gets worse and worse. I get what feels like a lean miss and eventually it backfires on acceleration. if I reset the ECM again it gets better for a few days and then slowly come back to the poor running.
I also have problem with spark advance. If I set my base timing to zero degrees (unplugging the wire) I get lots of pinging right off the bat without even giving wide open throttle...really bad.So I've been running it with the base timing set to about 8 degrees retarded and although the pinging issue is nearly gone, I've also lost most of my power and the mileage sucks. I've tried swapping the ICU with no change. I also pulled the distributor and made sure everything was still welded together (the advance is welded) and nothing was sloppy or loose.
I do not know what my injectors are and the folks at Affordable have no idea what they sold me either (jerks), BUT I took them to a place in Gladstone and had the guy flow test them. He said they are both even and have a nice pattern, BUT they are huge injectors...they tested at 180 at every pressure he put through them. I am running 26 psi fuel pressure (that's the way it was setup when it came).
I hate simply swapping parts....so I'm trying to get some advice on what my problems might be. I believe I have a couple of them at least.