HILBORN PROBLEMS

[GASSER 48]

Have a 496" BBC in my '55 Chevy Gasser. Orginally had a Holley 4 barrel and it ran fine. Bought a Hilborn electronic fuel injection and it wasn't cheap. Since I installed last Sep has never run quite right. Now it's gone to shit and is running way rich. Working with Hilborn tech for over a week and still ain't fixed. It uses a Holley ecu and harness. Anybody have any experience with a Hilborn system on your engine.

[chevynut]

I can't imagine that the Hillborn EFI is much different than any other EFI setup. Did you program it or did it come as a pre-programmed kit? Are you using the Holley C950 ECU or something else?? I would suspect either a bad sensor or your program needs to be tweaked. Did you have it tuned since you installed it? Since it ran better before, it seems to me a sensor may have crapped out. You should be able to check out the sensors with a laptop.

[GASSER 48]

Not sure model # of Holley ecu. Hilborn tech sent me a program to load. Initially did not have self learn enabled. Fixed that and ran fairly good. Some minor issues with slow start and idle. This thing has barely any miles on it but guess it's possible the o2 sensor is bad. Did datalog and found that learn table showed running way to rich, so points to 02 sensor sending incorrect msg. ECU cleared, reloaded, and restarted engine. Runs O.K. and learn table shows all zeroes.

[Rick_L]

I'm no expert on this, but there are a couple of things that might be up, though if you got the system from Hilborn they should have been taken care of.

1. There needs to be a balance tube that connects below all 8 throttle bodies. The MAP sensor should be connected to it. You might check for a vacuum leak on those connections. Check the MAP reading on your data log.
2. All 8 throttle blades should be synch'd up and delivering the same amount of air with the blades closed (they should have done that for you).
3. An exhaust leak can screw up your O2 sensor readings. If "false air" is entering the exhaust tract, your O2 sensors will show lean and then the controller will richen the system unnecessarily. Temporarily disable closed loop and see if that helps.

That's just a start.

If your computer has a learn mode, then it's the newest version, either an Avenger, HP, or Dominator, as opposed to a C950. It's probably an HP.

[GASSER 48]

There is a vacum fitting (8) at the bottom of each throttle body. They all route into a single block. That's where the MAP sensor is attached. Checked for vacum leaks and all good. When first installed did all the sync stuff per factory instrs. with flowmeter. No exhaust leaks and recently installed new header collector gaskets. When laptop connected and engine running I monitored all sensor input readings. They all look normal. Holley and Hilborn techs think it's the o2 sensor. So ordered new one and should arrive today. Just seems a long shot that an o2 sensor would go bad so quick, but guess it can happen.