View Single Post
JFairman JFairman is offline
Registered User
Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
"Then tune around this by increasing in spring tension at the AFM."

Thats the opposite of what I do when tuning L- jetronic for more power.
L-jetronic is similar to motronic, but it's analog, fires the injectors 3 at a time alternating on a 6 cylinder engine, is less accurate and only does the injection and has nothing to do with the ignition.

I loosen tension on the barn door spring in the AFM so it opens easier and farther so the motor breathes easier and injector dwell time is increased for any given rpm and then compensate for the barn door opening farther at idle and being too rich by opening up the CO air bypass screw in the AFM so the barn door closes up and the AFR is correct at idle.
Then install an adjustable rising rate wide band fuel pressure regulator on the end of the fuel rail so you can have higher fuel pressure under acceleration and zero manifold vacuum.
You can also take the stock fuel pressure regulator and take 2 sockets of the right size and squeeze the ends of the metal housing together a little bit in a vise. That increases the spring pressure inside the FPR and raises the fuel pressure, but an aftermarket adjustable vaccum controlled rising rate FPR is wayyyy better.

Along with that I install a 10,000 ohm linear taper potentiometer in series with the engine temp sending unit so you can add resistance to the sensors reading and make the ECU think it's colder out than it is up to 30 below zero so injector dwell time is increased for alot more fuel with the turn of a knob on the dashboard.
Of course there are alot of different EFI injectors to choose from but I never turbocharged a car with EFI so didn't need to.

I love the simplicity, accuracy, and adjustability of EFI and I wish CIS was never invented.
Old 01-26-2010, 02:08 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)