Cheers guys. Excluding reliability for a bit, what performance difference would a new system have over original working system? Fuel, mapping (is that even possible on the original ECU?), torque range etc I'm hoovering up knowledge, so don't be shy .
I thought not, but good to get that confirmation. My slight worry with the Californian version ECU that I have, is that it is set up with the assumption of some recirculated exhaust from the exhaust gas recirculation EGR. I understand that this could mean that without the extra hydrocarbons, it might run lean?
No idea. If you were updating the FI system, you wouldn't use an original ECU anyway. Things have moved on!
FI and carb engines use different cams . A modern ECU is tuned to your engine plus it uses a lamda sensor to get the AFR perfect along with crank fire trigger to do away with distributor . Modern Coil per plug plus it’s infinitely more tunable will make more power plus 100% more reliable
OK, so not much then My engine was originally an FI and that's why I'm toying with the idea of converting it back and.collecting the old.parts. I should have asked this question a couple of years.ago...doh Hmmm now what to do without spending stupid money?
Exhaust gas is being used in EGR as inert gas so its really added to make idle cleaner by being able to idle at the same speed while burning less fuel. The brains of a stock EFI is all in that resistor track with its laser trimmed voltage ratios hooked up to the air damped heavy weighted flap in the AFM.. Modern EFI can use just about any combination of sensors to provide injector control. Not all of them are as perfect as any other. Adding a throttle position sensor, and a manifold air pressure sensor or a mass air flow sensor, and picking up a distributor points pulse would be enough to drive a Speeduino ECU or a MegaSquirt ECU. Things like lambda sensors are great for tuning but in fact you could set the whole thing up without them in the EFI control loop, although you would really still need one for checking it works properly
why does every modern car have a lambda sensor if it’s not needed then ? The only sensor I’m not running is a knock sensor , and I would if it was an easy do .
For adjustment .. when at a steady state. But when you are accelerating , certainly the well documented ECUs go go open loop because of the time lag between the engine and the sensor. And the lambda sensors are also used to make sure the catalytic converter is fed enough fuel to keep the fires burning.. After all the stock EFI did not have a lambda sensor just an analog computer controlling the injectors triggered by the ignition and controlled by the AFM flap and the angle to voltage map created by the laser trimmed resistors.. And the CIS (K-Jet) just has an air flap controlling needle valves feeding the injectors, with the inertia and overshoot of the heavy balanced flap mechanism taking over the job of feeding more fuel on acceleration.
That’s why I’ve gone all new and modern I can’t be arsed with worn out second hand parts from the 70s . Populate your tables on your laptop and drive
Some good food for thought so thanks peeps. As I have most of the original FI parts, I hope to build a bench engine mount and sometime in the future drop the engine, swap the Weber's to the FI system and see how it works on the bench for starters. I'm not adverse to change, hence my questions but I do wonder if once you change one thing do you butt up against the characteristics of the next item in the old system and start a cascade of change? With that in mind, what one part of a standard FI kit would you change that would make a marked difference? I do worry about the AFM, but that's because I know a bit about it, but am I thinking about the wrong link in the chain.
