Another "Is Fuel Injection a Worthwhile Upgrade?" Question

pishta said
There are plenty. Carbs dump fuel no matter what the motor wants via the accelerator pump. The motor basically catches up to the carb then it just pulls what it wants rich or not depending on the jetting. EFI has to catch up to the motor (in feedback loop mode), ie. you mash the gas, the MAP goes down, the car goes lean and the computer has to play catch up metering the injectors duty cycle to get it to stoich (or whatever the tune says) and this is an injector chasing the RPM scenario. Meanwhile the carbed motor is pulling away. Now this sampling happens in milliseconds but EFI are designed to be clean, metering the motor what it can burn. you can tell them to be rich at WOT past what they are supposed to be at but that is the tune not the EFI itself. Many WOT's go out to open loop and override the O2 feedback and now your tune better be spot on as its running blind, computing the RPM with the MAP to a table....keep an eye on the AF guage! Cold starts, emissions, ease of driving...it was an evolution of the carburetor to meet current emissions standards. Start an EFI in the -10 night and drive it away, try that with a choke in under 20 seconds. You cant really carb a motor with a supercharger on it and have it idle all day in traffic with the A/C on, and warranty it for 50K for any driveability issues like the current Hellcats, and Mustangs. High pressure pump is the easiest part. then its about 3-4 sensors and the TB (or MPFI injectors) go bank fire so its only a 2 channel system, no need for sequential-no performance gains there. Batch fire is just TBI closer to the valves as they all pulse at once. If you adapt the Ford EEC-IV with its mass air valve, it self tunes to a stock or slight cam. Lots of older 5.0's still running around with their original ECU's and stock tunes. IT doesnt care what its powering as long as the inputs line up. About half of them dont matter on the ECU plug, ie. transmission temp, what gear its in, A/C, seat belts, etc. Modern bolt ons dont have that stuff and are self tuning too nowadays. Good luck. TBI it and carry a carb and a fuel pressure regulator in the trunk if it makes you feel safer.

The EFI doesn't have to catch up, right in the MS3 and a Holley it allows you to do all kinds of mapping from something that mimics an accelerator pump when you even move the TPMS at all, with ramp outs. So you can do some level of accellerator pump, map dot (change in map over time), and a time based accellerator enrichment ramp out. The carb has zero chance against this. The EFI only needs to be in a feedback loop with a proper tune under a somewhat steady-state mode and it uses a PID controller that you can set the gains on and it will come back and make extremely minor corrections from an already decent table if you tuned it anywhere near right. If your table is smooth it even interpolates between your set points. It's also doing a control loop roughly every 10 ms. You can even have the ECU update the tables every so many seconds even in non-self tuning mode.

It uses MAP, TPS, and RPM to run both the fuel and the spark tables simultaneously. Having had both on the same engine, the EFI is far more responsive always and to be honest I don't even think I have the best possible EFI tune since I road tuned it by myself. It also has a warm up enrichment adder that you can base either on the water temp or the intake air temp, your choice.

When I first installed it, the car fired immediately, I let it idle in the driveway for 15 minutes on self learn and drove around the block 3-4 times then went directly to a cruise in. Remember this is not a bolt on kit either. In under an hour, it was on par with the carb. To be honest most people don't have good carb tuning skills either so even a mediocre tune on an EFI like the self learning TBI styles like the Holley Sniper will probably run a lot better.

I also have a car that doesn't mask fuel/spark problems like an auto with a loose converter would. 6-speed with a 3.23 rearend, you need it to be right. I also drive around at 1400 rpm in 6th which would be hopeless in a carb with this combo. I also get about 15mpg in normal short trip driving.

The accelerator pump in a carb just covers the lean spots before the boosters catch up, which the boosters are always a compromise. Go with too big a carb and it will be extra lazy and need a lot of accelerator pump.

Any good EFI system isn't a 1980s TBI, or really anything from them. The carb will lose with today's systems. If it worked like you say, everyone's turbo car would have exploded a long time ago.