This page is about sequential injection.
Sequential injection does not give you more power. It gives slightly better efficiency and emissions (in the lower end of operation range, namely idle and cruise) if tuned right. Tuning is finding the small angle-range for injection that needs slightly shorter injection pulsewidth (less fuel) for the same output. See AutoTune? for more info. It's not likely that it can be found by pure calculation.
A good sequential injection system needs:
- a number of injdrivers (like 8 on GenBoard/VerThree, there was only 2 on GenBoard/VerTwo: guess how many will be on v4 :-)
- precise cam-position information, not a (varying phase!) output signal from an ignition module (the fuelrail pulsation problem is solved without this, but I'd call that semisequential if timing is not tunable or tuned properly).
- firmware that supports it
The first can be done on any system that has additional IO (motorola megasquirt does not have AFAIK, although some multiplexing would be possible.) GenBoard/VerThree is your friend.
About sequential compared to batch.
The most important difference is that a batch fire injection system open the injector at least one time per turn of the crank. Sometimes one time per spark. A sequential system only open the injector once per turn of the cam. If we need 2ms of fuel to bee feed into the cylinder the Sequential system will squirt one 2mS squirt, a normal batch fire system would fire 1 mS squirts and the primitive systems that open the injector for each spark would squirt 0.5mS four times(on four cylinder).
At the other end sequential is also superior. Everyone know that you shouldn't use the injector to more then 80%, this is a bit on the safe side but 90% is a good rule when you can monitor duty. Good injectors can safely do 92-94%. But in any case it's not the duty that is the problem. The injector need a certain time to seat properly, this makes the max duty rpm dependant. Since the injector on a batch fire engine see twice the rpm compared to the one in the sequential system the sequential system will be able to squirt more fuel then the batch fire system through the same injector. The batch fire system will also cause nasty pulsing in the fuel rail, it's not uncommon that a car maxing out its injectors with a batch fire system can manage with only 70-80% duty with sequential injection.
Sequential injection is a sensitive area, not many people agree on the advantages.
Some say that sequential injection will not affect the maximum power of an engine; the most common phrase is �The injectors are almost fully open at full power anyway.� This is true in most cases and it effectively makes it impossible for it to make a difference.
Some say that sequential injection can give up to around 4% more power. To mess things up further there are two opposite ways to set up sequential injection for maximum power;)
With a really big injector you can inject all the fuel at an open valve. That way the fuel will be injected in liquid form, which leave more room for air. It seems like this is more or less taken as a fact by most American tuners. Given that most American V8�s burn the fuel it need and dump the rest, this is probably true! The fact that almost all aftermarket cylinder heads are for American V8�s the best 2 valve designs around are found on V8 engines. Swirl heads is also better then tumble heads for a complete burn, not to mention that ALL race V8 engines have a very strong ignition system.
The opposite is that by injecting all fuel on a closed intake valve it will heat up, evaporate and burn better. With a tumble engine (4v-5v) or other engine that like lean mixtures this is probably true.
At low to mid load I think that most people agree that injecting at a closed valve is best for emissions and fuel economy.
When designing a full sequential injection system it�s good to keep the injection endpoint the same when the pulsewidth change with load. Being able to map the end point with load and rpm is important for many engines. The only logical reference is the TDC in the compression stroke.
I have picked up a two ways to find a good starting value for the injection end point but I haven�t tested either way yet.
With the engine idling, change the injection end angle back and forth from 0-720 degrees while listening to the engine. You will find two rough spot, choose the roughest and take 50 away from that value. For WOT you will need a dyno but 40degrees less then the idle value was said to be a good start.
Another way to do this is to find the place where the engine idles smoothest, seeing a richer value on the wideband at this point is a good indication. The same guy said that adding 10-20degrees per 1000rpm usually works well. This should indicate the different approaches, as it�s pretty much the opposite of the other way to tune it�
Some people tune for the leanest indicated mixture, which is logical as more air is what we want. But some tune for the richest indicated mixture, which is also logical! The lambda sensor only measure burned fuel,
A program visualizing a full sequential injection timing.
Injector inductive kickback information
Introducing the Ford PlugAndPlayEEC
- One of the major tuning questions, is injector timing position in the intake cycle.
- EECpnp needs to insure (any special reason? eg. would it fail with batch injection due to fuelrail pulsations?) that the AVR does indeed have delay control capability, to delay from TDC to 45 deg ATDC on the intake cycle, at least under a nominal ~3K RPM to idle.
anyway ( Awesome! )