Engine Management, Do we really have to keep it???

[Z3_GoCar]

Here's some blue sky thinking, so I don't want anyone to take it personal or anything....

So my thinking goes like this...

Engine mangement has two basic functions:

1) spark timing and control and

2) fuel timing and control.

Let's address the, spark timing:

1-e authorizes any ingnition system, including crank fire systems, if originally fitted. So, if the engine management system had a crank-fire type system, that function may be taken away from the stock/replacement sytem in the oem housing. Funny seems to be in direct violation of 1-a-6, no piggyback computer or additional wiring. How about when Joe adds a MSD box. Isn't he adding a piggyback computer to his distributer with it's associated wiring?

I'm still thinking about the fuel side of the issue, but I have an idea of another contradiction that may open this up too.

[Jake]

Thing about MSD is that it doesn't change the ignition timing. Not all that smart.

[JeffYoung]

Guys, an MSD is not a "computer" per se. It's basically a capacitive discharge system. All it really does is increase the power of a spark.

I do agree that the rev limiter function on the MSD (which is run off the distributor) goes beyond this and may be a (bit) problematic. But if anyone is getting their panties in a wad over the rev limiter on an MSD, they are barking up the wrong tree.

There are some long studies on the web about what an MSD will and won't do for you. Basically, the idea is that for FI systems that already have very precise fuel/air mixtures, the MSD doesn't do a lot. The extra spark isn't much help because a decent stock ignition with a good management system will make sure the juice gets all fried up nice.

But, where you start to see some advantage with teh MSD is on carb cars where the fuel air mixture is imprecise. MSD and its added spark here can really help.

I had a nasty miss in my TR8 when I first started running it. WOuld not pull cleanly to 6k. I changed a bunch of things at once (rebuilt the carbs, coil, and MSD), but I think the MSD helped cure the issue.

Of course, where the computers on EFI systems really help is in maximizing torque and hp UNDER the curve. Claims of 20 hp on the top end usually don't pan out, but look at what maximuming on a 100 rpm increment does for overall hp and torque. That's where the big gains are for the computer cars, and the MSD really hasnothing to do with that.

[Z3_GoCar]

Thing about MSD is that it doesn't change the ignition timing. Not all that smart.
[/b]

Yes, but a distributor can be blueprinted. With OBDII you can't mess with spark timing in any way, the computer will just adjust it back, it's got to do with internal trade secret check sums, that keep you or I from messing with the system like you can do to the distributor type system.

Second part of my argument is that OBDII keeps you from performing a the perfectly legal function of adjusting the mixture. If you're stuck with a non-adjustable carb you're allowed to swap to an adjustable replacement carb, but if you're stuck with a non-adjustable computer system you have to shell out the big bucks to replace it with something that can fit in the stock housing, use the stock sensors, and connect to the stock connector, all of which means big $$$ because for different makes and models each of those parts are different. Get the engine management out of the box and allow standalone's.

James

[shwah]

From where we are today, I don't have much resistance to ECUs. However, there have been several systems over the decades that seemed hard or impossible to fool. Folks do figure out ways to get the fuel and/or timing they want. Sometimes they are crude methods, and don't work well over all revs, but they only need to work at race speed for us.

But yeah, an ECU change would be nice for a car like yours, and the box around the board won't change how it functions.

[stevel]

With OBDII you can't mess with spark timing in any way, the computer will just adjust it back, it's got to do with internal trade secret check sums, that keep you or I from messing with the system like you can do to the distributor type system.

Second part of my argument is that OBDII keeps you from performing a the perfectly legal function of adjusting the mixture.
[/b]

That's a blanket statement that's not necessarily true. Maybe for the BMW crowd, but there are plenty of OBDII cars out there with aftermarket options that allow full tuning of A/F and timing parameters and more.

s