Emulsion tunbes and EFI

[Mark McClure]

There is a long story to the engine that I have in the car just now. It is a 3.0SC 79 with ITB and EFI from Microtech. This will all soon be changed to an Autronic when I put the new pistons, cam, SSI and monty on.

I have been playing with the setup of the Microtech and have come across the EMULSION Tubes screen ( factory setting ). It can be set to different % at different RPMs.

Here is the question! How can you have an Emulsion tube setting on an EFI setup? Obviously air can not be put into the system, so what effect would the setting have on the operation of the injectors?

Cheers

Mark.....

[jluetjen]

A software kludge to make the programming easier for old fashioned carb guys????

[ttweed]

Yeah, what John said. They probably have a programming tweak to vary pulse width of the injectors over a given RPM range to simulate what changing emulsion tubes in a carb would do. What you need to know is what the entered value does, and only the Microtech manual will tell you. It could be introducing more fuel or less fuel (which is the equivalent of more air) in the given RPM range by changing that value, since emulsion tubes can do both, depending on the level of fuel in the chamber and the size and arrangement of the holes in the emulsion tube.

OBLIGATORY WARNING!! I'm sure you are aware of it, but you need a wideband O2 sensor or an exhaust gas analyzer hooked up to tell you what's happening with the mixture while you make these changes or you could easily fry your motor.

TT

[Mark McClure]

Thanks guys.I have an O2 sensor hooked up with a display in the car.

As it is set up now the car is rich on idle and at cruise......leaning to 14-15 under acceleration. The settings start @ 3000rpm with +35% increasing at 500rpm intervals.

I will play at bit more and see what happens..........the Microtech manuals are crap! and the company is not much help at all.

Cheers

Mark.....

[ttweed]

Originally posted by Mark McClure
the Microtech manuals are crap! and the company is not much help at all.

That's too bad. You know, I e-mailed them a couple years ago and never heard back from them myself. I guess customer service isn't their long suit. I can tell you I've been very impressed with the support from SDS in Canada.

From your description, it sounds like you need to fatten up under load, not necessarily higher RPM. Are you using a MAP sensor input? Increasing those values in the low vacuum ranges may be more effective than increasing fuel w/ higher RPMs (which is what it sounds like the "Emulsion Tube" screen does), if you're going lean whenever you accelerate (regardless of RPM.) You need fuel to be increased immediately when the throttle plates open wide.

If you aren't using a load mapping, then all you are left with is throttle position to accomplish this.

Good luck,
TT

[Mark McClure]

I can use MAP to define the fuel under load as well as TPS. It will take the greatest value. I have managed to sort out the load issue but it is the Emulsion tubes that have me baffled. I suppose that if you did not use the MAP you could compensate with the Emulsion tubes as you suggest.

What info does SDS provide you with regarding the PWR settings? Again Microtch have come to the party with "factory configured"

Cheers

Mark.....

[ttweed]

Originally posted by Mark McClure
... regarding the PWR settings?

PWR? Sorry, I'm not familiar with that acronym. What does it stand for?

The SDS system determines the total necessary injector pulse width by multiplying the load (MAP) value by the RPM value, held in two separate maps. Is that how the Microtech system functions? It sounds like you are saying that the Microtech system chooses the higher of the TPS or load values? It still factors in RPM, too, no? The TPS is not used with the SDS system if the MAP sensor is present, except for a momentary "accelerator pump" enrichment function when the throttle is opened (there's the old "carb" language thrown back in the digital mix.)

The emulsion tubes in carbs basically function as a way to change the "fuel curve" slightly across the load range. It is a more subtle adjustment than changing the jetting. They allow more or less air to pass into the fuel stream at differing loads according to their design. It sounds like it is just an RPM enrichment scheme in the Microtech system.

TT