Setup for injectors characteristics

SCIROCCO53 · Post by **SCIROCCO53** » Fri Feb 17, 2006 9:48 am

What is the best startup value for injectors?

MS-I V3 manboard, MSnS-E 24s13c, low ohms injectors (Audi s4 inj 346cc), Etanol E85 1900cc engine with superscharger and 10-12psi boost.

ochizon · Post by **ochizon** » Fri Feb 17, 2006 9:51 am

dont your injectors fire 4 times per cycle?
(4 cyl engine?)

SCIROCCO53 · Post by **SCIROCCO53** » Fri Feb 17, 2006 10:41 am

ochizon wrote:dont your injectors fire 4 times per cycle?
(4 cyl engine?)

Why should I inject 4 times per cycle? the engine only fire one cyl per cycle

78Spit1500Fed · Post by **78Spit1500Fed** » Fri Feb 17, 2006 12:55 pm

A 4-cylinder motor will fire all four cylinders per cycle (720Â°)

Regardless of the settings in the window shown above, the entire quantity of fuel required for a complete cycle will be injected in that cycle, regardless of the number of times it's injected.

What I'm getting at is that is if the REQ_FUEL is right, the motor will run regardless of how many times it squirts or if it's alternating or simultaneous.

How the motor will run BEST is determined by your specific upper/lower intake/valve head/combustion chamber/injector placement. These settings you can play with to find the best of the best!

-Brian

ochizon · Post by **ochizon** » Fri Feb 17, 2006 4:29 pm

SCIROCCO53 wrote:
ochizon wrote:dont your injectors fire 4 times per cycle?
(4 cyl engine?)
Why should I inject 4 times per cycle? the engine only fire one cyl per cycle

isnt a cycle 720 degree rotation on the crank? The engine fires a cyle every 180 degrees of the crank. That means all 4 cyl fire once per cycle (if I am right about the 720, that is...)

Can someone verify/negate?

78Spit1500Fed · Post by **78Spit1500Fed** » Fri Feb 17, 2006 6:23 pm

ochizon wrote:isnt a cycle 720 degree rotation on the crank? The engine fires a cyle every 180 degrees of the crank. That means all 4 cyl fire once per cycle (if I am right about the 720, that is...)

Can someone verify/negate?

Yes. A four-stroke even fire four-cylinder motor fires all four cylinders in one 720 degree cycle. (180 degrees between each cylinder's compression stroke.)

-Brian

SCIROCCO53 · Post by **SCIROCCO53** » Fri Feb 17, 2006 11:24 pm

But about the PWM settings?

Copy from: Tuning Your MegaSquirt

"If you have low impedance injectors (less than 4 Ohms), set the:

PWM Time Threshold to 1.0 msec, and
PWM Current Limit to 75%(30% if you have installed the 'Flyback Board' daughter card)."

"Note that with port injection, you must choose at at least 2 squirts per cycle with alternating injection, otherwise every other cycle for each cylinder will get NO fuel! The engine will run very badly."

78Spit1500Fed · Post by **78Spit1500Fed** » Sat Feb 18, 2006 8:21 am

SCIROCCO53 wrote:But about the PWM settings?...

I think you answered your own question:

MegaManual wrote:"If you have low impedance injectors (less than 4 Ohms), set the:

PWM Time Threshold to 1.0 msec, and
PWM Current Limit to 75%(30% if you have installed the 'Flyback Board' daughter card)."

What is unclear about this instruction?

Your original post says:

SIROCCO53 wrote:MS-I V3 manboard, MSnS-E 24s13c, low ohms injectors (Audi s4 inj 346cc)

I don't know what "low ohms" means, but the settings are right there in black and white.

-Brian