MJY100460 Injector flow rate
Turbo Mini Forums

I've just had my injectors cleaned and flow tested by www.injectorcleaning.co.uk.

Posted them on Monday, back this morning Wednesday - Brilliant Service.

They are the MJY100460 as used on the MPi Mini and some other Rovers, such as the 620 Turbo.

Anyway, they flow tested them and the result is 122cc in 30 secs at 50% duty cycle.

This equates to 488cc/min, which is more or less what we thought, but good to have confirmed.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Do they do opening time measurements? And how much difference in flow between the different injectors?

Jean

http://www.jbperf.com/

They quote 3ms open then 3ms closed for 30 seconds.

I would imagine that they have a built in opening time in the cleaning/flow measuring equipment. It must be close to the 1ms measured by TD, else the figures would be way off.

After cleaning, three were at 122cc and one at 121cc. That's good enough for me.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

How much did they charge you Paul?

Their standard charge for top feed injectors is £10 plus vat each plus postage - about £52. There is also the £6 to post them off.

A lot maybe, but I don't want dodgy injectors fouling up the Megasquirt trials.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

The the results are inclusive of open/close time. Very few 'calculators' or flow measuing takes into consideration the open close, they just measure or calculate the result

This is a highly talked about subject on other forums, some even say to set open times to zero and tune it with the VE map.

Unless the characteristic of the injector changes, the open close time will remain the same so why do wee need to consider this, unless you run pulse widths close to this open time

When they test the injector, it is pulsed with 13.8v at 3ms intervals, so if there is 0.9ms open and for argument sake the close time is 0.9ms, the injector was full open for 1.2ms the results are inclusive of open close time.

I spoke to my Mapper about open close times and he gave me a blank look, he said that most systems learn the open close times, but i suspect they just tune the VE map with what would be a zero open time.

Any one with an Emerald system want to confirm this, what settings are there for the injectors? A screen shot would be nice LOL, my mapper will not tune or deal with anything Emerald as he fell out with Dave Walker many years ago over a public slagging match in CCC magazine, sounded quite a heated argument.

If you open and close and injector for 3ms and it flows Xcc why does it matter about the open close time?

Edited by Sprocket on 9th Jan, 2008.

The importance of the open/close time is the fact that it is dependent on the battery voltage. So if you "tune" it with the VE map and the voltage changes, then your tune is off, especially at small pulse widths.

Also, if you have staged injection, you need to consider the open/close time to correctly make the transition unless you use 2 separate VE maps for the 2 staged injectors. But then it because a much bigger task to tune correctly.

I suppose that if your battery voltage is very constant and you have a single injector per port that you could "tune out" the open/close time with the VE map. You'll always have voltage variation during cranking but that may not be a big issue. I wouldn't do it that way because it doesn't seem very accurate and predictable to me. Also, if you need to change injectors at some point, you're screwed. Your previous map could be almost useless.

Jean

http://www.jbperf.com/

All valid points.

Big question is however, how do most people decide the ramp up time is the correct one.

We know the ramp up time for the MJy100460, because of Daves worthwhile and time consuming experimentation, not all of us can get hold of the equipment to do this sort of testing. So unless the ramp up times are definative, there is still some error involved, but it would be a lot closer than if the ramp up was set to zero.

:)

In a "normal" engine with port injection and Megasquirt, what people usually do is they go from 1 to 2 to 4 injections per cycle and see if the AFR stays the same. If it does, the opening time is correct. If it changes, then depending on which way the AFR went (rich or lean) then the opening time needs adjusting to a smaller or bigger value.

On the bench, you would need some way to inject a fixed number of squirts of a certain duration (a few milliseconds), measure the amount of fluid injected, then inject the same number of squirts of double the duration, measure the new amount of fluid and compute out the opening time. The actual math equation is left as an exercise. :)

Jean

http://www.jbperf.com/

One more thing. On the bench, you would also ideally do the measurements for different voltages so that you could have an idea of the opening time as a function of voltage.

Jean

http://www.jbperf.com/