Wide VE numbers

[krm57]

Hi, I am a complete

I am running MS2 on V3 board with 2.9 code Tunerstudio 2.0.6 with CBR600RR injectors at 40psi. Running an 875cc 4 cylinder petrol engine.

Trying to tune to acheive AFR between 13.0 and 15.0 at low kPa.

VE numbers vary from 1 (or 0 if it can) to 350 using VE Analyse live. VE table only goes to 255 though.

I have tried to increase required fuel by reducing the injector flow number in the calculator from 19 in steps all the way down to 5 but still requiring very large numbers at 95 kPa. Is there another way?

The car will drive and can run smoothly at low RPM. I have only gone to 3000rpm so far.

Anybody suggest what to do to acheive sensible VE numbers?

Thanks Keith

[Matt Cramer]

Could you post a copy of your MSQ file and a data log of the engine running? This will give us more to go on.

[krm57]

2012-10-20_13.11.53.msq

Hi, Thanks for the quick response. Its probably me being stupid and not understood something as your instructions are really good.

Anyway, here is one of the msq files showing the setup.

Thanks again
Keith

[Matt Cramer]

You have the injector opening time set to 4.0 msec; where did that number come from?

[krm57]

The start up process, start at 1 and increase till it starts. Seemed to work, just luck? Is this a parameter that should relate to the injector spec?

[Matt Cramer]

The start up process, start at 1 and increase till it starts. Seemed to work, just luck? Is this a parameter that should relate to the injector spec?

Please post a link to where in the manual it says to increase the injector opening time until the engine starts. I could not find any point in the manual where it said to do such a thing. This is NOT good practice and will end up completely ruining the VE table if this number does not match what the injectors are really doing.

Injector opening time is actually the amount of dead time - take the pulse width time and subtract the amount of time of actual flow you get, and that's the number the opening time should be. Here's how the manual describes this number:

Injector Opening Time (ms) (InjOpen) is the amount of time required for the injector to go from a fully closed state to a fully opened state when a 13.2 volt signal is applied. Since fuel injectors are electro-mechanical devices with mass, they have latency between the time a signal is applied and the time they are in steady-state spraying mode. Typically, this value is close to 1.0 milliseconds. Note that the closing time should be subtracted from this value, but it is generally very small and can be neglected.

The way the MegaSquirt calculates fuel, the Injector Opening Time setting also becomes your minimum pulse width. If you've used it as a substitute for your cranking pulse width setting, it is possible to increase this number to beyond the lowest pulse width you actually want at idle, thus making the engine untunable until the problem is corrected.

[krm57]

Hi,

Yes thats what I have done substituted the cranking pulsewith for the injector time.

The injector opens 125 times a second so does that mean I should have .8 as my pulse width time?

I was confused as I cant see a cranking pulse widths tab, where is this? Warmup enrichments?

Thanks
Keith

[krm57]

Sorry, have found it and set up properly with .8 and its a lot better now. will start tuning properly now.

Thanks for your help.

I do think that your instructions are great, its all my fault for not looking down to the bottom of the warm up page.

Thanks again
Keith