johnhup or other MS 02er...MS question

[jakeb]

What is your PW at idle?

I am a little confused on what that should be at..

I have my car idling but want to get a little smoother before I continue to tune.

I have been reading and reading and can't understand how the REQ_Fuel connects to the VE and the PW and cranking PW, etc etc

i like to understand and not just type in numbers.

thanks,

Jake

ob btw, it shuts off now after adding the diode.

[73_02]

Thread hijack, not really I do have a question for johnup, how much dinero did you spend on the squirt setup, it looks like one of my cars needs it.

[johnhup]

What is your PW at idle?

Its been a while since I have been working on tuning. I am getting my spark control setup shortly and then I will really begin to fine tune. Check this link on YouTube. Its a video of my computer screen at idle and with a few revs:

Hope that helps.

[johnhup]

It has cost me about 2,500 in total so far. I did a lot of other upgrades at the same time so its kinda hard to remember (they were all MS related). Some things I didnt need but I bought them anyway like TWM spun air horns, a new crank pulley, tii booster, etc.

Im not even done with the project yet either. I would comment more but its hard to say until I get spark control going. JimK or Lee could comment further as they completed their setups way before me.

I am still getting low-end hesitation due to the nature of side-drafts, ITB's etc. I am getting so much fuel and air in off idle I need a steeper spark advance curve. I should have that done in a few weeks and I will post my findings. As for the high end, it screams!

[johnhup]

I have been reading and reading and can't understand how the REQ_Fuel connects to the VE and the PW and cranking PW, etc etc

Read the Manual... over and over. I read it on the bus, and at work until I understood it enough to get it going. That being said, I still had questions too.

Required fuel is directly correlated to pulse width. The computer has to know how much fuel is required (based on VE) and how long (PW) to hold open injectors of a given rate (pounds).

So, if your motor is too big and your injectors are too small the MS will want to hold open the injectors longer but it has a limit. (I think MS's PW limit is 26ms or something like that?). Transversely, if the motor is too small and the injectors are too big it may have a problem idling (there is also a lower limit on PW).

[cowlum]

dont quote me on this - I only got my megasuirt going in the last month and although it runs it still needs tuning.

As far as I understand - The Volumetric Efficiency table represents the amount of air the engine is capable of pumping through itself. The required fuel is the size of the PW required to supply a single cylinder fires worth of gas at 100% effeciency (the engines peak power). The pw is the length of time the injector stays open determined by the current Volume Effecency of the engine (and a few other variables). ie if the car is at idle then the PW should be quite small as the engine is not even close to maximum effeciency.

I may be completely wrong btw!!!!

My megasquirt totalled 600US (nz 1200) so far! but then its made out of all junkyard or free parts. Injectors took me three months to find. And just last week I pulled an EDIS system which i thought i would never find here in NZ with all out jap cars.

[Pinepig]

I am still getting low-end hesitation due to the nature of side-drafts, ITB's etc. I am getting so much fuel and air in off idle I need a steeper spark advance curve. I should have that done in a few weeks and I will post my findings. As for the high end, it screams!

Try opening your spark gap a bit, I had a little stumble on mine with the gap set at 28, set it to 38 and the stumble went away.

[PSloan]

With those big injectors it's going to be hard to get a nice idle/

[johnhup]

I am still getting low-end hesitation due to the nature of side-drafts, ITB's etc. I am getting so much fuel and air in off idle I need a steeper spark advance curve. I should have that done in a few weeks and I will post my findings. As for the high end, it screams!

Try opening your spark gap a bit, I had a little stumble on mine with the gap set at 28, set it to 38 and the stumble went away.

My plugs are gapped at nearly 40. The problem due to the VE being so high at such a low RPM due to the ITB's. Spark advance will solve that.

Ever been in a car with sidedrafts and a dizzy? The low-end isnt that great either.

[jimk]

[quote name="johnhup

So' date=' if your motor is too big and your injectors are too small the MS will want to hold open the injectors longer but it has a limit. (I think MS's PW limit is 26ms or something like that?). Transversely, if the motor is too small and the injectors are too big it may have a problem idling (there is also a lower limit on PW).[/quote]

To add to what you said, the max time open is limited by the duty cycle time. Attached chart gives the max time available and is a function of rpm. Not supposed to exceed 80% of available time for the injectory duty (or PW) or the injector coil will overheat.