Megasquirt and Big injectors

[Andrew7DG]

If anyone running the MS2 system on their car (doesn't matter if it is 4g63 or 420a) I am just wondering what size injectors are you running. I am having some trouble getting my 1150cc/min FIC injectors to work and I really don't know why.

It just seems too rich right now at idle but that shouldn't be an issue. I just want to see what other people are running.

I am wondering if I should take off the stock resistor pack and use the PWM built into the system to control the injector but I don't know if that is the correct way of trying to solve this problem.

if anyone has any ideas let me know!

 

[Ajax]

I run MS1 with 1660cc injectors I have the low Z injectors with the inline resistors. I have some issues with idling but I think its due to the fact that I cannot control my stock IAC but I am upgrading to MS 2 which can. Give us a little more info on if you are running low Z or high Z injectors and what your engine constants are set for injector characteristics.

 

[silvreclips]

I have always heard that when running big injectors its better to use the PWM to control them.

Have you gotten the car to run on MS2 with smaller injectors?

 

[thilaksharma]

we have a few cars running with big injectors
try emailing my tuner [email protected]
we have two cars running 850cc FIC and one with sard 800cc
im sure he has done bigger ones too
but we faced issues if did not fit the resistor pack

 

[turboglenn]

All injectors are PWN controlled (pulse width modulation) hence why their time opened is called pulse width. The problem with big injectors is that ALL injectors dont' like to fire at anythng under 2.0ms (at least reliably) So when you have to turn them down to .93 - 1.0ms of injection time to idle they will fluctuate in the amount of time it takes to open them, how longg they actually stay open and that's if they do fully open. Fuel pressure also effects this, more pressure on the rail = more "dead time" ...less pressure = less dead time, pressure can effect them to where they either can't get open all the way and you ahve to dial in more pulse (making them a tad more reliable) and some prefer less pressure so they open eaier on the small pusle they get from the ECU, it's a fine balancing act, as idle is one of the toughest things to tune. I can dial in a good full map in a couple hours but I cannot count the time i've spent perfecting and learning idle procedures on big injectors (especially when cams are low vacum and built and degreed for more top end)

I run 1000's on my E6k, MY buddy runs 1600's on his LINK ECU and I've tuned on Ajax's car with the MS and his 1660's.. I would say by far his has been one of the best performing setups for a nice smooth idle and transistion from idle to go. I would listen to anything he has to say about megasquirt and big injectors... Also, running E85 allows more puslewidth at idle making it easier to tune (just an FYI and another reason to switch )

 

[Ajax]

Thanks for the compliment Glenn but you did alot of the tuning so to the OP Glenn is very knowledgable when it comes to tuning. Just giving you a heads up I am also upgrading to MS 2 which takes injector pulse resolution down to 0.67 microseconds compared to 1.0 microseconds with MS 1 and HiRes code. But I will wait to install it before so I get the motor running on MS1 first and then switch to MS 2. Also OP what fuel control do you have, fuel pressure set at? Need to update your profile.

 

[mobythevan]

I think something may be wrong in the statements about injector resolution in hires vs MSII. The Hires code says in the readme it provides about 2.5 times the resolution from MSI for injector control. The MSII upgrade page says it provide 100 times the resolution from MS1. Just a minor detail, but I believe the MSII has much greater injector resolution unless some of it was removed for MSII_Extra functions. Does anyone know for sure? I only run MS1 on all my cars using the hires code so I am not sure.

 

[Ajax]

MS 1extra =100 micro seconds
MS 1extra with HiRes code =1 micro seconds
MS 2extra = 0.67 micro seconds

Thats what I always believed but then again I could be wrong.

 

[mobythevan]

I wish MS1 hires was that good, buts its 33

so 100,33,1 for the three. I wondered because I went from MS1 to MS1 hires and still didn't control the 150pund injectors on my LS1 very well. I think MSII would do the trick though.

 

[Ajax]

Great thanks for the info. The place I bought mine from must have been fudging there numbers a little. I just hope MS-II can handle my 1660cc injectors better.

 

[Andrew7DG]

I have been playing with fuel pressure just to see if that would help me out. I have a Aeromotive FPR. I turned it all the way down to 30 psi to see if that helps out at all. That could be a little too low really...

Then I started to play with the PWM WITH the resistor pack still installed and that seemed to help out a little bit. I saw my AFR come upto 13:5 where they were 10 before.

From MS2exta:

If you are running high-impedance injectors (greater than 10 Ohms), then set the:

PWM Time Threshold to 25.4 mSec, and the
PWM Current Limit (%) to 100%.

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).
You will tune these after getting the engine running. See "Setting the PWM Criteria" in the tuning section of this manual. Failure to perform the tuning steps can result in damage to your injectors. If you have high-impedance injectors, set these values to 25.4 ms and 100%, and you do not need to tune them further.

I have been told that I should set the PWM to the High impedance injector setting because we have the resistor pack inline. However that may have worked for the 450cc injectors. I am thinking these 1150cc injectors are a little more difficult.

I guess the question is then, do I keep the Resistor pack or take it out and let MS2 use PWM? Or can I do both? Use the Resistor pack and the PWM? But would I get any problems later say Higher RPM, higher load?

PS- also trying to tune with a HKS272 cam and has anyone had problems tuning that with lower idle vacuum?

 

[Andrew7DG]

Did a little rewiring today and rewired the injectors so that there wasn't a resistor box between the signal of the megasquirt and the injectors.

I think this work out a lot better.

I also switch to E85 and it idles a lot better then what it did.

This is the best idle that I have ever got out of the system.

 

[kawgomoo]

so how did this work out for you? did you fry anything on the board since you didnt have peak n hold drivers installed?