Megasquirt idle pulsing
idle pulsing
Well I have gotten my 12a turbo with autonimics 4 barrel tb 460cfm with 4 52lb injectors (tbi) at 15psi, lightened flywheel and msd running but the idle is pulsing really bad once the motor is warmed up.
At first i thoguht the motor was leaned out massivly at operating temp. but through various adjustments the pulsing never stopped
I also thought a gasket was leaking so i remounted the manifold and tb and was fine
I know the injectors are big for this setup so i am torn between to choices
I could buy new smaller injectors but for my tbi setup
or i was contimplating only injecting gas in the primaries and using air only in the secondaries
I am uncertian that it would work due to the fact that it might not spread the mixture throughout the chamber
Any injector reccomendations for this setup would help
another question is the low pressure keeping the injectors from operating properly since they are designed for port
one more question is is there anyway to inject oil using the omp into a 4 barrel tbi setup
the closest i could think of would be through vaccum ports on the tbi
premixing with luccas 2stroke dosnt seem to be keeping my motor happy
but hey at least it runs!
At first i thoguht the motor was leaned out massivly at operating temp. but through various adjustments the pulsing never stopped
I also thought a gasket was leaking so i remounted the manifold and tb and was fine
I know the injectors are big for this setup so i am torn between to choices
I could buy new smaller injectors but for my tbi setup
or i was contimplating only injecting gas in the primaries and using air only in the secondaries
I am uncertian that it would work due to the fact that it might not spread the mixture throughout the chamber
Any injector reccomendations for this setup would help
another question is the low pressure keeping the injectors from operating properly since they are designed for port
one more question is is there anyway to inject oil using the omp into a 4 barrel tbi setup
the closest i could think of would be through vaccum ports on the tbi
premixing with luccas 2stroke dosnt seem to be keeping my motor happy
but hey at least it runs!
Rotary Enthusiast
Joined: Jun 2002
Posts: 1,058
Likes: 0
From: Yokosuka
Hey, I got an autonomics TB, but I haven't installed it, yet. Too many projects going at once.
Post up some pics, we'd all like to see the setup.
How is the idle behavior? Does it constantly rev up and down from like 800-1100, or does it idle at 800 then just dip down to 500 rpm and come back over and over randomly? Only does it warmed up? I don't think your injectors are that big for this setup. Sounds like your AE is wearing off so you need a richer idle and leaner AE numbers... At least, it is a place to start again.
The ports on the side of the TB are good for OMP hookups. They should be straight vacuum. You will need to fab a custom rod for actuating the OMP, though. You are using the 12a front cover and not the gsl-se, right?
BTW, your setup is not TBI. That is GM stuff where the injectors are above the butterflies.
Post up some pics, we'd all like to see the setup.
How is the idle behavior? Does it constantly rev up and down from like 800-1100, or does it idle at 800 then just dip down to 500 rpm and come back over and over randomly? Only does it warmed up? I don't think your injectors are that big for this setup. Sounds like your AE is wearing off so you need a richer idle and leaner AE numbers... At least, it is a place to start again.
The ports on the side of the TB are good for OMP hookups. They should be straight vacuum. You will need to fab a custom rod for actuating the OMP, though. You are using the 12a front cover and not the gsl-se, right?
BTW, your setup is not TBI. That is GM stuff where the injectors are above the butterflies.
Rotary Enthusiast
Joined: Oct 2001
Posts: 1,022
Likes: 4
From: Ontario, Canada
SPERRYsan,
Often a hunting idle is due to incorrectly tuned VE table in the idle area. If the idle area is a bit lean, it'll stumble, rpm will drop resulting in a new location VE value (now at lower rpm, higher map) that may result in richer operation, allowing rpm to recover again. Sounds like you have checked this thoroughly, though, so let's look at some other options.
Are you batch-firing all four injectors at idle? If so, your idle pulse width is likely very low, with poor tuning resolution due to the 0.1ms increments in pulse width. Here's a couple options you could try:
1.) Switch to the hi-res code. This new code variant allows much smaller steps in pulse width, and users with big injectors have reported much improved idle quality. Link to thread here: http://www.msefi.com/viewtopic.php?t...ighlight=hires
2.) Wire two injectors as primary, the other two as secondaries, and enable staged injection in the MS code. This will fire primaries only at low load, and switch over to all four at higher load. You choose the transition method (rpm, map, tps, or combo). This mod is best suited to a progressive throttle body. See below.
3.) Is your throttle body progressive in nature? If not you may want to check into that possibility with your throttle body. If there is only a tiny amount of air flowing through each of the four runners at idle, it's quite possible the fuel being squirted ends up settling on walls of the intake, and dribbling into the combustion chamber. This phenomenon is well known, and will give a nasty idle quality that will clear up if the engine is revved to 'clear it's throat'. Then idle will be clean again for a few seconds, and then slowly deterioriate. Check this site for some details on converting the Autonomics tbi to progressive. http://www.mez.co.uk/turbo9.html
Often a hunting idle is due to incorrectly tuned VE table in the idle area. If the idle area is a bit lean, it'll stumble, rpm will drop resulting in a new location VE value (now at lower rpm, higher map) that may result in richer operation, allowing rpm to recover again. Sounds like you have checked this thoroughly, though, so let's look at some other options.
Are you batch-firing all four injectors at idle? If so, your idle pulse width is likely very low, with poor tuning resolution due to the 0.1ms increments in pulse width. Here's a couple options you could try:
1.) Switch to the hi-res code. This new code variant allows much smaller steps in pulse width, and users with big injectors have reported much improved idle quality. Link to thread here: http://www.msefi.com/viewtopic.php?t...ighlight=hires
2.) Wire two injectors as primary, the other two as secondaries, and enable staged injection in the MS code. This will fire primaries only at low load, and switch over to all four at higher load. You choose the transition method (rpm, map, tps, or combo). This mod is best suited to a progressive throttle body. See below.
3.) Is your throttle body progressive in nature? If not you may want to check into that possibility with your throttle body. If there is only a tiny amount of air flowing through each of the four runners at idle, it's quite possible the fuel being squirted ends up settling on walls of the intake, and dribbling into the combustion chamber. This phenomenon is well known, and will give a nasty idle quality that will clear up if the engine is revved to 'clear it's throat'. Then idle will be clean again for a few seconds, and then slowly deterioriate. Check this site for some details on converting the Autonomics tbi to progressive. http://www.mez.co.uk/turbo9.html
well here is my idle[URL= http://upload.ohshare.com/v/4172524/3rd_run.wav.html]
Im wondering if it is just acting weird because of the 11lb flywheel
Ive tried using staged injection and all and it still acts weird
here is my settings http://upload.ohshare.com/v/558942/3rd_run.msq.html
datalogs http://upload.ohshare.com/v/558942/3rd_run.msq.html
anyone got some other good ideas
Im wondering if it is just acting weird because of the 11lb flywheel
Ive tried using staged injection and all and it still acts weird
here is my settings http://upload.ohshare.com/v/558942/3rd_run.msq.html
datalogs http://upload.ohshare.com/v/558942/3rd_run.msq.html
anyone got some other good ideas
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