Jump to content
HybridZ

Injector Opening Times Spread Sheet


z-ya

Recommended Posts

  • Replies 50
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

  • 1 year later...
Has anyone gotten this info for their car with Supra 440cc injectors? I've got MS1 v3.57 stock motor with these injectors.

As long as you have a similar brand of injector to get some times off of, you should be close enough. It doesn't really make a lot of difference unless you had an existing map with another injector and wanted to minimize the retuning when you change injectors.

Link to comment
Share on other sites

  • 3 weeks later...

I don't know which generation/motor you are referring to, but if you really gotta have the vehicle specific threshold and battery compensation, download AEM EMS software and their basemap for that engine. They check the injectors and it is included in the basemap.

Link to comment
Share on other sites

  • 2 months later...

Hey guys,

 

I have a question about the settings for the 450CC DSM injectors. I know what you state in the spread sheet, but there is some other information floating around for those injectors as well. Namely: http://forums.hybridz.org/showthread.php?p=562900

 

The part I am most interested in is that the other thread states the following:

PWM current limit % 100

PWM Time threshold (ms) 25.5

 

Which does not at all match the spread sheet. Which settings should I trust?

Link to comment
Share on other sites

Use the settings in the table, or use a resistor pack. These are low impedance injectors and have to be run with some sort of current limiting or the injector drivers will overheat and go into thermal overload. Use my PWM settings or a resistor pack.

 

Pete

Link to comment
Share on other sites

I'm running the Ford 440 cc injectors 280-150-400 with resistors. I set the opening time at 1.0 ms, but found that for light throttle (MAP<40) i was seeing the values in the VE table at low rpm going up, even though I had the AFR targets leaning out as well. My suspicion is that as the opening time is really longer so the VE is rising to compensate.

 

Just before our storms here in CO I increased opening to 1.2 ms and did one datalogging session. It did suggest reductions in low MAP VE entries without any in the upper right corner of the table, but not as much as I would have expected. I haven't been able to go out again so need to tune more before I can say with some certainty that this injector needs a longer opening time.

 

My intuition says that the opening time with resistors will be longer than without as the resistors are reducing the level of energy applied to the coil. The idea is that it takes a certain amount of energy to open it regardless of how it is applied. Has anyone else experienced this, or could there be something else going on?

Link to comment
Share on other sites

When you you a series resistance the resistance of you resistor pack plays a big factor in the opening time. When using the PWM you can fine tune the settings to get fastest opening time. This essentially what I've done with the measurements that are in the table. The settings in the table will give you the fastest "safe" opening time.

Link to comment
Share on other sites

  • 3 weeks later...

Doesn't look like you can download the software by just registering. It is telling me "The topic or board you are looking for appears to be either missing or off limits to you".

 

If you already have the software, can you send me the entire injector list with electrical characteristics?

 

If they are generic injector characteristics, I will add them to my table.

 

Thanks,

 

Pete

Link to comment
Share on other sites

Doesn't look like you can download the software by just registering. It is telling me "The topic or board you are looking for appears to be either missing or off limits to you".

 

If you already have the software, can you send me the entire injector list with electrical characteristics?

 

If they are generic injector characteristics, I will add them to my table.

 

Thanks,

 

Pete

They aren't in a spreadsheet form, but rather in each individual basemap. Last I checked, you D/L the software and, as an option, D/L all the basemaps. You have to open each one and look at the settings.

 

However, getting the exact minimum injector pulsewidth is largely irrelevant if you already have a tuned car in all but the most basic standalones (of which Megasquirt is not) or if you have a horribly large injector set. I have personally set up 1200 cc injectors on a 2L 4cyl without having the exact pulsewidth. It simply helps when crafting a rough map when first setting a car up.

Link to comment
Share on other sites

They aren't in a spreadsheet form, but rather in each individual basemap. Last I checked, you D/L the software and, as an option, D/L all the basemaps. You have to open each one and look at the settings.

 

I figured that. Since you have the software, can you see if the minimum opening time for an injector part number is available? If not, then they will need to be measured.

 

However, getting the exact minimum injector pulsewidth is largely irrelevant if you already have a tuned car in all but the most basic standalones (of which Megasquirt is not) or if you have a horribly large injector set. I have personally set up 1200 cc injectors on a 2L 4cyl without having the exact pulsewidth. It simply helps when crafting a rough map when first setting a car up.

 

We are talking about minimum opening time for a given injector design. This is determined by the electrical and mechanical characteristics of that particular injector part number. It is very important if you are setting the PWM up in MS with low Z injectors. Other ECUs may use high Z injectors or external resistors, and in that case it is irrelevant.

Link to comment
Share on other sites

We are talking about minimum opening time for a given injector design. This is determined by the electrical and mechanical characteristics of that particular injector part number. It is very important if you are setting the PWM up in MS with low Z injectors. Other ECUs may use high Z injectors or external resistors, and in that case it is irrelevant.

Yes, I know, but I would still humbly disagree. I have tuned many low-z cars as well without knowing the minimum pulsewidth. I don't have the software, anymore. I'll have to see if I can snag it again. It should be in stickies on the aempower forum, however.

Link to comment
Share on other sites

Yes, I know, but I would still humbly disagree. I have tuned many low-z cars as well without knowing the minimum pulsewidth. I don't have the software, anymore. I'll have to see if I can snag it again. It should be in stickies on the aempower forum, however.

 

I'm talking Megasquirt only here. It's not about knowing the minimum opening time, it's knowing what to set the PWM parameters to for the injectors you are using. The only way to do this is by determining the minimum opening time using the Megasquirt PWM parameters, a current probe, and a scope. Once I determine the minimum opening time I add some padding to the PWM parameters so that the injector drivers always deliver a little more current than is required to fully open the injector in the minimum time. But not too much current where the injectors or injector drivers overheat. The goal is to give the injector just enough current to open fully as quickly as possible. Giving the injector a little extra current is to account for variations in injector characteristics from on injector to another.

 

If you are going to use the PWM feature on Megasquirt you really need to know this. For other ECUs, you are right, you don't need to know this because these settings are hard coded into the ECU to work with "typical" low Z injector characteristics. For Megasquirt (without using series current limiting resistors and low Z injectors), you have to set the PWM correctly. If you just guess, either the injectors will never fully open, the injectors will overheat, or the Megasquirt injector drivers will go in an out of thermal overload. I know this because I can make it happen on the bench.

 

Aftermarket commercially available ECUs do not give you this level of control over the injector drive characteristics (most likely for warranty reasons). With this level of control comes flexibility, but also risk if you don't set it up correctly.

 

Pete

Link to comment
Share on other sites

  • 4 months later...

×
×
  • Create New...