I've got low impedance injectors, flyback board, MS-II running the latest code. I've been trying to tune in my injector characteristics and have noticed that changes to PWM current limit don't seem to affect the idle quality. Changes to the opening time definitely does, and I've tuned that to 1.5 ms. My pulse width at idle is very low, around 1.3 to 1.5. Any suggestions on the PWM current limit parameter? I've got it set now to 35, as that seemed like a "safe" value to leave it at.
Thanks,
Patrick
PWM Current Limit: Changing it seems to make no difference
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Read the manual to see if your question is answered there before posting. Many users will not reply if the answer is already available in the manual.
If your question is about troubleshooting, configuration, or tuning, you MUST include your processor type (MS-I or MS-II) and code version in your post. If your question is about PCB assembly or modifications, you must also include the main board version number (1.01, 2.2 or 3.0).
If you have questions about MS1/Extra or MS2/Extra code configuration or tuning, please post them at www.msextra.com Such questions posted here will be moved to: a temporary MSextra sub-forum, where they will be removed after 7 days
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PWM Current Limit: Changing it seems to make no difference
'81 Fiat Spider - Turbo charged, MSII, EDIS4
'04 SRT4 - Daily driver
'04 SRT4 - Daily driver
Re: PWM Current Limit: Changing it seems to make no differe
PWM of around 30% should be fine for most low impedance injectors. Setting that to a lower number may not make your injectors open. Setting it to higher will allow your injectors to draw more current, summarily making them hot/overheating/failing.
To adjust your idle, you may want to set a 1.0ms opening time and adjust your req fuel to make target AFR of around 13.20 at idle.
If your opening time is set at 1.5ms and your idle PW is around 1.5 ms then that suggest that your injectors have little to no time to close at idle. You'll have a helluvatime adjusting VE.
Are you squirting simultaneous, or alternating?
What type of injectors are these? Are these pintle type, or disc type?
To adjust your idle, you may want to set a 1.0ms opening time and adjust your req fuel to make target AFR of around 13.20 at idle.
If your opening time is set at 1.5ms and your idle PW is around 1.5 ms then that suggest that your injectors have little to no time to close at idle. You'll have a helluvatime adjusting VE.
Are you squirting simultaneous, or alternating?
What type of injectors are these? Are these pintle type, or disc type?
Thanks for the response. These are pintle type injectors and I currently have them setup as follows:
Injector open time: 1 ms
PWM current limit: 35%
PWM time threshold: 1.5 ms
I'm running 4 squirts alternating on a 4-cyl engine.
-Patrick-
Injector open time: 1 ms
PWM current limit: 35%
PWM time threshold: 1.5 ms
I'm running 4 squirts alternating on a 4-cyl engine.
-Patrick-
'81 Fiat Spider - Turbo charged, MSII, EDIS4
'04 SRT4 - Daily driver
'04 SRT4 - Daily driver
If they're truly peak/hold injectors, and your opening time is 1.0ms then you probably want to keep your PWM time threshold @ 1.0ms as well. This is the amount of time that MS allows whatever the injectors will draw before it's limited.
If you're having troubles with idle and your pulse width @ idle is 1.5ms might I suggest that you switch to 2 squirts/alternating? This will lengthen your pulse width at idle. Of course, you'll have to re-tune your VE.
If this is for your FIAT, and it's turbo-charge I'm guessing that you're larger injectors? (Like >40lb/hr)
If you have an adjustable FPR, low pressure at vacuum helps as well.
If you're having troubles with idle and your pulse width @ idle is 1.5ms might I suggest that you switch to 2 squirts/alternating? This will lengthen your pulse width at idle. Of course, you'll have to re-tune your VE.
If this is for your FIAT, and it's turbo-charge I'm guessing that you're larger injectors? (Like >40lb/hr)
If you have an adjustable FPR, low pressure at vacuum helps as well.