MicroSquirt.com read only forum (Jan.15,2018)

(MS1, V2.2, MSnSE)

I'm running the MS on my 2.3T Ford with the low-imp injectors and built the unit with the flyback board with this in mind.

To get the car running I borrowed an .msq from someone and started there. One thing I didn't notice/pay attention to was their PWM settings, and later realized they had been using resistors instead of the FBB with their low-imp injectors. The PWM was set at 100% and 25.4 ms.
I realized a problem when one of the FI fuses blew when I was finally able to put the car under a bit of load (1-2 weeks of fiddling).

After digging into it and figuring out that I had the setting wrong, I worked on lowering the PWM to the "correct" values and went from there.

The thing is the idle has not been anywhere near as nice at 30% and 1ms as it was when things were set wrong. I messed with raising the PWM setting a bit (40-45% range) and the idle seems to clear up a bit. It's been about 3 weeks since I could really drive the car due to a broken clutch cable and weather issues, so I'm just getting back to this.

The car runs "ok" and starts fine (occasionally needs a restart, but that could be due to my cold-start settings), but it's not a clean as I think it could be. The idle was perfect before the fuse blew and I corrected the PWM settings.

Did I possibly damage something in the FB circuitry or even possibly the injectors (it was mentioned to me thaht it might happen)? The PWM setting is currently still 30% 1ms.

Thanks
Chuck

Chuck,

It's possible that either the flyback circuit never worked or the injectors were damaged. It's also possible that your set-up needs more than 30% for the PWM% too.

In general, a setting greater than 30% with the flyback board means that the flyback is not working properly. However, if you injectors are not all that low impedance (for example if the DC resistance is greater than 2.5 Ohms or so) then you might need more than 30% PWM%.

So at this point it's hard to say, since we don't know what the injectors would have run at in 'perfect' condition, and we don't know if the flyback wasn't working, the injectors are damaged, or the PWM% is too low for your injectors.

If this was mine, I'd:

- recheck the flyback board for obvious problems:
* Go over the manual again, and verify the each component and it's orientation, if applicable,
* Check all the soldered joints and connections,
* Verify that the board is getting a good ground,
* Verify that the board has 12 volts,
* Verify the signals at the X0, X1, INJ1, and INJ2 connections (with an LED tester and the MegaSquirt on a stim),
* Verify that there is 'infinite' resistance between the TIP125s and the heat sink,
* Verify that the connections are to the correct place on the boards (both flyback and MegaSquirt),
* Verify that you have V2.98+ embedded code (reload if necessary).

- measure the DC resistance of the injectors (and the inductance, if you have the equipment) to see how low the impedance is, as well as to check the variation in resistance between injectors (which might signal damage)

- measure the resistance from both injector terminals on each injector to the body of the injector. In all cases it should be infinite. If it is less than a MegaOhm or so, I would replace all the injectors, as they are likely fried.

- test the injectors at various PWM% to see what works best (also try experimenting with the PWM time threshold) as described in the manual.

If they are a 'medium' level of impedance, the flyback board checks out, and it runs better at less than 50% PWM, then I think I would run it that way. If they are 'very low' impedance (< ~1 Ohms), or they won't idle properly until 75% or more, I would replace or repair the flyback board.

Lance.

Lance-
I'll double-check the flyback board.

As far as I recollect, my V2.2 MS1 has the V3.0 code. ( I remember a V3.0 on the processor)

The spec'd resistance on the injectors is 2.35-2.4 Ohms.

When you say
" * Verify the signals at the X0, X1, INJ1, and INJ2 connections (with an LED tester and the MegaSquirt on a stim), "...I'm just looking for a flashing light correct?

Thanks
Chuck