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

I have about 10000 miles on this MS-I in my supercharged yugo daily driver and countless miles on it in a previous car. The other day, it didn't run very well and then it kept flooding. Now the injectors get grounded as soon as it is powered up. the board (version 2.2) smells a little burnt. Overall it looks ok, but U7 (34151/IXDI404PI) FET driver seems like it has a little crack with oily discharge over one of it's 8 pins. I was getting some rpm spikes during cranking, but it would start anyway so I left it that way. Had the coil too close to the harness. Moved it now and shielded the tach wire better. Have a nice cranking tach signal now but it dosn't help because the board is powering the injectors as soon as the board is powered up. Sorry I don't have the ini version # handy. please remind me how to find that, if I need it. What could be causing this , and what can I do about it?
I really need this car to get around and I really appreciate the help!
Thanks!

Joffrey wrote:the board (version 2.2) smells a little burnt. Overall it looks ok, but U7 (34151/IXDI404PI) FET driver seems like it has a little crack with oily discharge over one of it's 8 pins.

There's your problem. Replacing U7 is likely to fix it.

BTW, I'm aware of at least two other MegaSquirted Yugos out there and personally worked on one of them.

Thanks Matt! Like your book "Performance fuel injection systems" by the way. I didn't really think I needed it, having run megasquirt for many years but just a single point like "keep the ignition wiring away from the sensor wiring" made it well worth the money!

You're welcome. I'm glad you liked the book!

So I have that new U7 installed, Thanks for the speedy shipment ,DIY! Sure enough no more flooding, Still won't run though. It fires right away and dies just as fast then cranks without any additional fireing. Iv'e experimented with adjusting the fuel, both cranking and required fuel - it seems to like more but still just fires to go from "cranking" to "warmup" and dies. Even on starting ether, when you think it should run a bit longer on it. It shouldn't require changes to the fuel as it was running before. No changes were made to the timing either. I did ground the shield for the rpm wire that goes to the coil. The rpm while cranking looks correct now. Maybe acting as a capacitor and weakening the spark when it trys to run?
could the injectors be damaged from being held open so long before?
could the U7 be in backwards? it didn't have the indent on the one end to show which way it gos. All the other chips that have that indent, have it to the left as you read the chip right side up. I assumed that the missing indent should be to to the left as you read this one as well.

I've gone back to the manual instructions on how to set cranking pulse width and warm-up enrichment. still no luck. Tried ungrounding the rpm wire shield to no avail. The way my ignition is set up I have to turn the key off each time I crank the engine, I tried using a wire to my starter so I could crank it multiple times without resetting megasquirt. It only fires the first time it is reset. I cut the priming pulse to 0 so I would know it's not firing up on that. Datalog shows cranking @ 300 rpm with 5ms pulswidth, catching right off and climbing to 1200 rpm and then right back down. Pulse width gos to about 18 as it exceeds cranking rpm and reduces as engine vac is created. I've tried all sorts of variation on warm up enrichment and after start but it seems to make no difference.
COULD IT BE THAT MEGASQUIRT IS NOT PUTTING OUT A GROUND TO THE INJECTORS ONCE IT STARTS?? My stimulator is home ,about 200 miles away. I've tried hooking an 12v led tail light to the injector output no blinking not even at first after a reset. Hooked a beeping circuit tester to the injector out put and ground, figureing it should beep when the MS grounds them but I didnt hear anything. I would think then the MS is not firing the injectors at all but then how does it fire up at first? Is there a good makeshift way to test the output?

The MS would have to be firing the injectors somehow unless you're using a shot of starting fluid. Sometimes a wrong setting can command it to stop firing the injectors, though - if you could post a copy of your MSQ and a data log of an attempted start, that would shed more light on the situation.

We would use an oscilloscope in this situation, but they aren't easy to find. Theoretically, a LED across the two terminals of the injector should pulse when the injector fires, if the LED is in the correct orientation.

It fires up reliably without starting ether. I wanted to post a older datalog of it running but the one I have handy is too big. Can try sending it to your DIY email.

Doesn't look like the ECU is intentionally shutting down the injectors. This will be hard to diagnose without a Stim or oscilloscope.

I believe I have stim on order, sir. How are the roads down there? There was a note on your site about shipments hopefully going out Wednsday.

Unfortunately, the truck that was coming in to pick up the mail yesterday got stuck on ice and couldn't make it in. Hopefully they'll ship out today.

Hooked it up to my new stim - No fuel injector pulses out to the stim. Still see the fuel led on the MS1 blinking. Should I start a new thread on a different forum as this is not a "tuning fuel and air" issue?

Joffrey wrote:Hooked it up to my new stim - No fuel injector pulses out to the stim. Still see the fuel led on the MS1 blinking. Should I start a new thread on a different forum as this is not a "tuning fuel and air" issue?

Yeah, I'd start one under Troubleshooting.