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Old 12-23-2008, 01:33 AM   #1
N3v
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Default Stim boots ECU, car doesn't

I hate to post a thread about this, but I can't figure this out.

Let me start at the beginning. A couple of days after I took my MS apart to add tach function and cleanup my wiring job, my car started running like crap. It took a couple of tries to get it started and it would stumble and backfire out of the ITB runners. It would idle high, but after a minute the idle would try to go back down to the normal 1k but keep dropping and stumble and die. It would rev alright, but driving under load was near impossible, in the low revs it would pop and jerk.

So, cjernigan recommended flashing my MS after making changes to my wiring and that might fix it, but I decided to try swapping the plugs first, as they were kinda old. But nope, same problem. It revved a little smoother at idle, but same popping and jerking under load.

So, having eliminated that as a problem, I flashed the firmware (ms-extra). I used my stimulator to flash it, and all went well. I plugged it into my car to load my .msq but as soon as i turned the key to the 'ready position' (no msq loaded), my IAC started making a high pitched noise. I don't know what causes that, but I know it makes that noise when it doesn't like the signal its getting. So I quickly turned it off and hooked up the stim to load my msq, but when I hooked it up to my car again, the car won't boot the megasquirt. The IAC doesn't make any noise either. The stim will turn it on just fine, but not the car. The most likely culprit to me seems like a fuse, but all the ones under the hood look good.

So, could it be a different small/weird fuse? Did I blow my IAC?
thanks.
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Old 12-23-2008, 11:08 AM   #2
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Check to be sure that (1) it's getting 12 volt power on the car and (2) that there are no shorts from VREF to ground. These are the most common causes of what you describe.
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Old 12-23-2008, 09:12 PM   #3
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fixed it. it was a 15 amp fuse in the top right of my fuse box near the pedals. I lost my fuse box cover so I don't know what fuse it was, but I basically pulled each fuse out until I found a blown one and replaced it.

My car still pops a little in the low revs, but I'm also trying to run a 0.055" spark plug gap :P Its totally normal above 2k rpms though.
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