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Old 09-12-2007, 09:20 PM   #21
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Here's what you can do to check out your car's grounds:

A) At the back of the fuel rail, hanging off the hook near the CAS, are two wires connected to a bracket. Just under that connected to a different bracket are two more wires. All 4 wires are either black or black with a green stripe. These four wires are your ECU grounds. They MUST have a very good connection back to the block/head. That means the bolt/stud/nut they are threaded onto, and any terminal the wires themselves use, must be clean and contaminant free (no oil, oxidation, rust, etc.). Make sure you have a good clean metal to metal connection.
B) Then trace these back the next step towards the block/head. Make sure the connection of the bracket itself is clean metal to metal all the way to the block or head. Clean it up and make sure there's a good connection.
C) Now, to make sure the battery is securely grounded to the engine block. In an ideal world, the engine block would be directly grounded to the battery negative with a nice fat cable. That's not the case on the Miata. The battery is grounded to the chassis, and to the drivetrain brace. Pop your trunk, and make sure the connection from the battery negative to the chassis (right by the battery terminal) is nice and sound. Clean it up if needed. Then you'll notice that ground continues with a fat black/yellow wire, on down through the floor of the trunk. If you lift the car up and look at the right side (pass) of the brace that runs from the rear end to the tranny you'll see where this large black/yellow ground wire hits the drivetrain brace. That's the last connection I can think of to clean up. Other than that it's the drivetrain itself (brace, transmission, and engine) that are the ground. So instead of the battery being grounded directly to the block it's grounded to the rear of the drivetrain on a brace and has to 'go the distance'. Not too bad if 'the distance' is clean and clear of corrosion. Worst case scenario you could run an equal sized ground from that point on the brace on up to a large bolt somewhere on the engine block.

The goal here is to have a solid, clean, unobstructed ground from the battery to the block, and then solid, clean, unobstructed grounds from the block to the ECU. Normally you wouldn't have to mess with any of this with the MSPNP but I'm willing to bet that you find something along the way here that is likely the source of weak grounding. And if so it may make the car ultimately run better period as weak grounding to the block can cause weak spark and all kinds of issues.


Other possibilities--
-----------------------
The only other possibilities I can dream up are:

A) If you've got some sort of aftermarket equipment that's causing alot of noise and interfering with the low voltage (sensor) signals. The most likely culprit would be an ignition box of some sort, but some fans have even been known to cause problems.
B) Another thought is a bad/dead/dying alternator can introduce noise into the system.
C) Last possibility I can come up with is it could have something to do with your USB adapter, an incompatible adapter or driver possibly. There are some out there that don't work very well with MegaTune, and some that don't, and yes they can cause resets, and communications problems including scrambled tables and such. I recommend the USB-2920 that we offer as it seems to be problem free. Note that if you're having problems (resets, tach dropouts, etc) when the USB adapter is not connected you can rule this out. A tach dropout you could see, a reset you can't really see unless you're logging though, which you need a serial connection for. You could use a direct serial connection if possible to test this, or try a different model USB adapter, preferably the USB-2920. NOTE-- item C here, the USB adapter, could only be a factor if the problem is ONLY occurring when the USB adapter is plugged into the MS.
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Old 09-12-2007, 09:21 PM   #22
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I also forgot to unplug my coils when flashing the MS to the extra code. Heard thats supposed to fry things up a little.

Originally thought my ignitor went on me but I have no problems running spark on the stock ecu.

Also just got my 460cc's in so Im nice and motivated to get this thing fixed now
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Old 09-12-2007, 09:21 PM   #23
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That is, of course, assuming your ignition settings are correct, including dwell, and that your ignitor isn't giving up the ghost. But unless you've overheated it at some point in the past I wouldn't suspect the ignitor.
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Old 09-12-2007, 09:22 PM   #24
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Heh... we posted that at the same time, and it does at least bring the ignitor into question. But it's not a definite-- I think you probably have a list of things to consider now .
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Old 09-12-2007, 09:28 PM   #25
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I'm gonna run a nice fat wire right to the block then just to make absolutely sure the grounds are good.

When I soldered the ground wires on the DB37 they asked for it to be connected to 3 pins. So I laid it across three pins and layed on a lot of solder. Thinkin about it now the wire itself doesnt make very much contact to the pins. It IS completely covered in solder at least. But does solder conduct well enought?

Ever heard of reflashing the MS-Extra code to fix a problem?
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Old 09-12-2007, 09:41 PM   #26
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You should redo those grounds on the DB37. Remove the mess you have on there now. If it was me I would solder 6 wires from 13-19. I think 14 is for a couple of the sensors. Just one ground wire attached to 3 pins is not enough you will overload that wire and it could cause serious problems.
So i vote, clean up the mess, and solder 6 individual 18 gauge wires to pins 13-19 and attach them to the wires you've mounted on the block already. Make them all connect to the same place.
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Old 09-12-2007, 09:42 PM   #27
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Quote:
Originally Posted by dedoky View Post
I'm gonna run a nice fat wire right to the block then just to make absolutely sure the grounds are good.

When I soldered the ground wires on the DB37 they asked for it to be connected to 3 pins. So I laid it across three pins and layed on a lot of solder. Thinkin about it now the wire itself doesnt make very much contact to the pins. It IS completely covered in solder at least. But does solder conduct well enought?

Ever heard of reflashing the MS-Extra code to fix a problem?
I thought you said there were 8 grounds from the block to the MS? If they don't go to the MS where do they go?

Reflashing code can fix a corrupt firmware/map problem, feel free to try it, but I'm not optimistic.
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Old 09-12-2007, 09:45 PM   #28
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I have a feeling he has that one wire connected to 8 somehow.
I think i read in the megamanual last week that the way MS works it doesn't draw much power but it does sink alot of power into the grounds and that is why they are so important. Pretty sure I read that pin 14 is specifically for the CLT, IAT and some other sensor, though i could be mistaken.
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Old 09-12-2007, 09:47 PM   #29
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Quote:
Originally Posted by cjernigan View Post
I have a feeling he has that one wire connected to 8 somehow.
If so that won't do you much good. They need to be individually run back to their own pins on the DB37 for maximum benefit. It wouldn't hurt so bad if the pins were tied together at the DB37 probably, though ideally they wouldn't be. Definitely not ideal to have them joining into fewer wires that then come into the DB37.
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Old 09-12-2007, 10:25 PM   #30
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Sorry I mean the 8ga wire is from the battery directly to the block. And I actually have 8 individual wires from the MS to the block. I took 1 small piece of wire completely stripped and laid across all ground pins and soldered quite generously. Then laid wires across it and soldered them.

It was never inteded to be that way but I messed it up when I did the first two and accidently filled in the almost all ground pins with solder.
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Old 09-12-2007, 10:41 PM   #31
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Then it's more than likely something else as mentioned above-- noise or ignitor...
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Old 09-12-2007, 10:46 PM   #32
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it's the ignitor.

anyone wanna take bets?
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Old 09-12-2007, 10:52 PM   #33
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I had first thought the ignitor was the problem as well but when I switched back to stock ignition and the misfire went away I started looking elsewhere.
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Old 09-13-2007, 10:58 AM   #34
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How much dwell are you running?

DIYAutoTune spark mods or Kags mods?
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Old 09-13-2007, 09:26 PM   #35
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DIY mods, non inverted. Currently at 5ms running now, .5 discharge time. I found I got lots of tiny misfires when I went as low as 3.5, anything higher and it went away. Too bad the big misfire didnt too.
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Old 09-13-2007, 10:49 PM   #36
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Thanks for the info, just confirming there wasn't a possiblity of something going on there, but that sounds right.

Hate to keep repeating myself, so instead I'll quote

Quote:
Originally Posted by FoundSoul View Post
Then it's more than likely something else as mentioned above-- noise or ignitor...
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Old 09-13-2007, 10:53 PM   #37
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Thanks a lot for all your help. I have a camping trip this weekend so I wont get a chance to check out too much more. When I get back I'll mess around with it and let you know if I figure it out.

Thanks again
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Old 09-13-2007, 11:15 PM   #38
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No problem-- FYI I'll be out of town all next week, gotta take a vacation sometime -- But Matt will be in the office, you can always shoot an email to [email protected] and he's quick to answer during the week. I'll see about having him drop by here as well.
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Old 09-25-2007, 09:44 PM   #39
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During my whole trip out I ran stock ignition and never had any problems at all. So that confirms its a MS related problem.

I have gone over all grounds and the battery terminals and everything is shiny clean. I've added an 8ga wire from the battery negative terminal straight to the bottom of the intake manifold. I also checked voltage at the battery with the car off, running and with various things on and off and everything looks good. 12v off, steady 14 on. Small spike of about 1 volt when I kick something on like the headlights that quickly settles back to 14. Then I tried disconnecting everything aftermarket which includes an alarm and stereo/amp.

After all this and I still have the misfire. My next step is to check over the MS board very thoroughly. I've already tripple checked all diodes, capacitors and anything with polarity. Now I'll make sure all resistors are good.

Does anyone know what components make up the ignition circuit?
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Old 09-25-2007, 09:53 PM   #40
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ECU-2-Ignitor-2-Coils

Kind of out of off the wall but did you clean your board after soldering it together to get the flux off? The megamanual recommends isopropyl alcohol, i would use atleast 90% or better. Sometime you have to scrap the flux off with a little wooden toothpick. I used alcohol and a toothbrush. Remove the MS chip when doing it and rinse with warm water once you have it all completed. Then let it dry completely.
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