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Megasquirt starts, then dies...

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Old Aug 31, 2012 | 01:47 PM
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starts, then dies...

So I'm attaching a copy of my log... the car starts fine, smoothly revs to about 3K, then dies.

The strange thing is that it actually idles (albeit poorly) without the MAP sensor connected, which leads me to believe it is related to that.

I've never gotten a reply in this section yet... but this time I really need help. Thanks in advance!
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2012-08-31_14.19.45.zip (4.9 KB, 26 views)
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Old Aug 31, 2012 | 02:42 PM
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Make sure your fuel pump is staying on when the car starts. Could be that!
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Old Aug 31, 2012 | 02:45 PM
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If stays on when the map vacuum line is unplugged... so I doubt it, but thanks... and keep tossing out ideas!
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Old Aug 31, 2012 | 04:37 PM
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Oh I get it now, didn't read that properly. You have a MSQ of your setup that you can post?
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Old Aug 31, 2012 | 05:28 PM
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Old Sep 1, 2012 | 10:12 PM
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anybody?
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Old Sep 2, 2012 | 10:22 AM
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I can't open your tune (unzips to a file "current tune" with no extension, TunerStudio opens it and nothing happens) but I'd guess based on your description that the VE table is too lean. Assuming all other settings are correct.
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Old Sep 2, 2012 | 11:07 AM
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Heh... so heres an update.

I got pissed off with the settings I was given (for free, so I cant be too mad ) So I went back to square 1 with Aaron's settings/tables. Fired and idled on the first crank. Should have done that in the first place. Even with the MAP vacuum tube plugged in... and the BAC plugged in.

But for some reason my dash tach is reading 1000 rpms above what the MS is seeing... and I know that the MS is right.

Gotta say thanks to DIY Autotune for distributing an excellent product, and everyone else involved in making something like this happen. Aaron, thanks for the writeup. I didn't use the whole thing, but you are the one that ended up getting me through it.
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Old Sep 2, 2012 | 08:14 PM
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Hi, from were you are getting your RPM ?
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Old Sep 3, 2012 | 01:56 PM
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the leading coil i suppose?
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Old Sep 4, 2012 | 06:11 AM
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I have mine direct from the coil ( - ) connector leading also, for me is working.

Do you always see 1k above or is always double compared to MS ?
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Old Sep 16, 2012 | 10:17 AM
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The tach pulse should come from the trailing coil. Yellow/blue wire.

If the tach is reading twice the actual RPM of the engine, the coil is firing twice as often. Reversed coil connections?
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Old Sep 19, 2012 | 05:38 AM
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Originally Posted by Aaron Cake
The tach pulse should come from the trailing coil. Yellow/blue wire.

If the tach is reading twice the actual RPM of the engine, the coil is firing twice as often. Reversed coil connections?
Ehh, sorry. I should have updated this thread. Yes... its the yellow/blue wire at the trailing coil.

That wire is obviously unmolested when installing the MS.

I think this might be a bad ground. There isn't any linearity to the curve... it idles at more or less the correct position, but when cruising at around 2000 rpm, the tach is reading over/at 6000 rpm. I think I'm going to add a ground at the back of the cluster and see if that helps.
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Old Sep 19, 2012 | 08:18 PM
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Sorry, my car is a FB, so it may be different from FC.
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Old Sep 25, 2012 | 10:22 PM
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So here's an update, I ran another ground from the tach harness to ground, but no solution... then a few seconds ago I thought about it a little more.

The tach is generally double the actual RPMs... and the trailing triggers are both somewhat near the tach input blue/yellow wire... maybe its picking up both of those triggers as noise - wouldn't that cause a double (sometimes triple) RPM reading?

Tomorrow I'll shield both of those wires with foil/shrink wrap and see what happens.
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Old Sep 28, 2012 | 04:52 PM
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So no... this is not a shielding issue. Guess I need to check and make sure that my coils aren't firing at some retarded rate. Hopefully my tach is just **** up.
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Old Sep 29, 2012 | 10:39 AM
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Can you check timing on both leading and trailing with a timing light and confirm everything is OK?
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Old Sep 29, 2012 | 02:12 PM
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it runs... very well actually - except for the untunedness...

I'll throw my timing light on to make sure that it is firing, but it doesn't do RPM.
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Old Sep 29, 2012 | 02:13 PM
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any chance this may be from the ignition settings? should one be on cam and one on crank? or both on one?
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Old Sep 30, 2012 | 10:17 AM
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OK...What MS version?
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Old Sep 30, 2012 | 10:33 AM
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MS2 v3.0 board... using tunerstudioMS 2.0.5 and firmware is 3.1.0

Another question is on WUE, that light is always green... even after it passes the last point on the graph, it stays in WUE mode. Havent seen a setting for the WUE range... weird.
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Old Oct 1, 2012 | 09:27 AM
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WUE stays enabled until it's at 100%. If you never have it at 100% the light will never turn off.

Ken
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Old Oct 1, 2012 | 11:17 AM
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Originally Posted by muythaibxr
WUE stays enabled until it's at 100%. If you never have it at 100% the light will never turn off.

Ken
Awesome. I thought that was a possibility!

So the only real issue is the in dash tach speeds... I'm really just worried about burning out the coil if its being overworked.
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Old Oct 1, 2012 | 11:39 AM
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Try unplugging the secondary coil and lock timing and check the leading plugs with a timing light. I don't see how you could have switched the leading and trailing wires and it still run ok. If you can get a hold of a scope and current clamp you can check all your plug wires and make sure they are correct (pri is wasted spark, sec is coil select). If that is correct you could try connecting the tach from the sec. coil and use the megasquirt tach output. If megasquit is reading engine speed correctly that would allow you to see if anything is wonky with your gauge cluster.
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Old Oct 1, 2012 | 11:44 AM
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thats what I was thinking too... the car actually runs fairly perfectly except for the tune. I drove it 60 miles to a show and back this weekend and really enjoyed it.

I really dont think its a wiring issue... it just runs too well, and the tunerstudioMS RPM readings are dead on.

The plug wires are brand new NGKs and even with the old NGKs it was doing the same thing. It has to be something in the ignition settings.
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