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Old 05-26-2010, 07:54 PM   #1
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Default 20+psi at zero RPM!

That's how I start my car bitches!

Turn the key to prime the fuel pump: MS turns on, fires the coils, and in turn the plugs spark, and I get a large 'poooooooffffff' sound with the accompanying pegging of the boost gauge.

The car is difficult to start after this happens, and takes around five seconds of cranking followed by a stumble that takes close to a half minute to clear.

This does not happen on every start. Most frequently it seems to happen when I start my car to leave work, after maybe 10 hours or so. Does not seem to do it as often, if at all, in the morning after sitting all night, and starts crisply.

This would be a MS1 running TunerStudio on a 1994.

How do you suggest that I eliminate this problem? I can not imagine that it is healthy for the engine...

Videos tomorrow as long as I get both conditions.
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Old 05-26-2010, 07:57 PM   #2
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Look up JoeP's 'better ignition circuit'.

Basically what is happening is residual fuel (most likely from leaking injectors) is pooling in your cylinders. When the key hits the 'ON' position, the coils fire and you get a backfire through the intake manifold. Since your throttle plate is most likely closed, the huge pressure spike you are seeing is actually the result of combustion pressure.

Joe's mod changes the way the ECU drives the ignitor. An added benefit to joe's design is that you don't need to unplug your ignitor when you flash new firmware .
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Old 05-26-2010, 08:03 PM   #3
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Similar issue:
POP when turning ignition on (not cranking) and burned fuel smell

Better spark out circuit:
A better Spark Out circuit.
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Old 05-26-2010, 08:21 PM   #4
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Looks like I missed some pretty influential threads... I have some reading ahead of me.

Thanks for the quick replies.
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