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Old 09-26-2010, 12:32 PM   #1
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Default Intermittent no power below 3000rpm

Having some problems with how the Miata is running and looking for thoughts on where to look for the problem...

Quick background on the car:
97 Miata
WRX turbo
550 injectors
MSPNP

This problem is intermittent, it comes and goes with no apparent pattern or trigger. Sometimes the car runs fine all day and other times, all of a sudden it loses most of its power. When the car is running well, the engine revs freely when you press the gas. Pulling away from a stop there is good power. When the car is running poorly, the engine is sluggish to rev below about 3000rpm when you press the gas. Pulling away from a stop, there is no power. The car can barely accelerate itself and it will be making 5psi or so of boost to do this.

When things are good, at idle:
Idle vac: 20inhg
Engine RPM: 1050rpm
Wideband reading: 13:1

When not running well at idle:
Idle vac: 8-10inhg
Engine RPM: 850rpm
Wideband reading: 10.5:1

Any thoughts on where to look for a problem or things to test??

thanks
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Old 09-28-2010, 10:56 AM   #2
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Check for leaks.
The change in idle vac suggests for this. Perhaps a connector or hose comes loose or wiggles itself out under the right condition. Check your hoses and clamps.
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Old 09-28-2010, 11:35 AM   #3
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datalogs.
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Old 10-03-2010, 01:47 AM   #4
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Quote:
Originally Posted by bogly View Post
Check for leaks.
The change in idle vac suggests for this. Perhaps a connector or hose comes loose or wiggles itself out under the right condition. Check your hoses and clamps.
I don't think that it is a vac leak because when the car is running poorly, the idle drops when the vac drops. If I disconnect a vacuum line to introduce a vac leak, it causes the vac to drop like above but the idle increases.

I took a data log the other day, will upload it tomorrow.
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Old 10-03-2010, 10:38 AM   #5
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Quote:
Originally Posted by Braineack View Post
datalogs.
and perhaps a faulty injector
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