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Scantool shows different readings than DMM

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Old 06-23-2006, 05:20 PM
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Default Scantool shows different readings than DMM

Hello...
I am going to blow this car up. I still have a miss that is driving me crazy. I pulled the #2 injector pigtail while running and no difference... plug was NOT fouled nor burnt from lack of fuel. after checking things and replacing the plug that I dropped (oops) it changes the idle when pulled now (as do the other 5.) While having my Scantool on there (Actron CP9110) my voltage only shows 12.8 while my DMM shows 13.8... what is the deal with this? Could this be the problem with my weird miss?
Old 06-23-2006, 09:43 PM
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I am assuming the DMM is the Digital Multi Meter?

Before you blow the thing up, see if you have voltage at the pulg for the injector, I am curious to know if each injector has its own fuse. I do not know
Old 06-24-2006, 12:43 AM
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i have 12~13 Volts at the injectors...
Old 06-24-2006, 01:40 AM
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Maybe check the gap on the plugs ( .060" )and check the ignition coils resistance per directions in "Tech Info" and report back.

Ed
Old 06-24-2006, 06:17 AM
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Just for craps n' grins, have you tried reseating ALL the main connectors in the engine bay? There are 2 big ones (one I am pretty sure has the injector wires on it) right near the alternator (which btw if you have leaky valve cover gaskets these will be rather nasty looking), and then there is the main connector at the firewall (I would not suspect this but one never knows).
Old 06-24-2006, 06:26 AM
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Have you checked the resistance of the injector to make sure its good?
Old 06-24-2006, 11:29 PM
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Try noid light to see if injector pulse is steady?
Old 06-25-2006, 07:50 AM
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are you sure that its the injector??

there are a lot of things that can cuase a miss...

have you checked the coils?
have you done a compression test?
Old 06-25-2006, 08:07 PM
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Injectors are typically supplied 12v as long as they key is on and the computer fires them by grounding its other wire. The transistor for that wire inside the computer* could be fried or a problem in the wire.


* depends on the injection type, sequential injection typically fires them individually.
Old 06-26-2006, 08:15 AM
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I switched the computer with a known good and problem still persists. Any more suggestions? Could the BCS be bad? anyone know the symptoms for this piece?


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