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Old 07-02-2014, 05:05 PM   #1
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weird engine light problem

Alright so I got a 96 camaro z28, nothing crazy mostly stock. But the issue I'm having is that when the service engine light is ON it runs fine, never dies, stutters or anything. And when I turn the light OFF it dies randomly until the light comes back on. The code it brings up is the crankshaft position sensor A But I changed it twice, had a shop look at it and nothing....any help?
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Old 07-02-2014, 05:20 PM   #2
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Re: weird engine light problem

The crank sensor is only there for misfire detection. But it needs the data from the cam position sensor in the Opti to do the misfire calculations. Sometimes, a corrupt cam position signal will cause the CKP sensor codes.

The mystery is why it runs better with the CKP codes set... the factory manual does not indicate any actions when the code sets that would affect engine operation. I'm wondering if you have a problem with an erratic high resolution pulse signal from the Opti, and when the CKP codes set the PCM defaults to using only the low resolution pulse signal.

Just for the hell of it, check the short Opti harness for corroded or damaged connector pins, a broken clip that holds the connector on the Opti, or some missing insulation on the harness wires.
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94 Formula A3+1: 381ci all-forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams custom solid roller / TH400 + GearVendors OD / Strange 12-bolt - 4.11's / 300-shot N2O / Spohn suspension / 6-pt roll bar with integrated SFC's / AutoMeter instrumentation / MoTeC M48Pro engine management system / a few other odds 'n ends. 800HP/800LB-FT at the flywheel.
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Old 07-02-2014, 10:35 PM   #3
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Re: weird engine light problem

Well I just replaced that opti, put an msd opti in with wires and coil. So I don't know if it would be corroded but il look and see. Ya it's definitely weird how it runs good with the light on and not with it off
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Old 07-03-2014, 09:56 AM   #4
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Re: weird engine light problem

I have just sorted out two cases of people with surging problems, both of them with the MSD Opti. Problem is erratic high resolution pulse signals. One of them just had his MSD rebuilt for the second time, installed it, and had the problems from the first turn of the key. Second guy had his MSD for a couple years.

I personally would even think of buying an MSD..... the only thing you get for the extra $$$$ is extra problems.
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94 Formula A3+1: 381ci all-forged stroker - Callies Stealth, Oliver 5.85 billet rods, BME nitrous pistons / CNC LT4 heads / Comp Cams custom solid roller / TH400 + GearVendors OD / Strange 12-bolt - 4.11's / 300-shot N2O / Spohn suspension / 6-pt roll bar with integrated SFC's / AutoMeter instrumentation / MoTeC M48Pro engine management system / a few other odds 'n ends. 800HP/800LB-FT at the flywheel.
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Old 07-03-2014, 09:56 AM
 
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