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Old 06-15-2008, 02:02 PM
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BNaylor BNaylor is offline
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Re: Bought an Alero...bought a p0303...need help.

To test the CAT converter just run an automotive vacuum gauge (0-30 in-hg) and run the rpms up to a range of 2K-3K rpms and see what vacuum does. Connect to the upper intake manifold. If the gauge decreases below 15 in-hg and towards zero there is excessive exhaust backpressure or a clogged CAT. The problem with misfires is it will cause the CAT to heat up and may damage it.

What brand ignition wires and spark plugs to include heat range are installed? Most misfires are secondary ignition related.



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'08 Pontiac Grand Prix GXP (Dark Slate Metallic) - LS4 5.3L V8
'02 Oldsmobile Alero GL2 - LA1 3400 V6
'99 Buick Regal LS - L36 Series II 3800 V6
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'97 Pontiac Grand Prix GTP - L67 Series II 3800 V6 Supercharged (Sold)
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