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97 Z71 misfire #3

Old 02-20-2011, 08:09 PM
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So i have ordered some more parts, in hopes to eliminate the problem.. Ordered a Magnaflow Catalytic Converter complete system (manifolds to muffler), as well as a new Delphi MPFI conversion fuel injection "spider".. got my fingers crossed! let you know how it goes when they get on..
Old 02-21-2011, 01:32 AM
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yes let us know if you need anymore help
Old 02-21-2011, 12:05 PM
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What you could also do is check your valvetrain. Take the valve covers off and see maybe if you have a busted spring or rocker arm. This will also cause a misfire.
Old 02-23-2011, 03:59 PM
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OK so here is the update... Valve adjustment done - no change, coolant temp sensor, pcv, cleaned MAF - no change.. New delphi MPFI "spider" harness - DONE!! RUNS Perfect and NO LIGHTS!! it was easy to do, took about 1 1/2 hours of my time and *presto* back on the road! Didn't even have to remove distributor or water neck as some suggested.. i have pics of the process (if interested) and info on where to get these Delphi MPFI units pretty cheap compared to most places..

Now my decision is what to do with the new Magnaflow Cat system when it gets here. Should i put them on? Ship them back and get refund? or just hang on to them in case my OEM ones go bad?? Got a Heck of deal on them too, so i may hang on to them..

thanks everyone for the help!
Old 12-02-2011, 10:16 PM
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Default Fix for the p0303 code

A leaking intake mainfold gasket will cause a p0303 or p0305. To check this get carb cleaner and spray it on the gasket and if it smooths out then that is the problem
Old 12-05-2011, 04:18 PM
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I had the same thing happen to mine. Wish I would have seen this post earlier. Yeah, just do the starter fluid thing around the intake to see if the RPM's increase. Or, you can tell your vacuum leak by taking off the Engine Oil Fill cap, if you can tell an RPM change, or your truck dies, or you can put your hand over the oil fill and you have suction = intake vacuum leak. $100 part could've saved you some cash on all those other parts.
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