'96 5.7 Vortec Miss..

[corning_d3]

I'm working on a '96 1500 P/U w/ a 5.7 Vortec SFI, according to the VIN. It's got a nasty miss at idle on #5 cyl. I've got hot spark, 190psi of compression, but no fuel smell on the plug. I'm assuming this has the central injector with the poppets, am I correct? I'd like to know before I start pulling the plenum and ordering parts.

EDIT: Or maybe it has injectors.....n/m

[wafrederick]

Pull the distribitor and inspect the distribitor gear and it will cause a miss.It might be a worn out distribtor gear and look for shiney spots.GM does have problems with the distribitor gear.Mark the distribtor before pulling out,the timing is not adjustable and has to the distribitor has to be set with a scan tool(+ or - 0 degrees).I have seen this happen,it was missing with no check engine light on and tried plugs,still missed.Finally pullled the distribitor gear out and found the distribitor gear was worn out.The miss was gone after replacing the distribitor gear and setting the distribitor with a scan tool.

[corning_d3]

Another mechanic friend recommended that, also. The gear looked fine, considering the engine only had 65,000 miles on it mostly idling. I think it was a phone company truck. So I pulled the plenum cover and the injector ass'y and soaked the poppet nozzels in carb cleaner for 30 min. Fired it up, but it still missed and smoked like hell for a few minutes. Then it cleared up and started running good.. Finally figured out how it got clogged up after pulling off the fuel filter...It had a small hole in it, and the tank only had almost a gallon of nasty fuel in it..