Cylinder 5 miss fire 99 chevy 5.7

Asked by Chev994x4 Feb 06, 2017 at 01:41 AM about the 1999 Chevrolet C/K 1500 LS Extended Cab 4WD

Question type: Maintenance & Repair

Have a 99 chevy 1500 5.7 started out with check
engine going on but then it would go off pretty
quick then it started flashing took it to auto zone
said number 5 cylinder is miss firing changed plugs
and wires like they said and nothing happened now
I have to give it gas to start and it's running really
ruff it makes a popping noise and smells really rich
and goes through gas like no other. Any
suggestions on what else it could be before I spend
a bunch of money replacing everything? Please
help

2 Answers

224,155

Check the compression in the cylinders comparing them to number 5 cylinder, check for vacuum leaks, snug up the intake manifold bolts, check for proper fuel pressure. Other things to eliminate are, Faulty spark plug 5, Clogged or faulty fuel injector 5, Faulty ignition coil 5, Fuel injector 5 harness is open or shorted, Fuel injector 5 circuit poor electrical connection, Ignition coil 5 harness is open or shorted, Ignition coil 5 circuit poor electrical connection.

3 people found this helpful.
380

I don’t know if you ever found the problem.”, but it’s your fuel pressure regular under the upper intake plenum. It leaks raw fuel straight to a port that drains into cylinder 5. Makes for rough idle and bad exhaust smell. Should cost you about $75 to fix if you do yourself for the regulator and upper plenum gasket kit. Not too difficult, just take careful notes on what bolts come out of where in the plenum.

5 people found this helpful.

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