Last night the engine started missing at idle. Runs fine at speed. Put the scanner on it this morning and get No.6 cylinder misfire. Shows it has misfired over 40000 times. I have anew set of plugs but haven't put them in yet. Will this be the fix or should I do the wires as well or even the coil? With only doing it at idle could this be a fuel delivery problem? I'm thinking spark as opposed to fuel since it goes away at speed. What has your past experience told you? 5.7 liter gas 99 suburban 250k miles.
Cylinder misfire
- Thread starter tugboat95
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zora
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if you mean code P0306 these are the possibilites for an OBDII system. Do a resistance test on the wires, 1k per foot of wire maximum. You didnt state the mileage on the current plugs. The second link gives you diagnostics for the ignition circuit.
http://www.obd-codes.com/p0306
http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/how-to-test-the-icm-1
http://www.obd-codes.com/p0306
http://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/how-to-test-the-icm-1
VanGo
New member
At 250k miles those are some pretty tired wires. I'd replace plugs and wires. Coil is probably okay if it's only one cylinder.
Nice website some good info there. Thanks
VanGo
New member
If the rest of the maintenance is as neglected, you might also consider new air and fuel filters. I'd change the coolant and transmssion fluids too, but that is me. When I bought my '93 'burb with 170K miles I went through it from front to back to get a baseline.
Already done all that as well as wires and rotor cap kit. Fuel filter is on the workbench along with with a new differential gasket and fluid. Also had the transmission fully serviced. Tech told me if they all looked that good he'd be out of business.