94 jimmy 4x4 4.3 vortec running rough/backfire

[dblackmer]

I have a 94 jimmy 4.3 vortec. Changed plugs, wires, egr, oil and filters. adjusted timing to tdc. Still running rough and occassionally pops/backfires from under hood it sounds like. I am planning on changing the cap and rotor tommorrow. Any other ideas????

[MT-2500]

Originally Posted by dblackmer

I have a 94 jimmy 4.3 vortec. Changed plugs, wires, egr, oil and filters. adjusted timing to tdc. Still running rough and occassionally pops/backfires from under hood it sounds like. I am planning on changing the cap and rotor tommorrow. Any other ideas????

Did you use the bypass mode to set timing?

Make sure plug wires is not crossed.
Let us know how it goes.

[dblackmer]

what is the bypass mode?

[MT-2500]

Originally Posted by dblackmer

what is the bypass mode?

They have a bypass wire/connector on ign system that you have to unplug to put it in base time mode.
May be behind glove box or under heater core on inside engine compartment on firewall area.
Always put it in bypass/base time mode to set timing.

[dblackmer]

Thanks for the info. I changed the rotor, cap, feul press. reg and plenum gasket and then retimed using your advise and runs excellent now.

[MT-2500]

Originally Posted by dblackmer

Thanks for the info. I changed the rotor, cap, feul press. reg and plenum gasket and then retimed using your advise and runs excellent now.

You are welcome and thanks for posting back how it went.
Good Luck