Mechanics

CHEVY 4X4 MULTIPLE MISFIRES

1998 Chevrolet Truck

Mulitple misfires- replaced plugs, wires, cap, rotor, injectors, timing

Under light load miss with mulitple cylinder misfires

check engine light does not come on, with scanner hooked up, shows 2 or 3 cylinders misfiring

fuel pressure check- ok, injector balance check-ok, EGR - ok

Any Ideas?
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Ant aftermarket electronics installed recently? Alarm? Or ever an oiled air filter system? If not Check your coil(s)

Merlin2021
Apr 7, 2008.
If you can, find a scan tool and see what the fuel trim is reading when the misfire is happening. Sounds like you may have a upper intake leaking vacuum, or a possible O2 sensor shorting out.

Tiny
Rhall77
Apr 7, 2008.
Yes, I know for sure that the Radio & Boom Box are after market. I will check this morning for anything else that might be. Thanks again, upfront, for any ideas. I'm banging my head against the wall with this one!

Yes, I know for sure that the Radio & Boom Box are after market. The alarm system is, as well. I will check this morning for anything else that might be. Thanks again, upfront, for any ideas. I'm banging my head against the wall with this one![/Quote: e1e2488890]