Mechanics

99 P0300 RANDOM/MULTIPLE CYLINDER MISFIRE DETECTED

Pontiac Grand Am

Hi I am having an issue with my 99 Grand Am. It has a 3.4L V6 3400 engine, with approx. 87k Miles. Here is information on what we've diagnosed so far

Engine Code:
P0300 Random/Multiple Cylinder Misfire Detected

- Changed the Spark Plugs, Wires, and Coil Pack with no result

- The car skips and backfires, and won't go much above 2000 RPM's then sounds like it's sucking down air.

- Won't go down the road above 10-15 MPH, and starts sputtering and skipping, esp uphill.

other known issues involved with the above code are:

EGR Valve
Catalytic Converter
Fuel Injectors
Exhaust Valves

If you know what may be causing my problem, have more questions, or have an answer, please respond, or email me @ schicherchia@aol. Com. You can also reach me on aim if I am not away, my sn is schicherchia. Thanks
Avatar
Schicherchia
October 13, 2007.



Hello !

Well start Checking the ignition module.

Its " random misfire" right: P0300 Random/Multiple Cylinder Misfire Detected

which means that its not an especific cylinder.

Also check the plastic casing that holds the leads to transsmit the spark, from the coils to the plugs.
Check it, even if visually looks good ! The " spark" could be not insulated and " jump" with no control (causing missfire)

We like to know if our help has been useful !

Tiny
Fisherman
Oct 14, 2007.
If you mean the casing under the coils we pulled a fresh coil pack from a 2002 grand am @ a self pull junk yard, the base and the 3 coils, so if that's what your refering to it's a no go. However we'll look into the ignition module. Also we're gonna do testing to see if it's the Catalytic converter. I'll get back tomorrow evening if I get any results

Tiny
Schicherchia
Oct 14, 2007.