USAFPILOT

Well for the second time in 3 weeks I have this code.

DTC P0300 Random/Multiple Cylinder misfire detected. The car is running perfect.

Any ideas? Should I give it some new plugs? Could I have got some bad gas? Is it BS?

Thanks

TM-Z06

Double check the spark plug wires - one of them may be touching the exhaust manifold.

USAFPILOT

If that happend wouldn't it burn through, then continue to misfire?

96GS#007

Do this test....at slow speed (20mph or so), shift into 5th gear and go WOT. Obviously the car won't go anywhere fast but the engine should lug along smoothly. If you feel definitive bucking/missing then you have one or more of the following issues...plug wires, spark plugs, coil, optispark.

If the wires are original and you have significant miles on the car...>40k, they're no doubt ready for replacement. Ditto for the OEM plugs which tended to lose their platinum pucks.

runner140*

Either in the dark or in your garage with the lights off, start the car with the hood up and see if you have any arcing of your wires on either side. If not, check your plugs. They could be fouled or missing a puck.
Always go with the cheapest and easy fixes first.

TM-Z06

Maybe - maybe not. I had a wire that touched the exhaust manifold to a point of having a burn pattern on it. That caused a mis-fire and set of the check engine light.

Landry337

I just changed my plugs and wires and car ran fine. Have ACDelco Platinum, like stock, and 8.5mm wires. Ran fine for about a week, now when I push on the throttle and give it some, even slightly, it bogs down. The code isn't on yet. Hope its not the Distributor, even though I plan on getting an MSD soon.

tlong

I have a '96 too. The PO300 code is a beotch because it isn't specific to a cause. It says 'random' but it's usually one cylinder. The '96 doesn't specify like later LS1. Could be ignition or fuel delivery. If you have a good shop let them hook it up and get the misfire counts on a specific cylinder. If not try the dark place arching routine or pull each injector harness then each plug wire. If intermittent then the fun begins as nothing will be diagnosed unless it's missing.

My nightmare was human error. The idiots crossed the injector harnesses and you can't believe how difficult it was to find. It actually ran pretty good out of sequence but fired that code and SES. Brutal.

You probably have bad wires or plugs. One or more injectors could be acting up. Good luck and report results for further assistance. After new FIC injectors, Opti, wires, plugs and head work I have to say it runs strong, a far cry from the sick puppy PO300 hell on earth.

Good luck with your problem.

Landry337

Just found the issue. Thanks. Plug wire burned on header. Oops!

MK 82

FSM 6-448 to 6-452. Good reading.

crmvette

i have the same problem code will set during any type of driving. after a little research found may be a vibration/bump concern.compuyor will read this as a mis-fire.

good luck

ps. mine due to single mass flywheel