96 Lumina P0300 code

Hello,
I have a 96 Lumina 3.1 and the engine light is starting to come on. It will start blinking for a few seconds and then stay on. It will go off in a couple of days but then will come back on. The car runs and idles great and it seems to only do this at highway speeds. The code is P0300. The car has 250,000 miles with new spark plugs and wires (AC Delco). Any help would be greatly appreciated.
Thanks

Many things can cause this, low fuel pressure, dirty injectors weak spark, are just some, a full scan looking at misfire counts is step one and check fuel pressure also.

When was the last time you ran injector/fuel system cleaner through the system?

Has the timing chain ever been changed?

Thanks for the replies. I have been running injector/fuel system cleaner for the past month to see if it would help but the timming chain has never been replaced. I have good fuel pressure at the rail and good spark at all the pulgs. The light went out on the way to work but came back on about 5 min later.

Thanks!!

blinking is warning of possible emission damage if engine continues to operate with the light blinking. Cylinder might not be firing, clogged cat, vacuum leak, sure there are many reasons to cause it to go off.

you code says random misfiring. probably not cylinder head leak or a bad wire, check cat, throttle body, air filter, ignition and wiring harness, etc....

i got the random misfire when my LIM coolant leak eventually killled my cat...


to avoid it blinking and misfiring ... accellerate slowly and dont go fast

theres also a known issue with one of the wires heading to either the crank or cam sensors becoming pinched/streched. 3.1s also have a issue with some of the injectors that have been installed over the years.
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Check for timing chain slack, if more than 3/8" replace it with new timing set including gears. If chain breaks, there is a lot of internal damage to engine that will result as this is an interference engine.

Check for timing chain slack, if more than 3/8" replace it with new timing set including gears. If chain breaks, there is a lot of internal damage to engine that will result as this is an interference engine.

very valid point there, but, i havenot seen many p0300 codes set from a worn timing set. im not saying its not inpossiable, but i have not seen it yet. is it possiable, yes.

ihave a 96 lumina with the 3100 also. burned out check engine light. when i first got the car it ran great, but then noticed the c.e.l. was burned out. checked the codes to find p0300. pulled some magic tricks outta my mechanic pocket (14 years in the automotive repair business) and never poped on again. 179k on the clock, 3rd owner, and a glove boox full of repair invoices. no timing chain replacement ever. the car lived most of its life in chicago and now lives in rockford.

if it were me, id look for other culprits. maybe a bad fuel filter/fuel pressure, bad ingition control module, or somthing else before the timing chain.

just my opinion. not tryin to step on any toes or post nothing but sarcasm. hope ya find the fix.

I'd agree. The timing chain would be one of the last things to check. Not because it isn't valid, but because it isn't easy. There are too many other easy things to check and eliminate before tearing off the front cover of the engine.

The coil packs, wires, plugs, ICM, EGR (consistent with a problem at highway speeds), injectors, fuel pressure, O² sensor, all the wirign to all those devices, and many other things can set a 300.