beagling

CEL light came on solid on my 2002 Turbo. I connected my ODBII scan tool and it showed that I was throwing a P0300 code. The light was on for a week or so. Gas was below 1/4 tank. When I filled the tank the CEL was gone immedately after starting and hasn't retuned in 3 weeks now.

I'm guessing the gas cap was not on correctly/tightly?

Posting this in case others experience same issue.

dprantl

P0300 is random ignition misfire. You may have had some bad gas? Or maybe it is time to replace the coils and plugs. However, with the latter there is usually another code indicating exactly which cylinder(s) misfired.

Dan

993GT

+1 on bad fuel, if no P030X code the most likely fuel related

Macster

The gas cap or fuel level had nothing to do with the misfire codes.

It is possible you didn't read all codes. P0300 is based on my experience always accompanied by the cylinder specific misfire codes.

Based on my experience it would have to be some pretty bad gas to cause the misfires.

More likely you washed the car or it was rainy where you are or it just got damp/humid and the misfires were from this.

If the car was dry the weather dry then my WAG is the coils are going bad.

When were the plugs last changed?

Fuel filter?

Engine air filter?

993GT

'Long-term', a P0300 without any cylinder specified P codes is almost never a spark issue for C.O.P. cars.
Fuel level if low enough and driven hard could definitely be starvation

Kevin

Rob nailed it... Fuel starvation due to the Venturi lift pumps struggling at low fuel level tripped the CEL..

I question the health of the nylon and rubber fuel line attached to the fuel pump/swirl pot..

Public Service announcement>>> If you have never replaced your fuel pump>>do so.. OR at a minimum, inspect the nylon and rubber lines..

Second statement.. When you get near the reserve fuel light, STOP boosting your engine. Stay out of WIDE OPEN throttle or aggressive driving.. FILL the tank with fuel! Misfires and fuel starvation will get you past "go" and instead of collection your $200, you will end up paying for a new engine rebuild..

"02996ttx50

sounds like a code that has to say something doesn't quite know what, hence 0300

Macster

I was wrong. Fuel level, low low fuel level, could trigger misfires.

From the factory manual:

When the fuel tank is driven to empty, misfiring can occur. For this reason the fuel level in the tank is also stored in the memory when misfiring occurs. If the tank was nearly empty, there was probably no fault. Erase fault memory and road test vehicle.


Also, apparently there can be P0300 without other specific cylinder misfires.

Possible fault cause:

♦ Fault in ignition system
♦ Fault in injection system
♦ Flat-base tappets (valve lift fault)
♦ Mixture too rich
♦ Mixture too lean

The OP will have to do a bit of investigation.