Mitsubishi Repair Problems? Ask a Mechanic for Answers ASAP
Hi,Whenever you have a P0300 without any other individual cylinder misfires, it is going to be something that affects the whole engine... meaning you don't have to worry about coil packs, wires, plugs etc as it is unlikely to have all four plugs go out at once, etc.We are more focused on MAF sensor reading, fuel pressure, fuel quality (old bad gas, contaminated/E85 gas) etc.Do you have a live data scan tool we can use to see what your fuel trims look like while driving?
Sounds good.I'd like to see your short and long term fuel trim numbers while driving to start with. MAF Hz or gm/s reading at idle and at 1500-2500 RPM would be good too.
Out of curiosity, has the vehicle run through more than one tank of fuel since this occurred? Or if only 1-2 tanks, did the initial fill up after running empty get run out too, or was it only partial fill ups after that?
The concern being perhaps you got a tank of bad gas (or mixed with E85 etc) and either have not run it out yet, or if you have been partial refilling it, perhaps it is still diluting.
Thanks... that is good, so odds are the fuel is not it if you have since put a whole tank of fresh in.The only correlation I could see otherwise with the running near empty being related to the misfire would be if the tank was run low enough that the pump overheated.... the fuel pump uses the fuel as a coolant which when run low enough causes the pump to run hot which could technically result in damage.If we can see those fuel trims that will help indicate any relation there without needing to get a fuel pressure tester etc.
Thanks. Just in gear and rolling is all that matters in that respect... the reason being if you are sitting still the fuel trims will sometimes stop dead at 0.That MAF reading is definitely suspect. Everything else looks OK.The MAF at 2000 rpm we would expect more like 1.7-2.5V.If you unplug the MAF, does the condition improve some (but not back to normal)?
Ah fantastic, that certainly gives us something to work with!
Possibly, but not necessarily. Please unplug injector number 2 and put a noid light or test light between the two pins of the connector. Crank the engine... does the light flash?If it does not, measure between battery negative and each pin of the connector with the key on... do you have power on one wire?
Thanks.... if you have constant power and you have flashing while cranking/running, then the circuit appears to be working normally. Certainly sufficiently that you shouldn't have an open circuit fault. There was no change whatsoever when you swapped the injector?
Just to avoid any confusion, you are working on the second injector away from the belt end of the engine right?
I just mean you are definitely on the second cylinder away from the belts is all.... sometimes people count these backward or count the firing order (1-3-4-2) across the top instead of 1-2-3-4 etc.If you are on the correct cylinder and you have 12V and ground pulse and the injector is known good, then you most certainly do not have an open circuit... which would mean there is a computer problem at hand as it is seeing that in error. That would be extremely rare though.
The way to test the computer for the injector signal is as above.... perhaps that code was set during your testing and was not originally there? If that could be the case, clear the fault and see if it returns.As for the P0302... if the injector circuit fault doesn't return then we would want to proceed with standard diagnosis.... swap the spark plug with an adjacent cylinder and see if the misfire moves. If it doesn't try a different plug wire and see if it goes away, if it doesn't then compression test the engine and look for a variance on cylinder 2.