ive been working on a neon for my step dads car lot. It starts up and runs for like ten seconds and then the engine dies. ive checked fuel pressure, and changed fuel filter and the coil. no idiot lights are on. it starts up and runs like you just disconnected fuel pump relay. If you press the gas when its started itll instantly die. Im think of checking maybe knock sensor or timing ,idle air sensor. any help would be appreciated. its an 2001 neon with the 420a

hmm...interesting problem...what you need to do is pinpoint whether its a spark problem or a fuel problem and go from there.. cuz its possible for it to be either, even tho the fuel pressure is up to snuff( it is isnt it?) easiest way to do it that i know of is go to wal-mart, buy a can of super tech carb cleaner (basically straight acetone in an aerosol) and start it and give it a shot of that and see if it stays running when it would normally die... if it does die its a spark problem...if it stays running on the acetone, then you know its fuel. and go from there. my .02

ill try that.

i ran an obd2 scanner on the car and it said that the air/fuel mixture malfuction. What other sensors have to do with air/fuel. I know an 02 sensor is not going to stop the car from running. neither should idle/air. If anyone has any suggestions hit me up? i think im overlooking something.

Could be a sticking injector? Got another set you could swap out? Fortunately, it takes all of fifteen minutes to replace the injectors on a Neon.

Could have enough flow for idle, but applying throttle causes a lean condition and the ECU shuts things down. (based on 02 reading, maybe?) I know that you can throttle up an engine with an injector stuck open, as it will idle like shit (nearly flooded, or flooded in one cylinder), but things will smooth out once you reach the engine speed at which that cylinder is seeing the right amount of fuel.

Just an idea...

ASD Relay?

as far as sensors that have to do w/ air/fuel ratio...it could be a map sensor or something too...but another thought i had is use your OBD2 scanner and see what your coolant temperature sensor is saying...ive had a few vehicles come into my shop that wouldnt run cuz the engine thought it the coolant was -60 degrees...and it totally messed up the fuel trim because it was trying to compensate for the supposedly cold temperatures by overfueling...but yeah w/ the map sensor, make sure the static pressure reading is correct for your elevation, if it isnt...that might be the problem too.