I’ve posted this already but I have new updates so I figured I’d do a new thread. I own a mustang 02 v6 coupe I’ve been having a very weird misfire for the past 2 years almost. In the morning the car starts normal with no misfires nor any other issues. The problem starts when I’m stuck in traffic let’s say for 10 mins my rpm drops and the engine hesitates/shakes it looks like the car is about to shut down. Another example when I turn it off and turn it back on after let’s say for 10 mins the car will start however the rpm will keep on dropping and it doesn’t really matter if I hit the gas pedal or not. If I hit the gas pedal it will take little to no gas and if I don’t hit the gas pedal it will just die on me, I’ll have have to wait for about 30mins to an hour for it to work again. Don’t get me wrong it will work but dies right after I won’t even have time to press the gas pedal. I’ve changed bunch of stuff with no success. I’ll attach the latest check engine codes.
Anytime the DTC code calls out a "circuit malfunction" this means there is something sooooooooo wrong with the circuit that the PCM is unable to perform any useful diagnosis. Think:
Totally bad sensor.
bad, loose, corroded, wet sensor connector
short to power or short to ground
wiring fault such as open or short to each other.
P0190 is either a bad Fuel Rail pressure sensor (FRPS) or a wiring/connector fault to/from the FRPS.
Have you performed a compression test on cylinder #4? Even better. How about the whole motor?
What have you done to rule out a bad, cracked, loose, separated crank damper? Any under drive pulleys?
What have you done to rule out a problem with the CMP (cam) sensor?
Are you POSITIVE that the battery and charging system is rock solid? And having a new battery or new alternator does not mean there can't be a loose connection somewhere causing unstable voltage. The voltage needs to be monitored while the event is occurring. You may not believe this but something as basic as a bad battery can "cause" the motor to die for no apparent reason. If you think that isn't possible because the motor is running, then much of the trouble shooting battle has already been lost.
What have you done to confirm that the IAC is working and the PCM is able to control the idle?
What have you done to rule out excessive EGR flow?
Note, there is a possibility that the lean DTC could be "caused" by the FRPS. However, you won't know unless the FRPS and long/short term fuel trims are monitored. What you are looking for is IF the Fuel pressure is changing (increasing) when this problem occurs. This would cause the PCM to pull back fuel thus making a lean condition.