[4th Gen : 01-07]: P0301 & p1794 codes
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P0301 & p1794 codes
I have a 2006 Dodge grand caravan 3.8 140k. Since june 2018 I've been having engine code issues repeatedly. PLEASE HELP. . P0301 Misfire cylinder 1. I've replaced the soak plug, wire and coil pack. The code continues to come on and van still continues to startup rough and idle rough from time to time and each time it kicks the code. Next web this started in June I also had Transmission codes P0700 reading faulty input and output transmissions sensors. asa I replaced them, they read faulty again. After replacement from dealer parts the van then began reading code p1784 for SPEED SENSOR GROUND ERROR..WELL WHAT IS THAT IN LAYMANS TERMS? ?? I've looked everywhere and have no clue even where to start to fix this or what else the issue could possibly be with the p0301 code or if there's a wire exposed in one of the harnesses the link the two that I'm unaware of. .PLEASE PLEASE HELP ME. .This is my only means of transportation. THANK YOU FOR ANY ASSISTANCE YOU COULD OFFER.
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P0301 - There's more to misfire diagnosis than just ignition, but since you've already replaced the spark plug, what did it look like? Use this link to determine what potential problems there may be by how the spark plug looked - https://www.aa1car.com/library/reading_spark_plugs.jpg And did you replace the other spark plugs and wires as well? If not, do it, because replacing just one spark plug is not recommended unless a new plug has been ruined somehow.
Test for intake leaks by spraying carb cleaner around the gasket areas for cylinder number 1 - if the engine RPM changes, the gaskets are leaking.
Have you noticed that coolant seems to disappear but there's no signs of a leak? Have you noticed any white smoke on start up, whether it's cold or not? If yes, it's possible the head gasket is leaking. Run the engine to operating temperature, then shut it off and remove the spark plug. If you hear a hissing sound or if you can see into the spark plug bore, look for signs that coolant is filling the combustion chamber. If it is, the head gasket is leaking.
Compression test all the cylinders and see how #1 compares. They should all be at least 100 PSI with no more than 20% variation from the highest to the lowest reading.
Misfires can be caused by electrical as well as mechanical problems. You need to methodically diagnose each side to determine the root cause.
P1784 - The speed sensors are like any other circuit in a vehicle - they have a power/reference circuit and a ground circuit. This code means that the computer is not seeing the ground signal (also called a low ref) from the sensor. There's either an open (break) in the wiring between the sensor and computer or there's an issue with the connectors. You'll have to inspect the wiring for problems between the sensor and computer using a meter.
If you're uncomfortable at all with these tests, I really recommend you take it to a shop, whether it's a dealer or not. Most independent shops won't charge you for diagnosis unless it takes more than an hour and you can be very clear that you don't want any repairs performed without an estimate first.
Test for intake leaks by spraying carb cleaner around the gasket areas for cylinder number 1 - if the engine RPM changes, the gaskets are leaking.
Have you noticed that coolant seems to disappear but there's no signs of a leak? Have you noticed any white smoke on start up, whether it's cold or not? If yes, it's possible the head gasket is leaking. Run the engine to operating temperature, then shut it off and remove the spark plug. If you hear a hissing sound or if you can see into the spark plug bore, look for signs that coolant is filling the combustion chamber. If it is, the head gasket is leaking.
Compression test all the cylinders and see how #1 compares. They should all be at least 100 PSI with no more than 20% variation from the highest to the lowest reading.
Misfires can be caused by electrical as well as mechanical problems. You need to methodically diagnose each side to determine the root cause.
P1784 - The speed sensors are like any other circuit in a vehicle - they have a power/reference circuit and a ground circuit. This code means that the computer is not seeing the ground signal (also called a low ref) from the sensor. There's either an open (break) in the wiring between the sensor and computer or there's an issue with the connectors. You'll have to inspect the wiring for problems between the sensor and computer using a meter.
If you're uncomfortable at all with these tests, I really recommend you take it to a shop, whether it's a dealer or not. Most independent shops won't charge you for diagnosis unless it takes more than an hour and you can be very clear that you don't want any repairs performed without an estimate first.