Just bought a 04 Dakota...3.7/5Spd M/120,000KMs. The truck is in great shape..obviously well cared for. Lots of power, but the engine has a rough idle and sounds like a diesel when cold. Ran Lucas injector cleaner through it...improved a bit, but still a tad rough....I'm thinking of doing a reset, but afraid of making matters worse....any suggestions out there.

 

No harm in doing a reset. Let it sit for an hour or so with the battery disconnected. I would start with a basic tune up too (plugs, wires, oil change, air filter, PCV, etc) if that has not been done already.

 

check if its throwing any codes.

 

Definetly do the reset; you wont hurt anything.

Sounding like a diesel when cold is normal for any engine if its in the teens for the temperature and the truck has sat overnight. Injectors are noisy when cold, and the lifters will make noise until they are fully lubricated. I recommend you let the truck run for 1-2 minutes before you start driving it.

For the rough idle, you can try swapping the spark plugs to a range colder. This helps alot of the 3.7/4.7l rough idle issues, but sometimes it doesnt solve the issue all the way. A rough idle could be plugged injectors, bad O2 sensors, a bad tank of fuel, ect.

 

Great advice all...thanks. No codes...."P-done"...have not changed spark plugs yet. Did change the oil but will continue with a basic tune up.I did put a bottle valve cleaner in. Still rough idle but ticking noise has lessened.... lots of snap now. Got some air intake cleaner and will try that too. Also, our province is being sold on ethanol by the local oil refinery and everyone has jumped on the band wagon. As of March 8 we have 2 new grades of ethanol gas to replace regular. Soooo...I put a tank of high test ethanol free in.....and the ticking greatly subsided in a 15 mile run....I'm thinking the noise is injector tick which may get better as I cycle through the tankful. I still will do a reset....do any of you guys have the steps involved?

Big Thanks.
Linz

 

disconnect the battery for at least 20 minutes. I do mine every now and then, just disconnect overnight. Runs like a new truck every time.