Unexplained Engine Problems (P0300, Unexplained Coolant Loss and Cruise Control Not Activating

[Dustin Moldthan]

I have a 2005 dodge ram 1500 slt quad cab 4.7 Engine non-flex

For the past 2 months, I have been having a p0300 misfire code (random intermitted misfire) and sometimes it will throw in a p0307 (cylinder 7 misfire) code. I have replaced my spark plugs in all my cylinders and replaced the ignition coil for cylinder #7 and still getting codes. My truck seems to misfires only when she is on a cold start. I can drive to Autozone and wipe the code and drive for hours with no codes pop up. Also when I wipe the code, I won't get the check engine light for about 4 days Back when I first bought this truck, I had the valve cover gasket replaced.

My coolant seems to be disappearing with no visible leaks anywhere. My truck had no heat so I replaced the thermostat and flushed the coolant system. I also replaced the water pump. The previous owner did put stop leak in the coolant system before I bought it. I have seen white smoke come out of the exhaust once but that was on a cold morning. (45 degrees or so). I also used to hear a bubbling noise when I accelerated but I haven't noticed it recently.

Now, this may be or may not be related but I wanted to put this in here as well. My cruise control will turn on and I can see it is on via the dash but it will not set.

This is possible stuff I think it could be but I could be wrong and wanted your insight on it. Intake manifold leak (or a vacuum leak in general) and a blown head gasket. If you guys have any other ideas or know how I can test to see what it is, I would really appreciate it.

 

[GTyankee]

Maybe when you have a stored trouble code, the Cruise Control is disabled

You could do a engine Compression Test & a valve Leak Down test to check out the engine itself

You can also do a radiator combustion leak test, you rent one of these at places like AutoZone or Oriellys

watch this video, it sounds similar to the issue that you are having

They are testing a diesel, but testing a gas engine is similar

 

[MikeT]

This probably won't be of much help, but I'll give you what I've got. My wife has a 2007 Dakota with a 4.7. For about 2 years she would loose about a quart of antifreeze in about 500 - 600 miles. No drips anywhere ever. One day I found a couple of drops up front of the truck. Checked the upper radiator hose and found it loose. Tightened all the hose connections and no more leaks. Moral: Check the simple things first, which of course I didn't do.

Mike

 

[Fast69Mopar]

I have a 2005 dodge ram 1500 slt quad cab 4.7 Engine non-flex

For the past 2 months, I have been having a p0300 misfire code (random intermitted misfire) and sometimes it will throw in a p0307 (cylinder 7 misfire) code. I have replaced my spark plugs in all my cylinders and replaced the ignition coil for cylinder #7 and still getting codes. My truck seems to misfires only when she is on a cold start. I can drive to Autozone and wipe the code and drive for hours with no codes pop up. Also when I wipe the code, I won't get the check engine light for about 4 days Back when I first bought this truck, I had the valve cover gasket replaced.

My coolant seems to be disappearing with no visible leaks anywhere. My truck had no heat so I replaced the thermostat and flushed the coolant system. I also replaced the water pump. The previous owner did put stop leak in the coolant system before I bought it. I have seen white smoke come out of the exhaust once but that was on a cold morning. (45 degrees or so). I also used to hear a bubbling noise when I accelerated but I haven't noticed it recently.

Now, this may be or may not be related but I wanted to put this in here as well. My cruise control will turn on and I can see it is on via the dash but it will not set.

This is possible stuff I think it could be but I could be wrong and wanted your insight on it. Intake manifold leak (or a vacuum leak in general) and a blown head gasket. If you guys have any other ideas or know how I can test to see what it is, I would really appreciate it.

My educational internet guess is that when the truck sits overnight for a cold soak, the pressure in the cooling system is pushing coolant past a head gasket on cylinder #7 or multiple cylinders and on a cold start the misfire is detected because there is coolant in the cylinder. Once the combustion process begins to warm up the engine the coolant is burned easier and the PCM does not detect the misfire. I have repaired too many 4.7's that have the same symptoms as you.

 

[EdGs]

One thing you can check:

After the vehicle has sat for a day or two (if possible), loosen the oil drain plug just enough for it to start dripping. If there is coolant in the oil, it will show very quickly in the drip as oil floats on water.

Oops, guess I'm a bit late to post this....lol