Engine misfire issue

After changing my thermostat out in my 2005 Jeep Grand Cherokee 3.7L V6 the car still began to overheat. I would bleed it and think it was bled and sadly it would run hot again. But I never let it get into the red. After it cooled the last time I drove it home and at one point I heard a knocking noise and my truck started to loose power. I let it sit for a day and when I crunk it up the next day my checking engine light was flashing. It didn’t make the same loud knocking noise and with the hood down you can’t even hear it. All the action came from the way it drives. It doesn’t accelerate fast sometimes and sometimes it does. When it doesn’t accelerate fast it chugs like a train and it jumps and skips real hard to get to the needed rpm to change gears especially going up a hill but then there are moments when it’s perfect and the check engine light doesn’t even flash. The truck does smoke from the passenger side of the engine. There isn’t a milky mix coming from the dipstick and no white smoke from exhaust pipe and also there appears to be no loss in coolant in the reservoir. Lastly the truck isn’t overheating and the heat and air works fine unlike before when the thermostat was out. So could it be a blown head gasket or could it be spark plugs or something fuel related.

That means - Don’t Drive The Car, something really bad has happened. Is it still flashing? Can you read the error codes or get someone to do that? If you can, post them here… in the form P1234. If you intend to have someone else fix it, I recommend towing it there.

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The codes I got were P0300,P1637,P0138,P0522,P0420

The P0300 is a general misfire problem, could be cause by the other codes

Your alternator has a problem - P1637 code, could be any of these causes;
P1637 Chevrolet Possible Causes

  • Faulty Generator (Alternator)
  • Generator harness is open or shorted
  • Generator circuit poor electrical connection
  • Powertrain Control Module (PCM) programming
  • Faulty Powertrain Control Module (PCM)

A code P0138 may mean that one or more of the following has happened;
Faulty O2 sensor
Short to battery voltage in O2 sensor signal circuit
High fuel pressure (not as likely)

Symptoms of a P0522 DTC may include:

Oil pressure gauge reading low or zero
Oil pressure indicator lamp illuminated
Engine may not start Engine may quit or stall while driving

And finally

P0420 Possible Causes

  • Faulty Three-way Catalyst Converter Bank 1
  • Exhaust Tube
  • Intake Air Leaks
  • Faulty Oxygen (O2) Sensor
  • Faulty Fuel injector(s)
  • Leaking Fuel Injector (s)
  • Faulty Spark plugs
  • Improper Ignition Timing
  • Faulty Engine Control Module (ECM)
  • Dirty Air Filter

Check the oil pressure with a mechanical gauge on this engine as a first step. If there is low of no oil pressure, none of the other problems will matter as the engine will lock up and die.

Next look into the alternator next. Might be a bad alternator, might be a bad PCM.

This is a serious bunch of problems you have here. This would be a challenge to a professional and almost impossible for a shade-tree mechanic. I’d suggest professional help.

He has another thread on this same car with other problems also

All these issues resulted from the misfire. None of the codes from before are showing up.Thank though.

The P0300 misfire could result from a vacuum leak or lack of fuel pressure.
If the engine idles real low due to the misfire that could cause low oil pressure and alternator output.

Is it fixed, then?

Depending on the cause of the misfire, they could all be related. A blown head gasket, for instance, could cause overheating. If it causes a misfire (possible) the O2 sensors will read out of spec due to unburned fuel.