Misfires, cant find the problem.

[Chadrax]

1997 Ford Explorer SOHC 4.0L.

Codes: P0305(pd), P0306(pd), P0305, P0306. (Anyone know what the (pd) is?)

Scenario: I start my car and start driving. Everything is fine. Five minutes later, I feel the car shaking at low rpms (After a stop sign, or stop light). Then it starts shaking at higher rpms a few minutes later (70km/h+)

At the start if I try and pull the codes I get nothing. After I feel the initial shaking I get the codes P0306(pd) and P0306.

After it starts shaking at 70km/h, I pull the codes again and I get P0306(pd) and P0306, P0305(pd) and P0305. The codes wont go away until I start the car again and clear them, then the cycle repeats.

Pulled #4 plug, put it into #5 cylinder, same thing. Switched the wires as well.

Car was running fine one day, and then this the next.

Any ideas?

 

[mstrmp3]

weak coil? I had the same problem, changed it out and no problem again.

word of caution, I went to Autozone and got a Duralast coil, it didn't last 2 months. Finally broke down and got a Motorcraft one.

 

[corkey]

could be bad coil, bad plugs or bad wires, or could be clogged injectors,, run some injector cleaner through it too,

 

[69Mach1]

I "think" the (pd) means Pending. The computer is deciding if it's a one time hick-up or an ongoing problem.

 

[wicsmith1997]

I recently experienced this after filling up with a tank of gas. Don't know if bad gas set it off, or was just the final straw. I replaced fuel filter which didn't fix my issue but may fix yours if its clogged, Cleaned the cylinders with Seafoam ran into where the pcv valve goes in; this helped but still had the miss. Replaced Plugs (motorcraft) and Wires (autolite) and then cleared the computer so it can relearn its driving program.

My situation was worsened by a thermostat stuck open not allowing engine to warm up to efficient running temp so also replaced it while doing the plugs.

 

[NCTuskie]

I'm having a similiar issue. I just replaced the coil pack with a Duralast from Auto Zone. Its about a week old. It didn't seem to help the problem. The plugs and wires, as well as thermostat are all less than a year old. I'm also experiencing issues with the engine not heating up (either a bad thermostat or a bad temp gauge).

I'm pretty certain I had the fuel filter replaced within the last year, but I cannot say for sure. As easy fixes as they are, I'll swap both the fuel filter and thermostat and see what happens.

 

[wicsmith1997]

@NCTuskie what brand wires and plugs. All on this board are people saying stick with Motorcraft or Autolite. if you are having a miss in a specific cylinder try switching a nearby cable and see if the miss changes to the new cylinder there by confirming its the wire.

 

[Chadrax]

Coil pack replaced, car seems to have more power, but has the same problem. I guess it was time to replace that anyways, the oldone had about 250,000k on it. Just put 2 bottles of injector cleaner in, seeing if that will help.

I have noticed the temperature guage in the car was only going about 1/3 of the way to hot. Normal, or time to replace thermostat?

Edit: Fuel filter replaced a few months ago. Cylinder 5 misfire seemed to go away for the time being, maybe it was the fuel cleaner, not too sure yet. Ill update this with any information I get.

 

[Chadrax]

Cylinder 5 came back. Tried plugging the EGR, nothing. Tried pulling the maf sensor, thinking it may be an air intake leak somewhere after the MAF, and cylinder 1 and 3 started misfiring as well..?

Im all out of ideas at this point.

 

[2000StreetRod]

CKP sensor?

Multiple misfires on non-adjacent cylinders may be due to a faulty crankshaft position sensor. You might try disconnecting and reconnecting the electrical connector to clean the contacts. Engine misfire procedure

 

[Chadrax]

Cant seem to find the CKP sensor. Looking down from the top of of the engine, where would it be?

Edit: Realised I wouldn't be able to see it from the top. Ended up going through the passenger side wheel to get to it. I'll report back after a test drive later today.

 

[Chadrax]

Cleaned the sensor, didn't help. Now also getting a misfire on cylinder 3. Maybe it's time to get the injectors professionaly cleaned, or another issue?

 

[Chadrax]

Checked again today. Now misfires on 1 and 6...Anyone?

 

[NCTuskie]

@NCTuskie what brand wires and plugs. All on this board are people saying stick with Motorcraft or Autolite. if you are having a miss in a specific cylinder try switching a nearby cable and see if the miss changes to the new cylinder there by confirming its the wire.

@WICS

I'm not sure about the plugs, but I bought Duralast Wires from Autozone, along with the a Duralast Coil pack. I'm still having fuel consumption issues, along with misfires, and trouble downshifting.