Replaced DPFE Sensor, new misfire. Thoughts?

[MongooseGA]

Hey all,

(1999 3.0 V6 2WD FFV)

Thanks to searching this forum based on a P1400 (or 1401) engine code, I learned that the DPFE sensor was bad. Had the problem verified by my neighbor who is a commercial Ford Mechanic.

Anyway, went to my local Advance Auto and got the part. Swapped it out, and now I've got a misfire in the first cylinder. I believe it was code 0368 or something similar.

I can't really think of a reason there'd be a misfire immediately after replacing the sensor. It ran nice and smooth before, and obviously a bit rough now. Unfortunately my neighbor is out of town so, I turn to the experts here for some insight.

I have not yet pulled the plug to check that. Honestly, I don't know which cylinder is considered #1.

Any help would be appreciated.

Thanks,

G.A.

 

[ForOffRoadDriving]

no 1 is going to be the cylinder closest to the front of the crank (the first cylinder on the passenger side of the engine in this case) i would first pull the plug and observe its condition, then if possible switch plug wires with one from another cylinder (gotta find one thats close to the same length to swap with). start the truck up and see if the mis fire has moved to the cylinder you swapped the wire with, if it has then you have a bad wire, if not its going to get more complicated.

 

[MongooseGA]

no 1 is going to be the cylinder closest to the front of the crank (the first cylinder on the passenger side of the engine in this case) i would first pull the plug and observe its condition, then if possible switch plug wires with one from another cylinder (gotta find one thats close to the same length to swap with). start the truck up and see if the mis fire has moved to the cylinder you swapped the wire with, if it has then you have a bad wire, if not its going to get more complicated.

Aside from the things you mentioned, what else could it be? I wouldn't think distributor since it's only the one cylinder, but I could be wrong.

Thanks.

Update. I just did a quick swap back to the original DPFE sensor, to make sure it wasn't related to the misfire or anything else. The engine light came back on, presumably for the bad sensor. Misfire persisted with the old sensor.

Swapped back to the new sensor and disconnected the battery. Starts up with no engine light again.

 

[TimR]

distributor??? what distributor?

 

[MongooseGA]

distributor??? what distributor?

Oops, sorry. I meant coils.

I'm a bit of a mechanical layman.

I just took the plug out and tested the gap. It was a little narrow compared to the .44-.46 specs I found, so I opened it up with my gap tool. It is sparking when I tested it while bumping the key. It does seem that gapping it correctly may have smoothed out the idle a bit, however under very light load there's hesitation and a bit of shaking, under moderate load it smooths out.

 

[Baseranger]

Swap the plug wire and plug from cyl 1 to cyl 2 and see if the misfire code follows it. P0301 is cyl 1 p0302 is cyl 2 misfire codes.

 

[ForOffRoadDriving]

it should have a single 6 teminal coil pack (94 was the last year for a distributor ignition on the 3.0l) , so its going to be either good or bad. its most likely that you have a plug wire that is leaking spark and grounding out or it has built up enough internal resistance that it is missing.

 

[MongooseGA]

Swap the plug wire and plug from cyl 1 to cyl 2 and see if the misfire code follows it. P0301 is cyl 1 p0302 is cyl 2 misfire codes.

I was going to do this, except the computer isn't throwing a light for the misfire now. Once I cleared it after I put the new sensor on, it hasn't come back.

Thinking about it though, the code that specified misfire on cylinder #1, I don't remember it being p0301. I remembered it being something like 0368, which is the cam-shaft positioning sensor.

Would a bad CPS cause a misfire in a specific cylinder? What symptoms would it show?

 

[adsm08]

Swap the plug wire and plug from cyl 1 to cyl 2 and see if the misfire code follows it. P0301 is cyl 1 p0302 is cyl 2 misfire codes.

Don't do that.

Swap it across the coil at the pack. You have a waste-spark system and the two plugs on a given coil are paired and fire at the same time. If you swap them and the miss moves with the swap you need a coil pack.

 

[adsm08]

I was going to do this, except the computer isn't throwing a light for the misfire now. Once I cleared it after I put the new sensor on, it hasn't come back.

Thinking about it though, the code that specified misfire on cylinder #1, I don't remember it being p0301. I remembered it being something like 0368, which is the cam-shaft positioning sensor.

Would a bad CPS cause a misfire in a specific cylinder? What symptoms would it show?

Wait, if you don't have a P030X code, how in the world do you know which cylinder is misfiring? Unless you got your neighbor to run a power balance or a mode 6 check.

And while not impossible, it is not likely for the CMP (cam sensor is not abbreviated "CPS") to cause a single cylinder to miss, it is not 100% impossible.

 

[MongooseGA]

Don't do that.

Swap it across the coil at the pack. You have a waste-spark system and the two plugs on a given coil are paired and fire at the same time. If you swap them and the miss moves with the swap you need a coil pack.

Maybe I'm missing something, but it looks like I only have one pack and all of the wires are attached to it.

Wait, if you don't have a P030X code, how in the world do you know which cylinder is misfiring? Unless you got your neighbor to run a power balance or a mode 6 check.

And while not impossible, it is not likely for the CMP (cam sensor is not abbreviated "CPS") to cause a single cylinder to miss, it is not 100% impossible.

Honestly, it may have been, but in my memory I think the number was different. It had to have been 0301 though, since the scanner specified 1st cylinder misfire on the screen.

I just took the plug out and tested the gap. It was a little narrow compared to the .44-.46 specs I found, so I opened it up with my gap tool. It is sparking when I tested it while bumping the key. It does seem that gapping it correctly may have smoothed out the idle a bit, however under very light load there's hesitation and a bit of shaking, under moderate load it smooths out.