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Duratec Misfire

R

rickl

New CEG'er
Joined
Feb 16, 2010
Messages
15
I have been struggling with this problem for a week and I hope someone can help me.

1998 SVT Duratec V6 MTX - 66k miles

The engine started started missing badly a week ago. It had original spark plugs and wires so I replaced them with Motorcraft wires and plugs. No change at all. CEL is on and flashing -- codes p0301, p0302, p0303. So all cylinders on the firewall side of the engine appear to be misfiring. I replaced the spark plug wires one at a time, so I know they are correct -- I checked and re-checked. I can pull any one of the 6 spark plugs from the coil pack and the idle changes considerably. So it appears the cylinders are firing, just not firing well. The coil pack tested good, but I replaced it anyway and that made no difference, so I put the old coil pack back on. It was a long shot, but I replaced the fuel filter and that made no difference. I have searched for vacuum leaks and found none. I do not hear the vacuum "hiss", but I sprayed carb cleaner anyway at suspected areas and found nothing.

The only thing that seems out of order is a "puff puff" sound at the top of the engine. It sounds like it is coming from below the UIM just behind the throttlebody. I am really out of ideas and am hoping someone on this forum has seen something similar and can give me a clue.

Thanks...Rick
 
Pull the 3 large connectors by the passenger side of the motor apart and click them back together. Just see if that helps at all.
 
I pulled two of the three connectors (black) and coated them with di-electric grease.

I was never able to get the bottom connector (gray) apart. I noticed there were bare wires on both sides of the connector and after messing with it trying to get it apart, a lot of the remaining insulation has crumbed away. Now I have at least 3 wires on each side of the connector that are completely bare. The insulation has dried up and just crumbles when I touch it.

I think I just made things a lot worse. Now I have bare wires touching each other and I am afraid to even turn the key on.

Help!
 
OK, I finally got the gray connectors apart. I used electrical tape to cover each bare wire and put di-electric grease on the connectors. I am not happy with this repair, and it seems like a short term fix, but it's the best I could do.

After all this...the misfire situation remains the same. Still p0301, 302, 303.
 
Double check the firing order in case you switch a plug wire around.

Check the air box for critters as well. I had one take up residence in my air box and chewed the paper filter to bits. Had to clean the MAF on that one. Trapped said critter in a mouse trap two days later LOL!
 
Thanks for your response. I have double and triple checked the firing order. Upon your suggestion, I checked the aribox and air filter. All nice and clean.

I don't want to take it to the dealer, but I am out of ideas and I need my car. Anyone else have a suggestion?
 
I used Mororcraft AGSF-32FM plugs gapped to .054. I tried swapping one of the old plugs back in and and leaving the new wire, but did not notice a difference. Spark plug wire tester shows good spark on all 6 wires.
 
The only codes I have are p0301, 302, 303. And it's consistent. I can clear the codes and those three reappear within 5 minutes of starting the car.
 
I am wondering about the camshaft position sensor. I think the plugs are firing, just not at the correct time. But I am not seeing the 340 code associated with the sensor. Feedback anyone?
 
rickl said:
I am wondering about the camshaft position sensor. I think the plugs are firing, just not at the correct time. But I am not seeing the 340 code associated with the sensor. Feedback anyone?
Click to expand...

doubt it. if there was a crank sensor issue then the car most likely wouldn't start. also your only getting codes for one bank. only of the way this can happen is if the cams are not timed correctly. I'm going out on a limb and going to say the cams and timing haven't been touched.
 
BrApple -- thanks for your response. The cams and timing have not been touched. The only engine maintenance done (besides oil changes) prior to this misfire condition was in October 2009. The engine would not start at all and the cause was found to be a broken wire to the crank position sensor.
 
Ok now I'm REALLY going out on a limb here...

It's rather difficult to change the rear three spark plugs (cylinders 1, 2, 3), which are the misfires you have. MAYBE it's possible that those three plugs aren't properly or fully threaded? :shrug: :confused: :help:
 
I removed the coil pack and found the plugs were not difficult to replace at all. All three came out easily and went in easily. I just checked the firing order (again). Here is how the plug wires are attached:

<Firewall>

Coilpack
4 6 5
3 2 1

Engine
1 2 3
4 5 6

<FRONT OF CAR>
 
Hey I said I was really going out on a limb :laugh:. Many people have trouble negotiating the spark plugs on these cars, likely due to the tools they are using. Regardless, you have the correct spark plug firing order.
 
I checked and the ground strap is attached to the coil pack. Here are a couple of things to note:

1. Before I changed the plugs and wires, the car ran like crap and I was getting p0301, 302, 303 codes. None of this changed after replacing plugs and wires. The car still runs like crap and I am still getting the same codes. It seems like the problem may be somewhere other than plugs and wires.

2. I can remove any one of the six plug wires from the coil pack and the idle changes significantly. The change in idle does not seem to be any different whether I pull a wire from bank 1 or bank 2 of the engine. The plugs are firing, it just seems like they are not firing at the right time. Spark tester shows strong spark from all 6 wires.

Thanks for your input!
 
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