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02 Taurus DOHC misfire

CSVT#49

Addicted CEG'er
Joined
May 28, 2004
Messages
6,768
Location
Andover, MN
Alright so I got a call from my folks saying that my mom's 02 Taurus SES DOHC was having some issues. My mom had been using it for running some errands and after leaving the third store it started shuttering. They didn't know what it was, but my dad took it into an O'Reilly's and pulled the codes. Turned out it only had one code, which was P0316, which corresponds to misfire on startup.

So I went down to their house this afternoon and took a look at it. I pulled the codes again with my scanner and found that it was also showing P0301, which is misfire cylinder #1. So I had the following thoughts going into this...

1. Spark plug well full of oil
2. Spark plug fried
3. Plug wire fried
4. Coil pack fubar'd
5. Bad injector
6. Bad injector wiring

Alright so I pulled the UIM off and upon doing so found that there were splits in the rubber hoses for both the valve cover breather lines as well as the line for the EVAP system coming out of the UIM. I looked over all of the wires and plug wells and found no oil (scratch #1). I took all the plugs out and found nothing wrong with them (scratch #2). Took cylinder #1's plug wire and stuck a test spark plug in it and had one of my brothers ground the electrode and turned the car over, definitely got spark (scratch #3 and #4). Hooked all of the plug wires up and started up the engine (with the UIM off still). Looking down the LIM we compared the fuel injector patterns, all appeared to be operating the same and normally (scratch #5 and #6). So I put some dieletric grease on all the plug wire connections and placed new gaskets on the UIM and reassembled everything and in the process replaced the split hoses/elbows on the breather and EVAP lines. I then cleared all the codes and disconnected the battery. After taking a break for dinner I hooked the battery back up and started the car. Everything ran as it did before, unfortunately I could still feel and hear something wasn't running right. I drove the car around and it felt a little under powered, with the occasional hiccup ever now and then while driving around. The engine light however remained off through multiple start ups and test drives. I've heard of vacuum leaks causing misfires in some instances, but now with everything fixed I'm out of ideas. I'm thinking of buying a new set of wires and possibly a coil pack, but I don't want to just through parts at the car especially when I could find nothing wrong with those components. I went through the car about 3yrs ago when the rear back had an oil leak in the #5 plug well. At which point I replaced both valve cover and well gaskets, spark plugs, plug wires, fuel filter, air filter, UIM gaskets, ATX filter & pan gasket, and did an oil change. Since then the car has had roughly an additional 60k put on it (putting 99,938 on the odometer).

So I am out of ideas and would be interested to see what all of you think I should look into next.
 
You may want to check the PCV rubber connection to the UIM. The elbow part becomes clogged and the rubber deteriorates from the inside out.
I have found that was the issue on a friends Taurus.
If you need one, I have a spare in the garage

tauruspcv..jpg
 
You may want to check the PCV rubber connection to the UIM. The elbow part becomes clogged and the rubber deteriorates from the inside out.
I have found that was the issue on a friends Taurus.
If you need one, I have a spare in the garage

View attachment 9296

Actually that already happened :( and I forgot to mention that in the history.

My brother fixed that on her car about a year ago. The rubber elbow had completely ripped just as the breather lines did. However when I took the UIM off I did not check that line again to see if it was clogged. Good to know about your spare though. I'm back up at my house, which is 45min away from my folks place. My brother does still live with them though so I might ask him to take a peak at that line again just to check that it isn't clogged.
 
I went through something like this my 01 Sable DOHC , after replacing plugs, wires, filters, gaskets, ect. turned out to be coil pack, seems to be a common issue on this era 3.0 Tarus /Sable. Good luck with it, hope you get it sorted out.
 
I thought the coil pack could be the issue too... but it's odd because if that was the case you would think that, 1. I wouldn't get spark out of the plug wire at cylinder #1 and 2. There would be a misfire on another cylinder as well since the coil drives two plug wires with the waste spark system.
 
Yeah that seems like that would be the case, but on my mine I was getting only a single cylnder missfire as well (P0301), the coil wasn't cheap but it did fix it.
 
Throw a set of plugs in it and clear the codes. Should take care of it. And to answer your question, yes, a vacuum leak can cause a misfire.
 
I do these issues all day, replace plugs and wires with Agsf32fm gapped to .054, take 2 old wires and rip the rubber 90 off, then remove metal coil pack insert so air can flow, these are your new valve cover nipples, use hose clamps on the air/oil seperator hose x2, make sure its turned to the right fully and clicked to seal...reassmble and test drive, issue remains, replace coil pack...issue remains lemmie know! ;)

Steve-O
 
I do these issues all day, replace plugs and wires with Agsf32fm gapped to .054, take 2 old wires and rip the rubber 90 off, then remove metal coil pack insert so air can flow, these are your new valve cover nipples, use hose clamps on the air/oil seperator hose x2, make sure its turned to the right fully and clicked to seal...reassmble and test drive, issue remains, replace coil pack...issue remains lemmie know! ;)

Steve-O


Say what?! LoL.

The breather lines are already fixed. Plug wires are only 3 years old and are OEM Motorcraft wires, which I picked up at the dealer via Tousley Ford. I'm guessing it's the coil pack. We're not seeing codes anymore, but the engine definitely still shutters every now and then. My brother and I are searching the web for the best deal on a new coil pack. Hopefully that fixes the problem as it wont be cheap.
 
You can also spray water on the coil and the wires to see if they are arcing across anything

Not a bad idea. We already watched the engine in the dark to see if we could see any arcing. Might not hurt to throw a little water mist at it.
 
I went through the exact same issue with my '96 Contour 2 weeks ago. I had a P0304 code (misfire in cylinder 4). I replaced the spark plugs, spark plugs wires and coil pack. At one point, I thought my catalytic converter was clogged. So I got rid of my stock exhaust manifold and got new headers and a new universal catalytic converter. But the car continued to performed sluggish as well as the code kept coming back. As it turns out, the fuel injector in cylinder 4 simply went bad. I then went to the junkyard and bought a used fuel injector and installed it. The problem was gone.

Based on my experiences, my recommendation is to take a look at the fuel injector in cylinder 1 and replace it if necessary. I hope this helps.:)
 
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