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Discussion Starter · #1 ·
Problem: At low RPMs and idle the car has occasional misfires, sometimes barely... other times quite a lot, mostly when hot. When it really acts up I have to floor it in order to get moving. Otherwise it chokes and sputters until I attain speed.

I've checked for vacuum leaks everywhere with TB cleaner and no apparent leak was found. I sprayed EVERYWHERE, especially around the IAC and intake manifold.

I checked the EGR valve by applying vacuum at idle and the engine drops to stall as expected, so EGR valve is not stuck open.

I thought about the coils but everyone keeps saying once a coil goes bad it'll keep misfiring all the time. My car occasionally goes like 2-3 days at a time purring like a kitten then BAM, back to square one.

I cleared all codes this morning and drove to and from work (about 50 miles) then went to Advance to get the codes read. Believe it or not, with all that bucking and jarring the only code found was P1401.... for the SECOND time in a row. (had it checked Monday as well).

Obviously the next step is to buy the DPFE, which I'm going to do 2morrow B4 work. My question, though, is CAN a bad DPFE cause such problems.. escpecially at idle when the EGR system isnt even active? I would hate to buy this little $76 bugger and have the problem remain.

SUMMATION: Can a bad DPFE can cause such problems?
 

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sure can got the same symptoms on mine. but i got a bad brain i think still playing with it. who know because it has been in a accident before i bought it.
 

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yes - i had these problems with my 2002 Duratec - though not quite severe as yours. Also the P1401 code. I replaced the DPFE, PCV valve & hose - and the problem is gone. So I'm not sure which actually solved the problem.

You can get the DPFE on rockauto.com for $32.79 - and all 3 parts for less than the $76 you are being charged. Stick with the Motorcraft parts.
 

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Discussion Starter · #4 · (Edited)
Well, $80 down the drain!!!!! I installed the new DPFE from the dealership... still bucking and shaking. Damn, this sucks!

I wanted to add a side note. I forgot to mention that whenever the car does the stutter/bucking/jolt/hesitation, there is a coinciding crackle on the stereo speakers (if my radio is on) and I can see my headlights and interior lights dim, exactly with the drops. Not sure if that adds anything valuable.
 

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Well, $80 down the drain!!!!! I installed the new DPFE from the dealership... still bucking and shaking. Damn, this sucks!


that why i hate obd2 i replace my dpfe 4 times and the dpfe solenoid and the egr and still have the p1401 i end out buying a alldata for a year. found out threw testing the p1401 is linked to a high out put from the brain so it is eiter a wiring issue were a wire is melted togather. or the brain is high outputing to much voltage on the voltage refference pin for the dpfe .
 

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Discussion Starter · #6 ·
I too am suspecting something in the wiring, especially due to the effects on the electrical components I mentioned above.

Another thing I should mention, that I forgot about since it's been a while: about 2 months ago my alarm began to go off for no reason. The car would be paarked in the driveway and all of a sudden it would start going off. Also, sometimes at night I would see the dome light on.I eventually removed the bulb because I was afraid it would come on at night and drain my battery. I just use the switch lights instead.

Also, my EATC is on the blink... The blender door stopped working (though I wired a jumper wire directly to it and use it with 12V from the cig. lighter to manually change from hot to cold, so I know the actuator itself works).

I dont know if all this weird stuff is related to the misfiring, but now that a new DPFE didnt fix it I guess I'll have to check other pathways. My next step will prob. be to chech the PCV valve. Any tips on getting it off? I see a big coolant hose in the way and a bundle of cables.
 

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Discussion Starter · #7 ·
Drove to work today. The car behaved great. Coming back home... HORRIBLE. Could barely gain speed on the highway ramp. Amazingly... no CEL yet. No codes. I guess the DPFE really did need to be replaced. Unfortunately, it's failure had nothing to do with my ongoing problem.

I'm just hoping for a new code... something that will lead me in some direction instead of blindly checking every possible thing.
 

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04 Bad miss

I got a 2004 3.0 OHV that misses at idle,worse at speed. Takes for ever to shift each gear, with pedal on the floor. Replaced the upper and lower intake gaskets. Replaced the plugs to, since they were easier to get to the rear ones {MotorCraft}.The miss gets worse with the a/c on. Checked all the fuel lines and hoses from the fuel tank to the injectors, no problem. Kicks check engine light. Reads multiple misfires across the cylinders, misfire in the coil secondary. I've had this problem off and on for two years. The dealership said on three different times that the computer is going. I've never seen one take two years to go out. The hotter it is the worse it is. Someone please help.
 

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Discussion Starter · #9 ·
Update: Well... six days later and I still have NO CEL but the misfire is still there. Like the member above, it's worse with the engine hot.

I'm glad the new DPFE sensor cleared the p1401 code but now I'm stuck with a misfire with NO CODE!!! Any ideas what would cause that? Logically speaking, that would mean that the faulty element is non-sensored, therefore not reporting any issues. But wouldn't a misfire eventually report a p030X code or at least a mixture rich code? I'm amazed that I'm not getting any codes at all.
 

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have you done a compression test to verify the mechanical integrity? a burnt valve or blown head gasket can cause the symptoms you are having and will not necessarily set a code.
 

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Discussion Starter · #11 ·
have you done a compression test to verify the mechanical integrity? a burnt valve or blown head gasket can cause the symptoms you are having and will not necessarily set a code.
No, I have not yet. I am trying to diagnose from simplest to hardest. But I guess that really SHOULD be one of my next tests. I guess I should start getting the tools ready for a compression test.
 

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No, I have not yet. I am trying to diagnose from simplest to hardest. But I guess that really SHOULD be one of my next tests. I guess I should start getting the tools ready for a compression test.
You can also use a vacuum gauge for a quick check. It can tell you a lot about the condition of your engine. Some of the oldest tricks are still the best tricks.
 

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Can you summarize the issues with the car...maybe I was out in the heat too long, but I see a lot of issues mentioned.

The alarm going off randomly is a sensor that has failed in a lock cylinder somewhere. Cheap fix is around that involves ungrounding a wire IIRC that disables the alarm.
 

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Discussion Starter · #14 ·
Can you summarize the issues with the car...maybe I was out in the heat too long, but I see a lot of issues mentioned.

The alarm going off randomly is a sensor that has failed in a lock cylinder somewhere. Cheap fix is around that involves ungrounding a wire IIRC that disables the alarm.
Here is a recap, Bull Geek...

For the past like 2 years or so, the car has had an annoying intermittent misfire. If I'm sitting at a red light, everything will be normal and then suddenly there will be a "thump"... then another "thump-thump". As it misfires it rocks the car front and back a little and I'll hear a crackle sound over my stereo speakers and all my lights will dim just slightly, in sync with the thumps. It is worse with the a/c ON...about 15 thumps per minute.... with the a/c OFF, about 10 thumps per minute.

The alarm issues are prob. completely unrelated but I just brought it up in case there was something which related it to the misfiring, but it's not really my concern in this thread. Just posted it as a reference. The main concern is this intermittent misfiring.

After having the codes read (only P1401, btw) I replaced the DPFE sensor and have not had any CEL anymore, though the misfires continue. New airfilter, fuel filter and platinum plugs have had no effect on the misfires.
 

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Hmmm OK. So DPFE has been dealt with. Next I would look at the EGR...is it filled up with carbon? I know a few members with older vehicles had their vehicles running like crap with this.

Next...coil on plug assemblies...take each one of them out , wipe them down and look for hairline fractures. Last summer I was having an intermittent miss when the car was under load, especially with the AC on.

If you want to a view a long drawn out video showing what I discovered, check this video I made...

New ignition coils solved it. There's a guy on eBay selling a 6 pack of coils for like $90. Or you can pay $40/piece (eBay) to $130/piece (dealer).

Not saying this will solve your issues, but I would definitely check them...
 

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Discussion Starter · #16 ·
LOL, BullGeek. Small world. We actually corresponded 2day on youtube. I recognized your video as soon as I saw the frame.
 

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Ohhhhhhh That was you! Well welcome board, lol!
 

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Discussion Starter · #18 ·
Interesting Update: I finally got my inline coil/spark tester today. I wanted to see if the coils were actually sending spark when the misfiring/bucking would happen. I waited till I got back from work when the engine was hot and the bucking was pretty frequent.

I started at the front driver-side of the engine and began placing the tester in-line. One by one, every coil was triggering the tester flawlessly - even when the engine missed. So far, all coils passed.

However, when I placed the tester on the second-to-last coil (rear-middle of engine) and turned the engine on, the car suddenly ran smooth. I waited and waited for a buck or stutter... but nothing. I turned off the car, removed the tester, placed the coil back on and turned on the car. Unbelievably.. the engine hummed smoothly. Again I waited and waited but no bucking...

So in summary:
-the engine was in its misfiring fit when I got home
-as I tested every coil, the tester showed spark on each cylinder, despite continued misfiring
-from the moment I removed the rear/middle boot the bucking was gone.

BTW, this is usually what happens when I remove/replace plugs. It'll miraculously fix itself then return to misfiring within a few days.

I'm wondering if there is some kind of cable grounding or shorting out and whenever I go back there and mess with it, it temporarily fixes it... until it comes to rest on whatever it is it's shorting on.

Interestingly, this rear/middle cylinder sits RIGHT in front of the DPFE sensor.... which if you read this thread from the beginning, was the opening subject. I got a P1401 code (high DPFE voltage).

So I guess my next step is to drive the car for a few more days until the bucking comes back, after which I will go DIRECTLY to the rear/middle cylinder, remove and replace the coil and see if the bucking goes away. If so, I'm gonna bet that there's a short somewhere there.
 

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I have a 2000 duratec that had a misfire issue w/ no codes too.
What I eventually did is replace the COP. Solved the problem.
I'm going out on limb here but I beleive this 2000 MY with the redesign and COP had a heat management issue that shows up infrequently.
Now take the EDPM rubber used on the COP and electrical stress and add heat and the rubber begins to breakdown allowing leakage to occurr.
Mine only misfired when warm/hot.
The heat and electrical stress could effect any sheathed wire/cable too. Check for other frayed wire jackets.
just my $.02
 

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My 01 taurus has similar symptoms, but mine only bucks when i first take off when the engine is cold. I checked the code and it was a P0401 code. Where exactly is the DPFE sensor located? I ordered one tonight from carquest for 29 bucks luckily i get a discount since i work in a honda parts department lol. Any help will be appreciated
 
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