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Discussion Starter · #1 · (Edited)
Hello everyone,

This is my first post, nice to find a site devoted to such a great car. Here is my story/conern/question.

I recently purchased a 2004 Taurus SE with the Vulcan motor w/ 191k on the clock. The car had been sitting for about a year when I picked it up. The previous owners stated that it needed some work to get it running right.

After I got it home I determined (by use of my sister-in-laws Taurus) that it needed a coil pack and a mass air flow sensor to get it running. Since the car was high mileage & had been sitting, heres what I did to get it running and to perform some PM:

1. New Coil Pack
2. Plugs & Wires
3. Air Filter
4. Mass Air Flow Sensor
5. Fuel Filter
6. New Trans Filter and Fluid
7. Oil Change w/ Filter
8. Tecron by Chevron Fuel Treatment
9. Rear Shoes & Drums

After all of the above were done, the car ran (and still does) run like a champ. The PO also had a short belt on it since the A/C Compressor locked up. So I also threw on a new compressor.

So the concern, everyonce in a while (at random intervals) while traveling mainly at steady around 60-65ish the car will surge a bit, or to better describe it, push forward and then pull right back. the tac moves up about 50-100 rpms when this happens.

At first I thought it was the transmisson throwing fits, so I changed the fluid again (knowing that I was not able to get everything out of the torque converter when I intially dropped the pan). My thought was the fluid was dirty/low. After the fluid change, the issue still presents itself.

I should aslo note that this issue recently started happening. I had been driving the car for several weeks with the short belt on it with no issues, since I just got the compressor replaced and the A/C charged.

On my way into work today, it dawned on me that the A/C compressor was the last thing that I did to the car that may be causing this issue as it cycles on and off. So I turned the HVAC off and there we no more surges, etc. Turned it back on and it immediately did it. Turning the A/C off and on, I was able to duplicate the issue on command.

So the real question, is there any fix for this annoying issue? I read in other threads that replacing the fuel filter may help, but I had already replaced it prior to the installation of the compressor. Anyone have any suggestions?

Thanks

Eric
 

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Your DPFE Sensor needs to be replaced, (Delta Pressure Feedback Egr) it's common among fords for this neat little sensor to fail and cause a freeway or cruising surge. Also keep in mind that the fuel has been sitting for a while and you may need to run a tank or two through there for everything to clear up.
 

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Discussion Starter · #3 ·
Outstanding, I'll throw a DPFE on it and see if I notice a change. Thanks for the advice! :)

As for the fuel, it had less than a half a tank in it when I bought it. And I have put over 2k miles on it so far, About 500 or so with the new compressor. So I've been through several tanks of gas.

Thanks again and Ill report back my findings.

Eric
 

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You should get a po401 code if dpfe is faulty. 3 things. I would get the battery load tested for free at a parts store or wallyworld. Next, i would contact ford (dealership) and have them check their oasis network for a pcm reflash recall. And lastly, i would look into replacing the cmp (camshaft position sensor) and camshaft synchronizer. Several other members have described your exact same symptoms with no accompanying po340 code. Problem is the cmp wont throw the po340 above 2500rpms. Might click on the search feature at the top of this page. If you do replace the dpfe, get the borg-warner one from advance auto or oreilly. Welcome and good luck.
 

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DPFE sensors have caused this issue on every model of ford that I have owned, the Ford Focus is HORRIBLE when they go bad and it didn't throw any codes. My taurus has a DPFE that was installed 28K ago and it was also exhibiting the same issues, If it is not the DPFE I will be surprised.
 

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The IAC is only active when the throttle is in the closed position. This is happening when the OP is cruising at highway speeds. Take a look at the TSB (Attached)
 

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The IAC is only active when the throttle is in the closed position. This is happening when the OP is cruising at highway speeds. Take a look at the TSB (Attached)
On the SHO the IAB controls both idle and while cruising. So unless it has changed on later Taurii it might be something worth checking.
 

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On the SHO the IAB controls both idle and while cruising. So unless it has changed on later Taurii it might be something worth checking.

While I agree with you, they didn't make a 2004 SHO (God knows they should have!) :lol2:
 

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Discussion Starter · #10 ·
So I finally got around to replacing the DPFE (after a scare with the check transmission light of death). When I removed the old one and there was moisture in the rubber hoses and if I hit the DPFE on a hard surface water came out. So I blew out the hoses and installed the new sensor. The initial road test yielded mix results, I still noticed it doing it, just as often as before.

Overnight I realized that I needed to reset the KAM so the PCM would relearn how to use the DPFE that was not filled with water. After leaving the battery disconnected for about 15 mins, I drove to work. Cruising along at 62mph, I did not notice it to being doing it at all. The ride home was less than satisfying. It did it maybe twice on my 25 minute drive, most of which was at cruising speed.

The interval at which it occurs has been greatly reduced by changing the DPFE and regardless the old one had water in it, so it needed replacing anyways. The old one had a Ford Motor Co. logo engraved on the back. Hard to believe that with 193k miles, that it was original.

I really think that the motor was changed on this car. When I changed the plugs and wires, they were all original. The plugs had the white painted tips. With 191k miles on original plugs, the car shouldn't have even started when I bought it!

I know there was mention about CMP Sensor, not throwing a code above 2500 RPMs. When I have the cruise set at 62, the tach reads a hair under 2200.

Any other ideas?, the check engine light is not on my MPG's are in the upper 26's. After replacing the DPFE, the number of times it happens has substantially reduced, making it tolerable but still mildly annoying.

Eric
 

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EGR system may be clogged with carbon build up creating the surge as well, you may want to check the EGR itself. CPS should not create the surge issue it would create a spark cut causing the vehicle to cut out above 3000 RPM so I don't think that it could be the cause. Though if it is the original cam position sensor I would be suprised!
 

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Discussion Starter · #12 ·
The more I drive it, the better it seems to be getting. Perhaps now that the system is operating as designed, it is working to clean itself out.

Over the past two days, it's only done it once. And at that rate, I'm happy. :)

Thanks for your help!

Eric
 

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I have a 2001 Sable, same engine - only 81k miles on it. Bought it used about 3 months ago. Exact same problem. Runs perfectly when AC is off. Get some surge/hesitation with AC on at steady speeds about 35-40 mph. It's almost as if the torque converter is trying to come out of lock up when the AC compressor clutch engages. It "hunts" for a couple of cycles over a span of a second or two before it settles back down to lock-up. Tach varies about 50-100 RPM while this is going on.

The solutions I've seen suggested here seem like they would apply to an engine issue that should occur with AC on or off. Wonder if it isn't more of a control system/transmission issue?
 

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Discussion Starter · #14 ·
I hate to revive an old post, but after having this issue for about a year and finally having the time, I replaced the lower and upper intake manifold gaskets as well as the EDR valve gasket and it IAC gasket. So far, the idle is rock solid at 750; and I've yet to notice the surge while cruising. Somewhere, there was a leak in the vac system sucking in un-metered air. Had a few lean codes along the way. Now there are no issues on a cold start up and at cruising speeds.

I should note that the EDR gasket was cracked on the back-side. The car seemed to run better when warm, or once the gaskets heated up and sealed any cracks.

I loved the car to much to give up easily and for the minuscule price of the intake gasket set, it was well worth tearing down to replace.
 

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Discussion Starter · #16 ·
Shelia I sure did. That was one of the first things I tried to resolve the issue. It was better for a day, then went right back into its old ways.
 

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I have a 2001 Sable, same engine - only 81k miles on it. Bought it used about 3 months ago. Exact same problem. Runs perfectly when AC is off. Get some surge/hesitation with AC on at steady speeds about 35-40 mph. It's almost as if the torque converter is trying to come out of lock up when the AC compressor clutch engages. It "hunts" for a couple of cycles over a span of a second or two before it settles back down to lock-up. Tach varies about 50-100 RPM while this is going on.

The solutions I've seen suggested here seem like they would apply to an engine issue that should occur with AC on or off. Wonder if it isn't more of a control system/transmission issue?
Finally got around to having the trans fluid changed. Fixed the problem completely. Comes out of, and goes into torque converter lock up smoothly under all conditions. The reason it seems to be related to the AC is that the torque converter unlocks for a split second every time the AC compressor clutch engages.
 

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2002 Taurus SE Vulcan 3.0

Mine has the same surge with the AC on. Seems less with the AC off.

New fuel filter, plugs and wires, new IAC, new differential pressure sensor, new camshaft synchro but not the sensor, cleaned the MAF.

The trans fluid looks good and it correct level. I just bought it about a month ago so not sure when the trans fluid was changed last.

Could the cam shaft position sensor be the cause of my surge? Should I change the tranny fluid?

My car is not throwing any codes and other than the surge it starts and runs fine.
 
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