DPFE Sensor

[lastexit99]

A little background...

I have been trying to identify two problems for a while. One being my horrible fuel mileage, the other being a check engine light that refuses to go out. I have had the car to my local Ford garage and the CEL is the "Evaporative Emissions" code. I replaced everything they told me could be causing the CEL, but it persisted. So I was talking to a parts guy about these issues last night and he said that the CEL could be caused by the DPFE sensor, He went on to say that the mid 90's era were notoriously bad for this particular part.

What do you think? $50.00 for the part, looks very simple to install...anyone wanna bet if it will fix either of my problems?

 

[iamtheshaner]

Need the code and a list of everything you replaced.

DPFE is basically an EGR flow sensor and has nothing to do with evaporative emissions.

I bet you $100 you will waste $100 of your time and $200 of mine chucking $50 worth of parts at a car with $2 worth of diagnostics done to it!

 

[lastexit99]

ok then, what should I do, in your opinion? I have taken it to a garage, had the code read, told them to run tests on it. They said they did, and they couldn't find anything wrong that was causing the code.

 

[MustangMatt77]

If you want to perm. Fix the CEL, remove the bulb............. Just kidding.
To check your sensor if you want to:

Remove the 2 rubber hoses from the bottom of the sensor. Attach a piece of rubber hose to the forward most hole in the sensor. Now carefully take a small safety pin and stick it in behind the top wire parallel to the wire. You do NOT want to pierce the wire, only make contact inside the connector. This top wire is the active feedback signal wire. It will vary from 0-5 volts or so. The middle wire is ground. The bottom wire is 5-6 volts supply. Now the top wire voltage will vary as the pressure between the two holes in the sensor varies. Set your meter to read volts, either turn the key until the accessories are on or start the engine, either way is fine. Now using your mouth apply suction to the hose and you will see the voltage change from near 0 to near 5 if you apply enough suction. The vacuum on the hose should hold your tongue and not leak. If the voltage does not vary or is stuck high or low, the sensor is bad. Do the same thing to the rear port but the voltage difference will be much less, this is the reference port.
If the sensor seems to be working then you can further test the system by doing the following. Attach the hoses to the sensor as normal. Now remove the rubber vacuum hose from the top of the EGR valve diaphragm. With the engine running apply slight vacuum to the EGR valve and this will open the EGR valve. When the valve opens you will see the voltage on the top wire of the DPFE sensor change indicating flow. When the vacuum is applied your car should stumble or almost stall indicating the EGR valve has opened which it normally does not do at idle. I hope this helps.

 

[96COBRACONV1]

If you still have the big square alluminum dpfe sensor next to you egr valve it is most likely bad because the replacement ones for ten years have been plastic and it pobably original. That will not cause a weird emission code. Usually the code for dpfe is improper flow/voltage to egr regulator. Your problem is most likely in your big,complicated,stupid secondary are injection garbage and a team of engineers from ford would spend ten grand trying to get that light out. Do what the other guy said do and pull the bulb!. It doesnt hurt anything and it is not liklely related to you poor fuel milage.

 

[racecougar]

Need the code and a list of everything you replaced.

DPFE is basically an EGR flow sensor and has nothing to do with evaporative emissions.

I bet you $100 you will waste $100 of your time and $200 of mine chucking $50 worth of parts at a car with $2 worth of diagnostics done to it!

Agreed.

ok then, what should I do, in your opinion?

Provide us with the actual code number, along with a list of the parts you replaced.

 

[lastexit99]

Code I am getting is P1443. The parts I have replaced are the evap canister, the solenoid, the valve, and all the hose between them.

 

[racecougar]

Have you checked the wiring? Specifically at the evap purge solenoid? One wire in the connector will have 12V at key on. The other wire will supply ground when commanded by the EEC. To check that wire, bring the engine up to operating temp, then open the throttle to increase your rpm to ~1500, and you should see -12V.

 

[lastexit99]

If you still have the big square alluminum dpfe sensor next to you egr valve it is most likely bad because the replacement ones for ten years have been plastic and it pobably original. That will not cause a weird emission code. Usually the code for dpfe is improper flow/voltage to egr regulator. Your problem is most likely in your big,complicated,stupid secondary are injection garbage and a team of engineers from ford would spend ten grand trying to get that light out. Do what the other guy said do and pull the bulb!. It doesnt hurt anything and it is not liklely related to you poor fuel milage.

mine is the original aluminum piece, and has not been replaced.

 

[iamtheshaner]

Forget about your DPFE sensor - it has nothing to do with your P1443.

This is a weird year for EVAP stuff because Ford used a few different types of purge systems. I've looked through the factory emissions manual for a 96 Mustang.....

First: When you say you replaced the canister, solenoid, valve and all the hoses.... What valve did you replace? Aside from your rollover valve, the only other "valve" is a solenoid valve and it is what the PCM uses to allow the engine to draw fuel vapors from the tank to the intake manifold. I'm just curious what you mean by "solenoid" and "valve"...

I know EVAP system operation and diagnostics very well but I don't know if your Cobra is a system with a purge and vent valve / FTP sensor combo or one of the goofy purge flow sensor setups with no canister vent.

If you have the purge flow sensor (3 wire sensor spliced into the line between the intake and the 2 wire purge valve) this P1443 code means the PF sensor isn't changing when the PCM commands the purge valve open. From what I understand the PF sensor is similar to a fuel tank pressure sensor. According to the book there are two types of PF sensors: one which has a 1v resting signal and another which has a 2.5v resting signal.

I can copy the diagnosic chart if you'd like.....

Based on what you've said I'm guessing you have resistance in the wiring to the purge valve or an issue with the PF sensor or it's associated wiring. Likely not an open or a short because you'd be setting a circuit code as well.

Depending on how technical you are and what equipment you have available - it shouldn't be too hard to figure out.

Either way whatever shop you took it to isn't very well informed.....

 

[lastexit99]

http://www.svtperformance.com/forums/showthread.php?591039-P1443-How-To-Fix

If you look at this post you will see the canister, valve, & solenoid I replaced. The set up described in that post is the same that is on my Cobra. Last night I used my code reader to clear the code. I ran the car for about ten minutes, plus took it for a quick drive. The light never came back on. I didn't get to drive it to work today because hauling 2 kids in that car is not ideal. I will drive it some more this weekend and see what happens.

 

[lastexit99]

CEL came back on yesterday (Friday). I have a busy weekend, but I will try to get the wiring you mentioned tested. I'll post back with results.

 

[SVT CAMR]

I have just recently installed my DPFE sensor back onto the car. I currently have the 2 lines that come out of the DPFE capped. I also have my EGR capped off where the hard line would have went down to the exhaust.

I was looking at that hard line that is up in the attic and there are 2 short rubber hoses that come off that line.

My question is did these 2 rubber hoses go to the DPFE?

 

[SVT CAMR]

Have you checked the wiring? Specifically at the evap purge solenoid? One wire in the connector will have 12V at key on. The other wire will supply ground when commanded by the EEC. To check that wire, bring the engine up to operating temp, then open the throttle to increase your rpm to ~1500, and you should see -12V.

I'm curious where is this evap purger solenoid located?

 

[racecougar]

I have just recently installed my DPFE sensor back onto the car. I currently have the 2 lines that come out of the DPFE capped. I also have my EGR capped off where the hard line would have went down to the exhaust.

I was looking at that hard line that is up in the attic and there are 2 short rubber hoses that come off that line.

My question is did these 2 rubber hoses go to the DPFE?

Yes.

 

[mwolson]

I'm curious where is this evap purger solenoid located?

Passenger side on a vacuum line going into the fender.

A lot of times a smoke test can find a leak that can cause this DTC. That was the case with my car years ago.

 

[SVT CAMR]

Passenger side on a vacuum line going into the fender.

A lot of times a smoke test can find a leak that can cause this DTC. That was the case with my car years ago.

Thanks guys.

Mark is that the one with the hose that has a red stripe?

I'm just wondering for general knowledge for the future.

 

[mwolson]

It's the gizmo with the blue connector in the upper left hand corner of this picture and yes, the hose with the red stripe:

 

[SVT CAMR]

It's the gizmo with the blue connector in the upper left hand corner of this picture and yes, the hose with the red stripe:

Thanks!
Of course the 98 looks a little bit different. Lol but basically the same.