1995 Mustang-DPFE sensor voltage - Ford Mustang Forum
 
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post #1 of 6 (permalink) Old 10-11-2010 Thread Starter
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1995 Mustang-DPFE sensor voltage

another problem,I went to autozone today and had them pull my CEL codes. It is pulling up a P1400 and a P0171 which the 1400 is a DPFE Circuit Low Voltage Detected.

The P0171 is a Lean condition.



now I was checking the voltage out of the DPFE power connecter and it is as follows:


With the neg test lead on the ground (a bolt on the frame):

Black and White wire: 5.03v

Black only: 1.38v

Judging from this I'm assuming that the red and grey wire is Ground? I'm kinda lost.

anyone have suggestions?

I just wanted to make sure I'm getting the correct voltage out of the wiring harness before I shell out the $50 to get a new DPFE sensor....
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post #2 of 6 (permalink) Old 10-11-2010 Thread Starter
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I forgot to add that I also tested the ground from the grey/red wire and my voltage is as follows:

Black and White wire:4.97v

Black:1.36v
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post #3 of 6 (permalink) Old 10-11-2010
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Troubleshooting DPFE values check vacuum lines

Disclaimer. I do not have a set of service manuals for the 95 MY. So, there is a little bit of "faith" going on here. The 2002 reference has the DPFE hot idle values as .95-1.05. So at 1.38 it is slightly out of this range.

Here's my take. DOUBLE CHECK the vacuum lines to/from the DPFE sensor. The exhaust gas is hard on rubber parts. The lines will dry up and leak. When they do, an exhaust leak is the result. More importantly, the DPFE will read incorrectly.

Next there is a LEAN code. Is this from the same bank as the EGR tube is on? Consider that an exhaust leak will cause a lean code due to excessive air entering the exhaust and making the PCM "Think" the bank is lean.

SO....is it possible there is a bad vacuum line to/from the DPFE sensor that is causing BOTH problems?

Next just to be sure, CLEAN the electrical connector to the DPFE sensor. Use electrical contact cleaner (or MAF cleaner). Lightly grease the contacts with silcone di-electric grease (the same kind used for spark plug).

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2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #4 of 6 (permalink) Old 10-11-2010 Thread Starter
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Quote:
Originally Posted by wmburns View Post
Disclaimer. I do not have a set of service manuals for the 95 MY. So, there is a little bit of "faith" going on here. The 2002 reference has the DPFE hot idle values as .95-1.05. So at 1.38 it is slightly out of this range.

Here's my take. DOUBLE CHECK the vacuum lines to/from the DPFE sensor. The exhaust gas is hard on rubber parts. The lines will dry up and leak. When they do, an exhaust leak is the result. More importantly, the DPFE will read incorrectly.

Next there is a LEAN code. Is this from the same bank as the EGR tube is on? Consider that an exhaust leak will cause a lean code due to excessive air entering the exhaust and making the PCM "Think" the bank is lean.

SO....is it possible there is a bad vacuum line to/from the DPFE sensor that is causing BOTH problems?

Next just to be sure, CLEAN the electrical connector to the DPFE sensor. Use electrical contact cleaner (or MAF cleaner). Lightly grease the contacts with silcone di-electric grease (the same kind used for spark plug).

Thank you for your feedback. I'll double check the lines tomorrow when I get back from my job interview but just from a visual standpoint they look like they are fine.

As for the lean code, I'm assuming that its on the passenger side of the engine as I've been having issues with a lean mixture since I've had the car, so needless to say I've had poor gas mileage since I've had it (since January 2010) I'm trying to get this problem fixed so my car isnt sucking down gas like its water. I'm also planning on seafoaming it and seeing if that will also help with gas mileage.


as for the rest of the engine, for it being a 1995 it runs great, I've had no other problems out of it other than this and my overheating problem which I do believe I have fixed.
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post #5 of 6 (permalink) Old 10-11-2010
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Are there ANY exhaust leaks anywhere on the car?

Remember that an exhaust leak will make the PCM think it is lean. But is it not lean. This causes a chronic RICH condition as the PCM attempts to adjust for the false condition.

2003 GT Convertible (sold & missed)
2000 GT coupe (Craigslist project. Fixed. Now my DD). Windsor to Romeo swap.
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post #6 of 6 (permalink) Old 10-11-2010 Thread Starter
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There was at one time, which was a loose bolt at the header flange. I just recently tightened it, I might have to tighten it again. when I get some money I'm gonna take it to an muffler shop and have them look at it and see if there are any leaks. but as far as I know I dont think I have anymore.
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