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This is my 2nd or 3rd time posting about my sisters 95 Contour SE 2.5L, but today is the day that I will be buying the part(either the EGR valve or the DPFE), and NEED to know ASAP which one to change...my sister doesn't have enough money to risk buying one part, only to have it turn out to be the other.
Just to refresh your memories.
Her car sputters, stalls, hesitates etc.
The ONLY code I've ever been able to get is 327 which means that the DPFE sensor is reporting a voltage that is below the self-test minimum of "0.2 volts".
I've tried cleaning her EGR valve with a spray can of TB cleaner and it usually stops the stalling for a few days.
But here's the reason I think I can basically eliminate the possibility of it being the DPFE. I disconnected the vacuum hose that connects to the top of the EGR valve, and it made absolutely NO difference at all. Now, to my understanding, a faulty DPFE would cause an over-active EGR valve because it would be supplying vacuum to the valve a lot more than it's supposed to. Well, if this is the case, than disconnecting the EGRs vacuum supply should have made the problem go away, right??
Tonight I'm going to try and connect a vacuum hose and suck/breath-in to see if the engine stalls. I think this will tell me if the EGR valve is moving or not, right?
I just don't understand why I'm getting the 327 code and not the code for too much EGR flow or something else. To me, a 327 can only be electrical, and not the valve itself...
I get confused just talking it!!!
Anyone?
THANKS!:)
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Joined: Aug 2002
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You probably can't suck hard enough to operate the EGR (There is a joke in there, I'm sure). Either use a handheld vacuum pump or T into another vacuum source. If the EGR opens on idle, it should run rough and/or stall.
My name is Richard. I was a Contouraholic.
NOW: '02 Mazda B3000 Dual Sport, Black
BEFORE: '99 Contour SE Sport
Duratec ATX Spruce Green
PIAA 510's, Foglight MOD, K&N Drop-in
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If it's the original DPFE I wouldn't hestitate getting a new one. Not the easiest to put on since it's buried up against the block under some tubing & such.
"Fear is the little death."
Muadib.
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Is there anyway to tell if it's still the original one?
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I'd change the DPFE first.
96 Sport 2.0L - 190,XXX miles
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Quote:
I'd change the DPFE first.
But WHY!!!!!!????
No one is answering my main question here:
How the hell could it STILL point to the DPFE if the problems persist when I disconnect the EGR's vacuum supply!???? Once I disonnect the EGR's vacuum hose, the DPFE is doing NOTHING to control the EGR valve anymore.
The only way that I see a DPFE sensor being able to make an engine stall all the time is by constantly sending the wrong signal back to the PCM, and therefore having the PCM activate the EVR and apply vacuum to the valve, which in turn will open the valve when it's NOT supposed to, and voila, stall.
If I'm wrong here...some one please tell me why and explain further...
THANKS:)
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Originally posted by Contouraholic:
You probably can't suck hard enough to operate the EGR
Of course you can. It takes less effort that does drinking a milkshake through a straw.
5.1:
The 327 IS an electrical problem. You are close to the right track, but you have a slight misunderstanding of how the EGR system works.
In a nutshell, here is how it is supposed to work:
1. PCM tells EVR (EGR Vacuum Regulator) solenoid to open, applying manifold vacuum (restricted) to the EGR valve.
2. EGR valve opens, allows exhaust gas to pass through air tube, EGR valve, and intake.
3. The exhaust gasses pass by an orifice in the air tube enroute to the EGR valve. There are sample tubes connected to the air tube on each side of the orifice. When there is EGR flow, there is a difference in pressure/vacuum between the two sides of the orifice.
4. These tubes are connected to the two inputs of the DPFE ( DIFFERENTIAL Pressure Feedback EGR) sensor. The DPFE sensor outputs an analog voltage that is proportional to the difference in pressure/vacuum between the two sample tubes. This voltage is fed back to the PCM as an input to tell the PCM how much EGR flow is taking place.
5. The PCM can, under its programming, vary the duty cycle to the EVR solenoid, which varies the EGR flow rate which is reported back to the PCM by the DPFE sensor.
Basic closed loop feedback control system.
Now to your 327 code:
This indicates that the output voltage of the DPFE is below the lower limit of 0.2 V when there is no EGR flow (lower limit is around 0.45 V).
There is a simple test to see whether the fault is due to the DPFE sensor or an external fault, however, the physical location of the DPFE sensor and its connector on the 2.5L makes it a challenge to perform.
1. Key off. Disconnect the connector from the DPFE sensor. Jumper the Vref wire in the wiring connector to the DPFE circuit (consult your schematics for exact wire color codes for your year/model - I can't read the wire color codes on my service CD drawing) on the wire harness connector.
2. Re-run the KOER test and watch what codes are output.
3. a: No codes generated - wiring harness or PCM fault
b: 337 code - DPFE sensor bad
c: 327 code again - check Vref circuit to the DPFE sensor for an open circuit (loss of Vref to the DPFE sensor)
There you go - the tools to DIAGNOSE the 327 code you are encountering. Good luck.
FWIW, my bet is that after you fix the 327 problem, you will still have at least one additional problem code that will then crop up. Unfortunately, you will have to fix this problem first.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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Thanks Steve,
But, if you go by the way that you describe the EGR system, which I believe to be correct, than the DPFE sensor can have absolutely NO effect on how an engine runs.
Why? Because all your saying is that the DPFE tells the PCM how much EGR flow there is, but you're not saying that this information actually CONTROLS EGR flow. So if all the DPFE sensor does is tell the PCM how much EGR is flowing, how can a bad DPFE sensor cause an engine to stall??? If the DPFE is simply a feedback sensor, and the PCM does nothing based on this info, a bad DPFE would cause nothing other than a DTC.
I also go back to my original question: If the vacuum supply to the EGR valve is disconnected, and the problems persist, than how can the problem possibly be an EVR or DPFE problem? To me, a DPFE reading low would cause the PCM to command too much EGR flow(because it thinks not enough is occuring), and as a result, there would be constant vacuum going to the EGR valve. BUT, disconnecting the valves vacuum supply SHOULD quickly reveal whether this is the case or not...correct?
THANKS MAN!:)
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The DPFE does not directly control anything on the engine. Only the PCM does that. Normally, there is NO EGR flow at idle or at WOT. It is entirely up to the programming within the PCM as to whether or not EGR flow is commanded based on the operating parameters built in to it.
As to your repeated question, please refer to my last comment above regarding multiple problems.
You will have to clear the reason for the 327 before you can intelligently proceed further.
I suspect your DPFE is defective, but you also have an additional problem, perhaps caused by the extended period of time that the condition causing the 327 has been there. Possibilites include a stuck open EGR valve, faulty IAC, or some other intake vacuum leak.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
ANY THREAD WITH "OMG" or "WTF" ETC IN THE TITLE WILL BE IGNORED!
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Quote:
I suspect your DPFE is defective, but you also have an additional problem, perhaps caused by the extended period of time that the condition causing the 327 has been there.
This is actually exactly what I was thinking. I thought that perhaps the EGR valve keeps getting stuck open because after I clean it all up, the DPFE will than cause an over active vacuum supply...resulting in extra carbon build-up etc.
?
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