Misfire??

pryornfld · #1 11-07-2005, 08:47 AM

I recenly posted about having the P401/P402 codes and it was mentioned about the DFPE(I think) sensor as the problem. I haven't had the chance to change it out, but this weekend my fan started up very rough, the check engine light flashed( indicating a misfire) then back to solid. Only done it while starting, but never while driving.

Any ideas or tips out there??

busboy4 · #2 11-07-2005, 09:12 AM

Quote:

Originally Posted by pryornfld

I recenly posted about having the P401/P402 codes and it was mentioned about the DFPE(I think) sensor as the problem. I haven't had the chance to change it out, but this weekend my fan started up very rough, the check engine light flashed( indicating a misfire) then back to solid. Only done it while starting, but never while driving.

Any ideas or tips out there??

HI
I don't want to minimize what could be a larger problem, but I have occasionally had the same problem: van runs fine, then suddenly on a given start up it shudders, idles very poorly and CE light comes on. Every time, I have shut it off, waited a few seconds and then re-started with no problem. CE light has stayed on, and it has been a cylinder 1 mis-fire. I have cleared it and moved on with no further problems. This has happened probably 3 times in 2 years. I have changed my DPFE based on CE light codes.

pryornfld · #3 11-07-2005, 03:02 PM

Would the DFPE sensor cause both an EGR flow problem as well as a misfire?

DRW1000 · #4 11-07-2005, 03:46 PM

Quote:

Originally Posted by pryornfld

Would the DFPE sensor cause both an EGR flow problem as well as a misfire?

The DPFE only measures the flow through the EGR system. If the sensor was indicating a low flow the PCM may try to increse the flow by opening the valve for longer durations. If there was more EGR flow than required and/or some of the EGR ports were clogged you could get misfores. At idle however, there should be no flow. If the code indicates that the EGR is open at idle (which it should not be) then this could cause misfires.

pryornfld · #5 11-07-2005, 04:01 PM

My first CEL came on I had it read. It came back with both P401/P402,which to me sounds like the sensor.How difficult and how long of a procedure would it be to clean the egr ports? Is there some additive I could use to pre-treat the ports before I begin to take it apart.?

MT-2500 · #6 11-07-2005, 04:08 PM

Clear codes and unplug EGR valve.
If no missfire with egr unpluged it is time to clean egr valve ports.
What engine and what mileage?
MT-2500

pryornfld · #7 11-08-2005, 06:59 AM

My engine is a 96 3.8L with 190K. I had the egr ports cleaned about 4 years ago. How difficult would it be to clean the ports? I'm not much of a mechanic, so if it is a timely job, probably bring it in to get done.

pryornfld · #8 11-08-2005, 09:02 AM

Anyone have a step by step procedure on how to clean the EGR ports?

MT-2500 · #9 11-08-2005, 09:25 AM

Have you run the egr valve unplug test to see if that is the problem?
MT-2500

pryornfld · #10 11-08-2005, 10:27 AM

Not yet. What should I see when I unplug the EGR valve? COuld it just be the injectors that need cleaning as well?

DRW1000 · #11 11-08-2005, 11:00 AM

unplugging the EGR vacuum line will eliminate EGR flow. (unless the EGR is mechnically stuck open.

This will eliminate problems caused by:
1-Clogged EGR ports that force too much EGR flow to one or two cylinders.
2- EGR operation at low RPMS when it should be closed.

pryornfld · #12 11-08-2005, 11:21 AM

Quote:

Originally Posted by DRW1000

unplugging the EGR vacuum line will eliminate EGR flow. (unless the EGR is mechnically stuck open.

This will eliminate problems caused by:
1-Clogged EGR ports that force too much EGR flow to one or two cylinders.
2- EGR operation at low RPMS when it should be closed.

So what you are saying is: If the EGG Ports are clogged,by removing the EGR lines I shouldn't get any misfire. If there is still a misfire, then what would be my next logical step to take?

DRW1000 · #13 11-08-2005, 01:03 PM

Quote:

Originally Posted by pryornfld

So what you are saying is: If the EGG Ports are clogged,by removing the EGR lines I shouldn't get any misfire. If there is still a misfire, then what would be my next logical step to take?

Almost.....If you disable the EGR then you should not get any misfires due to clogged EGR ports. However the EGR could be mechanically stuck open. Disabling will not stop the flow in this instance.
A stuck open EGR should trip the CEL though. One additional note is that disabling the EGR should flag a code too since the DPFE will not detect flow when there should be some.

pryornfld · #14 11-08-2005, 03:41 PM

Quote:

Originally Posted by DRW1000

Almost.....If you disable the EGR then you should not get any misfires due to clogged EGR ports. However the EGR could be mechanically stuck open. Disabling will not stop the flow in this instance.
A stuck open EGR should trip the CEL though. One additional note is that disabling the EGR should flag a code too since the DPFE will not detect flow when there should be some.

Since prior to this event I had codes P401/402, which I think may be the DPFE , could this also cause a problem. How would I check this?

DRW1000 · #15 11-08-2005, 04:17 PM

Quote:

Originally Posted by pryornfld

Since prior to this event I had codes P401/402, which I think may be the DPFE , could this also cause a problem. How would I check this?

a while ago I posted step by steps for testing the DPFE. Try a search under DPFE.

If your DPFE is a silver metallic case then chances are it has gone bad. It has been re-designed.

Not sure of what year Windstar you have but I noticed you are an electronics guy so this may be of interest. I drilled out the 6 rivets on my DPFE and noticed that there was a discontinuity between one of the the pins on the outside and the circuit card. I was able to re-attach and then to reassemble and my DPFE has been working for well over a year since then.

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