98 3.0 Emmisions codes and Stalling

[goser]

98 Ford Windstar 3.0

On a short trip yesterday stalled four times at idle and at speed.

Pulled Codes P0401 and P0430.

For Stalling:
Tried to test fuel pressure but adaptor was too long to fit...
Tried to test battery but can't find multimeter...

Read around forums...EGR code sounds like DFPE problem. Could this be causing stalling?

I haven't been able to test DFPE yet, but I could pull a known working one off a 3.8...anyone know if they're interchangeable?

For the P0430 the oxygen sensor seems to be switching fine... would this indicate a bad catalytic converter then?


Thanks!

[wiswind]

For the P0401 code, Insufficient EGR flow.
One test that you can do to see if the rough running is caused by the EGR system is to remove and plug the vaccum line that goes to the top of the EGR valve.
Now....this WILL cause the CEL to come on for insufficient EGR flow....as you have disabled the EGR system (unless the EGR valve is stuck, which is not common on the windstar).
Take the vehicle for a drive, and see if the stalling problem is resolved.
If there is no change, then the stalling is not caused by the EGR system (with the exception of the stuck EGR valve possibility, which is not likely).
If the stalling problem is NOT present, then the problem is caused by the EGR system.

In either case, reconnect the vaccum line to the EGR valve.

The EGR system should NOT be open at idle.
It should open under driving conditions, in an amount that is regulated by the PCM based upon the feedback from the DPFE.
The PCM regulates the opening of the EGR valve by sending an electrical signal to the EGR vaccum modulator solenoid, which is where the other end of the vaccum line, that connects to the top of the EGR valve, connects to.
Little to no vaccum results in the EGR valve being closed.
Vaccum causes the EGR valve to open.

One common cause of rough running when the EGR system is open, is clogged EGR ports in the lower intake manifold.
You have to remove the upper intake manifold to get to the EGR ports to clean them.
No fuel additive or spray into the intake will clean them.

So, in short, the MOST common causes for the P0401 is the DPFE or dirty EGR ports.

I show the EGR ports in my pictures, that the link in my signature takes you to.

P0430, Catylist Efficiency Below Threshold, Bank #2.
This is an indication by the oxygen sensor that the catalytic converter for bank #2 cylinders, is not working properly.
Bank #2 is the front bank of cylinders.
It is possible that the problem that is causing the stalling is related to the catalyst not working correctly.
So, I would correct any problems with the EGR system, if your checking comes up with something there.


It is interesting to note, that the EGR pipe is connected to the exhaust manifold for the FRONT bank of cylinders, which is the same bank that the catylist code is for.
I would check to see if the EGR pipe is intact (although I would expect that it would be REALLY loud if it were not) and that the exhaust system is intact.
This involves an under vehicle inspection.
I know that the rear most converter on my '96 3.8L had the downstream oxygen sensor mounted into the rear part of the catalytic converter, instead of into the pipe.
When I was changing my "Y" pipe, which includes both converters, the oxygen sensor that was mounted into the rear most converter broke right out of the converter, when I tried to remove the sensor.....with very little turning only pressure.
So, if something like that happened, understandably, the sensor would not be reading the correct value......from outside the converter.
Leaking exhaust, broken or pinched exhaust parts could all cause an issue.


Has any work been done recently on the vehicle?
If the wires for the oxygen sensors have been connected to the wrong sensors....you could be getting some strange codes.
This is mentioned in my AldataDIY information for this code.....and comes up a few times here and there elsewhere.

After the EGR system has been verified/corrected.
One could switch the downstream oxygen sensors between banks.
However, if one of those sensors is mounted into the body of the catalytic converter, I would NOT try to remove it unless I had to......for the reason that I stated above.

Replacement of the catalytic converters with genuine OEM is expensive.
Both converters are part of the "Y" pipe assembly.
List price for the one for my '96 is about $1600.
I found it for about $1200 from one of the online genuine Ford part places.
I got a Walker "direct fit" aftermarket replacement several years ago for about $321 through Rock Auto.

For this reason, I would want to be fairly certain that my catalytic converter is really defective before replacing it.

[goser]

Wow. Thanks!

[goser]

I removed the vacuum line and plugged it and went for a drive. Stalling problem is still present. Oddly no DTC was registered though.

Was able to check fuel pressure by removing alternator. Key on engine off was 30. Thought that was a little low so key off then on...35. Odd. Key off then on again...33. So I'm starting to suspect fuel pressure. Obviously can't drive without alternator...does anyone know if a scanner would read fuel pressure as I drive?

[garync1]

Originally Posted by goser

I removed the vacuum line and plugged it and went for a drive. Stalling problem is still present. Oddly no DTC was registered though.

Was able to check fuel pressure by removing alternator. Key on engine off was 30. Thought that was a little low so key off then on...35. Odd. Key off then on again...33. So I'm starting to suspect fuel pressure. Obviously can't drive without alternator...does anyone know if a scanner would read fuel pressure as I drive?

My scan gauge will on some fords but my 2001 does not have it on its PCM but my nephews 2003 Ford ZX2 does so if you know some one with one you can try it..Also if you want to use the The fuel pressure gauge and keep the alt off just have someone to get in van put in drive with foot on brake to get a good load up that should work fine. Pressure range is key off 35-45 psi vac hose connected 28-45psi. disconnected 38-50 psi.. five minute hold pressure 30-40 psi ... same for both 3.0 and 3.8 maybe where the wide range comes in..

[wiswind]

You will NOT be able to read fuel pressure with a scan gauge on your Windstar.
As Gary mentioned, it is in the capability of some readers, like our Scan Gauge, however the Windstar does not measure or monitor the fuel pressure.
There is NO measurement of fuel pressure or fuel flow.....on the Windstar.

The reason that I am over stating this is that, not only will you not be able to monitor the fuel pressure from the OBDII port, the PCM has no idea of the fuel pressure or fuel flow, so there will be NO CEL with a code that indicates "Low fuel pressure" or "Low fuel flow".


You will have maximum values, as Gary mentioned, with NO vaccum to the fuel pressure regulator.
This is because the fuel pressure regulator maintains higher fuel pressure under higher engine loads......at which time the vaccum is low.
Intake vaccum is highest under no load conditions, which requires less fuel, so the pressure regulator reduces the fuel pressure in the fuel rail.

This problem is sounding JUST like a recent member had posted.....and they found that the fuel pump was weak.....and replacement of the fuel pump solved the problem.
FIRST, make sure that you have a good fuel filter, and not an old clogged one that is restricting fuel flow.

There is also (in addition to the filter that is under the vehicle, near the back, driver's side tire) a "sock" filter on the fuel pump's pickup arm.
But then.......if that were clogged, you might as well replace the fuel pump....as you have to drop the gasoline tank and remove the fuel pump to get to that.

[goser]

Thanks for the help.

Replaced DPFE and fuel filter and it seems to be running fine now. The catalyst code never reappeared so I'm not worrying about it right now.

I did determine that the DPFE is the same for the 3.0 and 3.8, though I wound up replacing it with one off a 3.0. Oddly, neither the old or new sensor passed KOEO test I found here: http://rockledge.home.comcast.net/~r...tage-Test.html but maybe I was just doing it wrong.

[goser]

Looks like I spoke too soon, stalling continues. On to the fuel pump or off to the wreckers...