Code 401

I have a 96 explorer 4.0 ohv with the check engine light on. A scan
indicates code 401, insufficient flow detected. Mechanic replaced egr
valve and cleared the code. CEL came pack on, code 401. I replaced the
DPFE sensor and both hoses. Blew through both hoses to make sure there
was no blockage and cleared the code. CEL came back on within 30 miles,
same code. HELP!! running out of ideas.
Jack

You need a better mechanic. The EGR system is simple to diagnose for anyone
with a handheld vacuum pump, a scanner, basic understanding how things work
and a manual.
Now that you replaced the valve and the DPFE (presumably it's not connected
backwards), we can assume that there is indeed insufficient flow and it is
not caused by a malfunctioning valve. Still quite a few options: bad
regulator (solenoid), no or low vacuum supply to the regulator, an
obstruction between the regulator and the valve, clogged EGR tube (at the
restriction point perhaps)... What should I say? You can keep throwing parts
at it, or try to diagnose it. Your choice
A very simple test to see that there is no major obstruction anywhere in the
EGR path is to let the engine idle and force the valve open with a vacuum
pump (or perhaps by smartly sneaking a tee into a vacuum line somewhere).
When the valve opens the engine should stall, or at least hesitate severely.

"jack" > wrote in message
. ..
>I have a 96 explorer 4.0 ohv with the check engine light on. A scan
>indicates code 401, insufficient flow detected. Mechanic replaced egr valve
>and cleared the code. CEL came pack on, code 401. I replaced the DPFE
>sensor and both hoses. Blew through both hoses to make sure there was no
>blockage and cleared the code. CEL came back on within 30 miles, same code.
>HELP!! running out of ideas.
> Jack

Happy Traveler wrote:
> You need a better mechanic. The EGR system is simple to diagnose for anyone
> with a handheld vacuum pump, a scanner, basic understanding how things work
> and a manual.
> Now that you replaced the valve and the DPFE (presumably it's not connected
> backwards), we can assume that there is indeed insufficient flow and it is
> not caused by a malfunctioning valve. Still quite a few options: bad
> regulator (solenoid), no or low vacuum supply to the regulator, an
> obstruction between the regulator and the valve, clogged EGR tube (at the
> restriction point perhaps)... What should I say? You can keep throwing parts
> at it, or try to diagnose it. Your choice
> A very simple test to see that there is no major obstruction anywhere in the
> EGR path is to let the engine idle and force the valve open with a vacuum
> pump (or perhaps by smartly sneaking a tee into a vacuum line somewhere).
> When the valve opens the engine should stall, or at least hesitate severely.
>
> "jack" > wrote in message
> . ..
>> I have a 96 explorer 4.0 ohv with the check engine light on. A scan
>> indicates code 401, insufficient flow detected. Mechanic replaced egr valve
>> and cleared the code. CEL came pack on, code 401. I replaced the DPFE
>> sensor and both hoses. Blew through both hoses to make sure there was no
>> blockage and cleared the code. CEL came back on within 30 miles, same code.
>> HELP!! running out of ideas.
>> Jack
>
>
Yep, new mechanic is on order!!(already figured that one out). Think i
found the problem about 2 min after the post. A disconnected vacuum line
to the egr valve.
Thanks,
Jack