Melted DPFE sensor - and P701

[Pulse97]

Aloha everyone!
:exp:Anyone have experience with a melted DPFE sensor? I'm working a bunch of issues at the same time:
- extremely rough idle and loss of power
- replaced cats - still sounds like rocks in the muffler
- replaced upper/lower intake gaskets (torqued lower to 10ft pds
- replaced thermostat housing
- cleaned MAF sensor and throttle body
- still throwing a P171 code. I sprayed carb cleaner around the intakes - no change in idle, so I think my intake gaskets are good.

I'm worried about the melted sensor - I spotted exhaust coming straight out of the vacuum tubes that connect to the sensor - is that normal?

Anyone have any advice?

 

[koda2000]

Have you considered replacing your EGR valve? Melted DPFE's are not uncommon. I would think a bad or clogged EGR valve might cause this (and other problems) as it might let hot exhaust gases to get into the DPFE through it's vacuum line and not open to do it's job.

 

[Pulse97]

Have not swapped the EGR valve yet, but that sounds like a reasonable plan. Thanks for the suggestion!

 

[1998Exp]

Older DPFEs are sure prone to damage from the hot, corrosive exhaust hooked to them, but as far as I know they have no no vacuum connection. The vacuum connection is between the EGR valve and the solenoid/regulator.

Have you considered replacing your EGR valve? Melted DPFE's are not uncommon. I would think a bad or clogged EGR valve might cause this (and other problems) as it might let hot exhaust gases to get into the DPFE through it's vacuum line and not open to do it's job.

 

[Pulse97]

Thanks 1998Exp- I saw a thread that said there shouldn't be exhaust gases flowing to the sensor. Anyone know for sure whether gas should be flowing to the DPFE?

 

[1998Exp]

The DPFE measures EGR flow by sensing the pressure at two two points along the EGR tube. Thus there is an exhaust connection to the EGR, but it's "dead head" -- the sensing tubes terminate at the DPFE, so hot exhaust gas reaches it but does not flow through it. Hope that makes sense...

Thanks 1998Exp- I saw a thread that said there shouldn't be exhaust gases flowing to the sensor. Anyone know for sure whether gas should be flowing to the DPFE?

 

[Pulse97]

Makes perfect sense. The question I have is "why did it burn up the sensor now?" Could it be related to my new catalytic converters? The dpfe was fine 2 weeks ago and I've hardly driven it.

 

[1998Exp]

Nothing to do with the cat converter, but I just noticed that you called the EGR sensing 'vacuum tubes'. These must special hi-temp material. If you used vacuum tubes there, they will melt in no time.

Makes perfect sense. The question I have is "why did it burn up the sensor now?" Could it be related to my new catalytic converters? The dpfe was fine 2 weeks ago and I've hardly driven it.

 

[Pulse97]

Good catch- I've got the right hoses- used the wrong words! Replaced the dpfe sensor. I'm going to focus on my vacuum leak issue, hopefully can get it solved. Thanks again!