code p0401 possible vacuum leak?help jeff laws et all!!
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01-23-2003, 03:22 PM
Join Date: Jan 2003
Location: mississippi
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code p0401 possible vacuum leak?help jeff laws et all!!
Here's the story
I had a minor wreck that messed up my front bumper and grill <but not radiator or fenders/hood>. I was able to drive my truck home, '97 f150 4.6L with 68,000 miles, and after about 30 miles the cil came on. I had the truck repaired by the body shop and the guy doing body work said that the light was probably on because the airbag went off. OK...i got the truck back with no cil on <pcm reset by body shop to reset airbag> after driving about 40 miles the cil came back on. Autozone said error code P0401. I looked at this site and studied up on P0401 from jeff laws , kyfreak et al and did some troubleshooting. Here is what I have done thus far.
1) took off throttle body and cleaned 90% clogged egr elbow and replaced with new gasket.
2) applied 8hg vacuum to top of egr valve and engine stumbled and almost stalled, but recovered. took off egr valve and carefully cleaned and it held 5 hg vacuum for 5 mins ok.also took off the tube that connects egr to manifold and cleaned with carb cleaner real good and blew out with air hose.replaced egr with new gasket.
3)reset pcm and after 70 miles or so same mil p0401.
4)resistance at EVR solenoid is 31 ohms
5)checked ref voltage at 5.75V and sig voltage on DPFE. showing .7 volts KOEO and placed vacuum to top of egr with KOER and monitored voltage at DPFE with vacuum applied. varried from roughly 1.7v to 3.6v. depending on vacuum applied.i went ahead and replaced DPFE as a probable cause.
6) reset pcm and 70 miles later code is back
Now.....i checked all vacuum hoses and the seem ok but i have a question... am i suppose to have a constant vacuum on the EVR solenoid? Meaning the white vacuum hose from the vresser to the bottom hold of the EVR? the top hose is going to top of EGR of course. I am sorry for the long post, but I wanted to include everything so as to get the entire background. Thanks folks!
I had a minor wreck that messed up my front bumper and grill <but not radiator or fenders/hood>. I was able to drive my truck home, '97 f150 4.6L with 68,000 miles, and after about 30 miles the cil came on. I had the truck repaired by the body shop and the guy doing body work said that the light was probably on because the airbag went off. OK...i got the truck back with no cil on <pcm reset by body shop to reset airbag> after driving about 40 miles the cil came back on. Autozone said error code P0401. I looked at this site and studied up on P0401 from jeff laws , kyfreak et al and did some troubleshooting. Here is what I have done thus far.
1) took off throttle body and cleaned 90% clogged egr elbow and replaced with new gasket.
2) applied 8hg vacuum to top of egr valve and engine stumbled and almost stalled, but recovered. took off egr valve and carefully cleaned and it held 5 hg vacuum for 5 mins ok.also took off the tube that connects egr to manifold and cleaned with carb cleaner real good and blew out with air hose.replaced egr with new gasket.
3)reset pcm and after 70 miles or so same mil p0401.
4)resistance at EVR solenoid is 31 ohms
5)checked ref voltage at 5.75V and sig voltage on DPFE. showing .7 volts KOEO and placed vacuum to top of egr with KOER and monitored voltage at DPFE with vacuum applied. varried from roughly 1.7v to 3.6v. depending on vacuum applied.i went ahead and replaced DPFE as a probable cause.
6) reset pcm and 70 miles later code is back
Now.....i checked all vacuum hoses and the seem ok but i have a question... am i suppose to have a constant vacuum on the EVR solenoid? Meaning the white vacuum hose from the vresser to the bottom hold of the EVR? the top hose is going to top of EGR of course. I am sorry for the long post, but I wanted to include everything so as to get the entire background. Thanks folks!