Rough idle etc.
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Trailering
Joined: Jul 2007
Posts: 23
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From: Québec, Canada
Rough idle etc.
Good evening everyone.
I need to ask help on this one after reading a lot of stuff.
My truck is: 1999 F150 4x4 4.6 V8 with 325000 Km
Here is my situation: I had the famus code p0401 and a misfire a week ago.
I read a lot on the p0401 and decide to clean the tb before buying the egr valve or other parts. The misfire I was aware of it because my wires were bad, sa I change the wires and the plugs. Also I took the time to change to O2 sensors since they had never been done.
My problem is that the truck stills runs rough at idle like a misfire and when I step on it it feels really bad but it does not read any code. I check to see if I had mixte the wires or not connected the plugs right and everything looks good.
Is it possible to have bad plugs without registering any code ? Is it possible the EGR is causing this rough idle, again without a code ?
Any suggestions or comments.
Thanks for any help
I need to ask help on this one after reading a lot of stuff.
My truck is: 1999 F150 4x4 4.6 V8 with 325000 Km
Here is my situation: I had the famus code p0401 and a misfire a week ago.
I read a lot on the p0401 and decide to clean the tb before buying the egr valve or other parts. The misfire I was aware of it because my wires were bad, sa I change the wires and the plugs. Also I took the time to change to O2 sensors since they had never been done.
My problem is that the truck stills runs rough at idle like a misfire and when I step on it it feels really bad but it does not read any code. I check to see if I had mixte the wires or not connected the plugs right and everything looks good.
Is it possible to have bad plugs without registering any code ? Is it possible the EGR is causing this rough idle, again without a code ?
Any suggestions or comments.
Thanks for any help
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
A 401 code usually does not cause rough idle.
Reason is the test failure is a 'low flow' failure which means the EGR path is not open when it 'should' be, for the test..
I would not just buy and replace parts in hopes of getting lucky until you find the causes of the missfire and rough idle.
Check fuel pressure next to see what you have.
If the EGR may be open a small amount; to find this, remove the vacuum hose to see if the idle smooths out. If yes, the EVR is dirty, the EGR is able to operate and the tract is open and does not need service..
Good luck.
Reason is the test failure is a 'low flow' failure which means the EGR path is not open when it 'should' be, for the test..
I would not just buy and replace parts in hopes of getting lucky until you find the causes of the missfire and rough idle.
Check fuel pressure next to see what you have.
If the EGR may be open a small amount; to find this, remove the vacuum hose to see if the idle smooths out. If yes, the EVR is dirty, the EGR is able to operate and the tract is open and does not need service..
Good luck.
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