EGR Valve
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Joined: Oct 2008
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From: Hernando Ms
To expand on y2kfordparts post....An "open" egr valve will create in essence a vacuum leak,causing rough idle,and poor acceleration.
By the term "open" im saying that any carbon buildup will cause the plunger in the EGR valve not to close on command properly.If you suspect a faulty EGR,you can attempt to clean the valve seat,and corresponding plunger.
By the term "open" im saying that any carbon buildup will cause the plunger in the EGR valve not to close on command properly.If you suspect a faulty EGR,you can attempt to clean the valve seat,and corresponding plunger.
Lead Driver
Joined: Sep 2006
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The level of roughness can't be determined.
If the EGR is stuck open enough, it causes exhaust gas to be introduced into the air stream making the idle lean and rough.
This also has an effect on advancing the ignition timing adding to the effect.
At road speed, the A/F ratio goes lean, timing is advanced and can result in pinging under load.
I might add that under normal driving conditions in Overdrive and light throttle the same thing happens but by intention plus reduces the amount of fuel injected.
Any other time, it usually causes drivability issues and should set a code and lamp for a P04xx code.
You can see all these effects by using a timing light to see the ignition advance as you open the EGR using a hand vacuum pump and noting the motor's response.
An EGR that does not close fast enough can be due to a dirty vacuum regulator because it is a 3 port device such that it has to let air back into the EGR diaphram in order to let it back onto it's seat and seal up once it has operated.
If the EGR is stuck open enough, it causes exhaust gas to be introduced into the air stream making the idle lean and rough.
This also has an effect on advancing the ignition timing adding to the effect.
At road speed, the A/F ratio goes lean, timing is advanced and can result in pinging under load.
I might add that under normal driving conditions in Overdrive and light throttle the same thing happens but by intention plus reduces the amount of fuel injected.
Any other time, it usually causes drivability issues and should set a code and lamp for a P04xx code.
You can see all these effects by using a timing light to see the ignition advance as you open the EGR using a hand vacuum pump and noting the motor's response.
An EGR that does not close fast enough can be due to a dirty vacuum regulator because it is a 3 port device such that it has to let air back into the EGR diaphram in order to let it back onto it's seat and seal up once it has operated.
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Senior User
Joined: Mar 2008
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From: Miami Lakes, Fl
The CEL showed P0401. It does buck around 45 but i am not getting a code for that. All plugs and COPS have been changed within six months.
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Lead Driver
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Put another way; this 'function' has been designed into most Ford vehichles since 1973.
It purpose is to recirculate a calbrated amount of exhaust gas into the intake during "CRUISE LITE THROTTLE" as a way to reduce nitrigen oxide emissions demanded by the EPA.
The system is designed to advance ignition timing because the mixture is so lean the ignition point has to be started earlier.
If any coil has low output, it will show up as a miss since that coil can't reliably fire a very lean mixture.
.
The system reduces fuel injection amount because the poor air quality by the exhaust contamination cannot support normal amounts of fuel and is done to help fuel mileage.
These actions are adjusted and controlled to make the total intended action, smooth and transparent.
.
As soon as more engine load is called on or rpm range has been fallen outside limits, the PCM sees this by throttle sensor position and speed, then stops the EGR function pulling all changes out, as stated above.
The EGR has two purposes; to reduce emissions and to improve fuel mileage within the most used engine operations, in a smooth manner.
.
Any other operation or fault at (other times) 'will' cause drivability issues.
It purpose is to recirculate a calbrated amount of exhaust gas into the intake during "CRUISE LITE THROTTLE" as a way to reduce nitrigen oxide emissions demanded by the EPA.
The system is designed to advance ignition timing because the mixture is so lean the ignition point has to be started earlier.
If any coil has low output, it will show up as a miss since that coil can't reliably fire a very lean mixture.
.
The system reduces fuel injection amount because the poor air quality by the exhaust contamination cannot support normal amounts of fuel and is done to help fuel mileage.
These actions are adjusted and controlled to make the total intended action, smooth and transparent.
.
As soon as more engine load is called on or rpm range has been fallen outside limits, the PCM sees this by throttle sensor position and speed, then stops the EGR function pulling all changes out, as stated above.
The EGR has two purposes; to reduce emissions and to improve fuel mileage within the most used engine operations, in a smooth manner.
.
Any other operation or fault at (other times) 'will' cause drivability issues.
Lead Driver
Joined: Sep 2006
Posts: 7,907
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401 code is the result of a flow test done by the computer.
The code is 'insuficient flow'.
Not one due to excessive or stuck open EGR flow.
To save me and others time and typing, search for this fault that had been covered over and over for many years, for the causes, explanations and sources of the cause.
Low flow is the hint! read blockage, non operation etc.
Your miss as 45 has also been hinted on in the above reply.
The code is 'insuficient flow'.
Not one due to excessive or stuck open EGR flow.
To save me and others time and typing, search for this fault that had been covered over and over for many years, for the causes, explanations and sources of the cause.
Low flow is the hint! read blockage, non operation etc.
Your miss as 45 has also been hinted on in the above reply.
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Senior User
Joined: Mar 2008
Posts: 147
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From: Miami Lakes, Fl
OK
I pulled the EGR and TB and cleaned both and still had the p0401. So i checked all the hoses and connections, did a vac check on the EGR and it check OK. Still getting the P0401. I then changed the EGR solenoid and still the P0401. So after all else and according to Murphy's Law I changed the DPFE and that fixed it. All this plus the Heater core went out on the middle of this.
But right now all is well.
Thanks for all the help
Dan
I pulled the EGR and TB and cleaned both and still had the p0401. So i checked all the hoses and connections, did a vac check on the EGR and it check OK. Still getting the P0401. I then changed the EGR solenoid and still the P0401. So after all else and according to Murphy's Law I changed the DPFE and that fixed it. All this plus the Heater core went out on the middle of this.
But right now all is well.
Thanks for all the help
Dan
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