EGR Problem ?
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New User
Joined: Jul 2007
Posts: 2
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EGR Problem ?
1997 5.4 liter Ford Expedition, automatic trans<O
</O
Symptoms:<O</O
Idles very smooth
Runs rough (in drive) with any gradual/moderate increase in throttle.
Sometimes rough (in drive) even with steady throttle in 1500 – 2000 rpm range.
***Seems smooth (in drive) under wide-open throttle.***
The more load, add trailer for instance, symptoms get even worse.
New plugs, new boots, all coils firing.
MAF clean, and checks out
All air inlet tubing to throttle body look like new.
New air filter.
Sun Scan tool says: P1408 “EGR out of range”
21 in. hg of vacuum @ 750 rpm idle w/ engine hot at intake manifold port.
DPFE:
Reference voltage = 5
Signal voltage, cold engine = .8
Signal voltage, warm engine = ????
EGR Vacuum Regulator:
Resistance = 53 ohms
Voltage in harness = 12v
</O
EGR valve:
Very clean, all passages very clean.
Seals passage tight with no vacuum applied.
Opens easily with 4 to 7 in hg of vacuum.
Holds 7 in. hg with no leakage, diaphragm fine.
IAC valve:
New vacuum line going into rear of intake manifold under IAC valve.
Voltage in harness = 12 volts
Resistance across terminals = 11.2 ohms
Not internally short circuited.
Pintle inside very clean.
NOTE: when IAC valve out of vehicle, no voltage applied, it’s valve is partially open. Is that normal?
Vacuum readings at EGR with ‘tee’ tapped into line:
0 inches hg @ 750 rpm idle. in ‘park’
2 – 3 inches hg @ 2000 rpm in ‘park’
4 inches hg during gradual acceleration up to 2000 rpm in drive.
4 inches hg @ 1800 rpm in drive with load.
0 inches at full throttle in drive with load.
</OSymptoms:<O
</OIdles very smooth
Runs rough (in drive) with any gradual/moderate increase in throttle.
Sometimes rough (in drive) even with steady throttle in 1500 – 2000 rpm range.
***Seems smooth (in drive) under wide-open throttle.***
The more load, add trailer for instance, symptoms get even worse.
New plugs, new boots, all coils firing.
MAF clean, and checks out
All air inlet tubing to throttle body look like new.
New air filter.
Sun Scan tool says: P1408 “EGR out of range”
21 in. hg of vacuum @ 750 rpm idle w/ engine hot at intake manifold port.
DPFE:
Reference voltage = 5
Signal voltage, cold engine = .8
Signal voltage, warm engine = ????
EGR Vacuum Regulator:
Resistance = 53 ohms
Voltage in harness = 12v
</O
EGR valve:
Very clean, all passages very clean.
Seals passage tight with no vacuum applied.
Opens easily with 4 to 7 in hg of vacuum.
Holds 7 in. hg with no leakage, diaphragm fine.
IAC valve:
New vacuum line going into rear of intake manifold under IAC valve.
Voltage in harness = 12 volts
Resistance across terminals = 11.2 ohms
Not internally short circuited.
Pintle inside very clean.
NOTE: when IAC valve out of vehicle, no voltage applied, it’s valve is partially open. Is that normal?
Vacuum readings at EGR with ‘tee’ tapped into line:
0 inches hg @ 750 rpm idle. in ‘park’
2 – 3 inches hg @ 2000 rpm in ‘park’
4 inches hg during gradual acceleration up to 2000 rpm in drive.
4 inches hg @ 1800 rpm in drive with load.
0 inches at full throttle in drive with load.
Elder User
Joined: Jun 2004
Posts: 679
Likes: 0
From: Orlando, Fla
This may sound too simple, but have you checked the PCV? Plus the PCV line is known to crack and/or collapse (from tube weakness).
Your COPs may be all firing, but one may be failing and this tends to be inconsistent. I have had them suddenly die and others hang on for a few weeks without a code before giving out.
Also, if you have never checked or changed it, check the DPFE located on the driver side just ahead of the throttle body. Its about the size of a deck of cards, pot metal and has two vacuum lines coming off the bottom of it. It is part of the EGR system and the nipples off this piece will corrode shut. Buy the replacement, its plastic and thus won't corrode.
Your COPs may be all firing, but one may be failing and this tends to be inconsistent. I have had them suddenly die and others hang on for a few weeks without a code before giving out.
Also, if you have never checked or changed it, check the DPFE located on the driver side just ahead of the throttle body. Its about the size of a deck of cards, pot metal and has two vacuum lines coming off the bottom of it. It is part of the EGR system and the nipples off this piece will corrode shut. Buy the replacement, its plastic and thus won't corrode.
