when you idle the engine at 1500 rpm the idle goes up and down. when you drive at 1500 rpm the engine stumbles and misses, with a dead spot. i have replaced the following- EGR valve,EGR pressure sensor,hoses,fuel pressure regulator,spark plugs,coil packs,pcv valve,cleaned the throtel body,replaced air filter.before i did this their was a code P0401,no code now.and before i replaced all these parts, the problem would come and go. now its always their.i used to be a chevy man,im trying to expand. signed heavy chevy.
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1997 Ford Expedition Question: engine runs rough at 1500 rpm.
Visitor, April 27, 2010, 12:26
idle air sensor is bad
ReplyVisitor, June 05, 2010, 11:44
this engine has no idle air sensor. it has a new IAC valve, the problem is the EGR is opening to soon. cruising around 1000 to 1500 the egr opens and closes causing a surging effect , a stumbling. the idle goes up and down even in park. when you put it in 4x4 low you cant maintain a steady speed because of the surging the rpm is between 1000 and 1500 if any one has the fix i would be very happy, i have spent over 1500 dollars trying to fix this . you would be surprised''' my phone# is 706 237 3864 i will cut a jig for you.
Answer #2bmdouble August 10, 2010, 22:35Journeyman
It sounds similar to an exhaust restriction.put a vacuum gauge on a vacuum line and rap the throttle while in park.the vacuum should snap back to what it was at idle.if it moves slowly to the reading at idle you have a restriction.also the baro pid is a telltale sign(if you have a scan tool available)anything in the 149hz and below is also an indicator.or if you have access to a backpressure gauge,should not read above 3psi.good luck!