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tracking down a strange idle on my 1994 4.0L w/ egr system . its a brand new ford factory rebuilt motor
new IAT, ECT, coil pack , plugs, wires,, o2 sensors, 100% new EGR system, injectors (they are sealed not leaking at the o rings im 100% on that), fuel pressure regulator, reused the IAC valve resistance @ 16 ohms ( not perfect but its functioning ) , cleaned the MAF really good , reused the TPS
basically you can hear an idle change about >100 rpm drop/gain , you cant visually see it on the tach, but you can see it on the mechanical oil pressure gauge it also drops/gains by about ~2psi
and the engine has a little bit of a shake to it (not like a loose lower intake!! ; just a slight shake )
no CEL lights as well .
ran the code check
koeo :
code 335 (egr blah blah blah )
the memory gives code 111
koer :
code 411,412,538
cyl. balance test :
3 tests consistent code 90
fuel pressure readings :
right after energizing fuel pump : 38psi
after about 1 minute of energizing fuel pump : >20 psi
engine running : ~30 psi
engine off after about 20 minutes : >15 psi
30 psi is just enough to keep the engine running, when it starts it hesitates until the pressure stabilizes at ~30 psi,
i immagine the rapid pressure drop is due to the fuel pump back check valve going out
the 3.0l engine this 4.0 replaced had a really low idle and some times sounded as if it were going to die.
im just trying to figure out it the fuel pump is the culprit , with the engine running the fuel pressure did not really fluctuate along with the idle gain/drop
does that limit it to the IAC, or the TPS ?
there was a procedure i read here for resetting the idle maybe thats a good answer?
http://therangerstation.com/forums/showthread.php?t=97524&highlight=throttle+plate+screw
im just looking for a few suggestions , ive been reading up on ideas fora bit now most everyone is all about cleaning the MAF blah blah blah, hoping for some good discussion on it.
ive also come across allot of unanswered threads, im hoping by posting this here it may help others as well + i lazy.
new IAT, ECT, coil pack , plugs, wires,, o2 sensors, 100% new EGR system, injectors (they are sealed not leaking at the o rings im 100% on that), fuel pressure regulator, reused the IAC valve resistance @ 16 ohms ( not perfect but its functioning ) , cleaned the MAF really good , reused the TPS
basically you can hear an idle change about >100 rpm drop/gain , you cant visually see it on the tach, but you can see it on the mechanical oil pressure gauge it also drops/gains by about ~2psi
and the engine has a little bit of a shake to it (not like a loose lower intake!! ; just a slight shake )
no CEL lights as well .
ran the code check
koeo :
code 335 (egr blah blah blah )
the memory gives code 111
koer :
code 411,412,538
cyl. balance test :
3 tests consistent code 90
fuel pressure readings :
right after energizing fuel pump : 38psi
after about 1 minute of energizing fuel pump : >20 psi
engine running : ~30 psi
engine off after about 20 minutes : >15 psi
30 psi is just enough to keep the engine running, when it starts it hesitates until the pressure stabilizes at ~30 psi,
i immagine the rapid pressure drop is due to the fuel pump back check valve going out
the 3.0l engine this 4.0 replaced had a really low idle and some times sounded as if it were going to die.
im just trying to figure out it the fuel pump is the culprit , with the engine running the fuel pressure did not really fluctuate along with the idle gain/drop
does that limit it to the IAC, or the TPS ?
there was a procedure i read here for resetting the idle maybe thats a good answer?
http://therangerstation.com/forums/showthread.php?t=97524&highlight=throttle+plate+screw
im just looking for a few suggestions , ive been reading up on ideas fora bit now most everyone is all about cleaning the MAF blah blah blah, hoping for some good discussion on it.
ive also come across allot of unanswered threads, im hoping by posting this here it may help others as well + i lazy.
