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Old 09-21-2005, 04:12 PM   #1
Scooby Newbie
Member#: 67584
Join Date: Aug 2004
Location: Swamplands, PA
2004 3,0 Outback

Question idle issues, EJ25D, P1507, and more

searched all the likely places for P1507 tips, so BTDT. they all pointed me to the IAC but it's not that.

background: bought a used '97 EJ25D identical to the one in my '97 Legacy Outback, but with fresh head gasket repair. runs fine but idles high (~2500). i suspect the PO also had idle issues because the water hose to the IAC was GONE. (got to pull the fresh engine to discover that trick...) and the top of the IAC (the electric servomotor part) was adjusted fully anti-clockwise.

so i pulled the IAC from my old engine which ran fine but for the bad head gaskets. verified free and easy operation, ran solvents through it, tested the resistance, gives every indication it's good. installed it - same thing. adjusted the top fully anticlockwise like the one that came on the 'new' engine and it's driveable although it still mostly idles around 1750 and will throw P1507 when hot, in neutral especially, also when stopped, in D.

*sometimes* it'll idle happy around 1100 neutral, 950 D.

it does this even when the throttle cables are *disconnected* so it's not just that they're too tight.

i've done the usual check-for-vacuum-leak games, listening with a hose and spraying with carb cleaners and propane. found no indications of vacuum leak, although the short-term fuel trim shows about -3.5% (lean) when it's doing the fast-idle thing.

questions - aside from what have i not checked that i should...
1) what is the idle *supposed to be* ? the emissions sticker doesn't say. the manual says check the emissions sticker.
2) everything says don't tinker with the idle screw. OK, i didn't, but i have no confidence that some DAPO didn't. how do i baseline this thing?
3) what is a "normal" idle %-throttle opening ?

i'm thinking maybe there is a sticky throttle situation, possibly in conjunction with other issues. it doesn't *act* sticky, but i see varying %-open numbers and i have to wonder what i should be seeing.

i do have access to realtime ODB-II data...

thanks in advance!
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Old 09-22-2005, 04:40 PM   #2
Scooby Newbie
Member#: 67584
Join Date: Aug 2004
Location: Swamplands, PA
2004 3,0 Outback

Default Followup...

Noticed one big difference between the "good" (old) throttle body and the new(er): on the original, there is about 1/8" deadband movement before the cable sector (both) hit the actual throttle arm. the new engine had essentially no deadband -- one cable had a little, the other had zero.

so i took some big pliers and bent the throttle arm so it'd be the same for both cable stops. now there is no deadband on either one. but - got a nice stable 900 rpm idle (hot) right after. that was last night.

today i got about 1500 rpm cold/900 rpm hot and for the first time since installing this engine got NO CODES on my trip to work today.


so for now i'm prepared to call it "good enough"

it looks to me as if the 'throttle actuator deadband' is determined by the throttle stop screw, although both the new and old screws appear to be extended virtually identical amounts. i'm a little concerned that there should be *some* deadband, but i am prepared to accept my seemingly successful result and stop tinkering as long as everything continues to appear to run right.

is there really no official answer to any of my three questions?
did i just ask in the wrong place ?
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