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IDLE CONTROL SYSTEM MALFUNCTION (FAIL SAFE)

 

Replaced in last 1000 or so miles:

piston rings

rebuilt heads

main and rod bearings

all seals on the bottom end

group n Motor, transmission, and dog bone mounts

new timing belt and all idler/ cog pullys

water pump

neutral safety switch (used from 09 forester)

IACV (used from 99 legacy)

 

i may have forgotten something.

 

I did not reset the ecu after the iacv so this may be my problem.

 

this CEL is intermittent and is night and day difference when its on and off. when its on it runs very poor, will almost stall out coming to stops (200 rpm) and will just be sort of jerky on and off throttle. not as jerky as it was before replacing the neutral safety switch but kind of. also just sort of sucks to coast it will abruptly lunge forward or back at times

 

when the light is off i couldn't ask for a better running older car.

 

what else is there that might contribute to throwing this code?

 

my grounds suck right now when reinstalling my tranny/engine (connected them outside the vehicle and put them in at the same time) i notice the trans ground wire is snapped so i've been running without it, i could have fried that neutral switch again? also reverse switch may be out or it could be the lights i haven't looked into it i just don't have reverse lights.

 

TPS? Fuel pressure regulator?

:icon_cry:

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  • 4 weeks later...
If it's a manual transmission car, I always start by replacing the neutral safety switch on the side of the transmission. When they wear out, it'll tell the ECU the transmission is in neutral when it's not. The ECU will then try and kick the IAC circuit on and makes it run like poo. It also causes stalling when coming to a stop or real low/no idle.
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it was replaced with a known good one, at least one that was in a working vehicle (09 forester).

 

now i have another code p0852 neutral switch input high circuit... Soo i;ve just been dealing with it.

 

o and i put in a IACV i pulled from the junk yard and it made no difference

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  • 1 month later...

bumpage...

 

so i got to roll around on the ground yesterday and replace another neutral switch.

 

the one on there after testing with a multi meter, i was getting 3.xxx to 6.xxx ohms inconstantly and changing back and forth very quickly. it was never infinite or high but did not just stay at zero, in neutral, like the new switch so it was replaced.

 

tested the reverse switch to and it was fine looks like i just need lights for the reverse lights to work.

 

reset the ecu and its been 20 miles no CEL, i had two P1507 and P0852.

 

still a little jolty on and off throttle response but i can live with it. a machanic said my front CVaxles (had more play than they should) are bad. i had my car inspected after the rebuild they are the originals with 198,xxx miles on them.

 

i'm leaning toward my TPS and now that i have a multimeter of my own can test some used ones out before buying. On my TPS my ohms jump around a little on smooth throttle movements open and closed.

 

what do you guys think.

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thanks for the heads up, they are probably garbage, do we have the option for those whiteline inserts, or do we have to go the route of installing all new bushings? and i know the bushing replacement is a more perminate fix than the inserts.

 

the reason I wanna look into TPS is the joltyness is accompanied by lack of throttle response. i'll try to clarify with a particular scenario that is annoying...

 

coming up to a turn or stop i have down shifted and am in 2nd gear clutch disengaged(released) and i have navigated through the turn or the flow of traffic has begun to move again at the stop. i press the petal slightly (the go petal) get nothing give her a bit more, nothing... i'd say this is about 5 to 10% throttle input and then i give it more and get that initial jolt or i back off and try again for a different result.

 

these are drive by cable and the TPS should just tell the ecu where the throttle is so idk if it would be related but is worth testing mine and looking into, as well as those diff bushings.

 

tps sweep test.

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was put on with the rebuild almost 8,000 miles ago. dakin excedy supposedly oem, original flywheel resurfaced, clutch kit is my second one because the first one broke my clutch fork and i somehow got them to warranty it, that one had the sachz flywheel.

 

i think i know what you are gonna ask, the dampening?(actually dont know if thats what they do) springs on the clutch plate might be stuck if it was older, and i can't remember if i gave them a wiggle or not before i installed the new one.

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Still thinking on possible causes.

 

O.

 

vac leaks may be possible all the rubber is old on her but we have like 4 hoses. PCV and the 2 valve cover ones and maybe one other, the purple wire harness behind the power steering pump.

 

maybe i can get a new o ring for the IAC one in there is still pliable but just old.

 

also the intake manifold gaskets are 8000 miles new

 

MAP?

 

it did do all this stuff before the rebuild, it had a p0420 CEL and that has yet to return.

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loose valves? the clearances/lash was set nearly 5000 miles ago along with a new mani gaskets. this 1507 seems to be different for everyone. thanks though

 

a little update: i have no idea why this code hasn't returned yet it still does everything the same. 130 miles and no CEL. seems like the new neutral switch just got rid of the codes and not the problems..

 

talked to my GM at the brewery i work at, used to be a mechanic at nissan, gm, and unfortunately kia. told him that i'm been almost stalling out and how my codes i;ve had have gone away but the problem is still there. we think that has to do electrical, or tps. gonna try swapping my alternator with one sitting around.

 

the idle seems to dip with electrical inputs i.e. windows and braking. My boss then went of about alternaters and AC/DC. the currents not the band, and he thinks my alternate is not producing or malfunctioning on the DC side of things, thinks i should get it tested but i have one laying around (used) so just said throw it on and see what happens

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loose valves? the clearances/lash was set nearly 5000 miles ago along with a new mani gaskets. this 1507 seems to be different for everyone. thanks though

 

a little update: i have no idea why this code hasn't returned yet it still does everything the same. 130 miles and no CEL. seems like the new neutral switch just got rid of the codes and not the problems..

 

talked to my GM at the brewery i work at, used to be a mechanic at nissan, gm, and unfortunately kia. told him that i'm been almost stalling out and how my codes i;ve had have gone away but the problem is still there. we think that has to do electrical, or tps. gonna try swapping my alternator with one sitting around.

 

the idle seems to dip with electrical inputs i.e. windows and braking. My boss then went of about alternaters and AC/DC. the currents not the band, and he thinks my alternate is not producing or malfunctioning on the DC side of things, thinks i should get it tested but i have one laying around (used) so just said throw it on and see what happens

 

Loose valves or a leaking gasket were literally the problem as I had a Subaru Master Tech do the diagnostics on it. When I pulled my exhaust mani, sure enough I found a gasket I had damaged when I put my headers back on. Valves were indeed bad when I had them checked as well. Before that, I had replaced both my Neutral and Reverse Safety switches and for a few weeks I'd occasionally see the RPM's dip down to where it was about to stall to like what you're mentioning. I think the ECU might have been trying to compensate or something, not too sure... but it wasn't permanent.

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update. no luck on the alternator got it tested by vatozone, might have them bench test it but it all checked out for now

 

gonna try and salvage a couple sensors hopefully tomorrow maybe a MAP but defiantly a TPS, need to look for a rubber accordion thing that the intake has, also maybe a sway bar.

 

the idle thing i've noticed (im gonna probably say this wrong) runs fine on the closed loop tune, where it runs without the input from the sensors. but once it warms up enough to run on the open tune where it is running from the values received from the sensors it idles crappy and wont run very smoothly. i"m gonna look into grounding issues and could deside to try a DIY grounding mod.

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i was stop and go at this stop sign for what seemed like forever so i took a video... she is a dirty girl. I would do throttle blips in first or second to to go and drop it in neutral and brake and a couple times you can see it drops almost all the way down to 200rpms. sorry about the green onions too, booker t and the mg's on a sunny day you might want to mute.

 

so i was able to pull a sensor the other day, and i tested the two side by side, i have no idea how to test the damn things so a side by side test by poking the same terminals to test each one.

 

on my original one on some of the terminals i would poke i would end up with 1 ohms and nothing would happen if you twisted the twisty part. but on the sensor i pulled i would get 0.00ohms which to my knowledge means i have continuity and it would then change when you twisted it. not always smooth transitioning to numbers it would go one way or the other like if transitioned smooth up it might jump around slightly back down. or if it smoothly came down it would jump around a bit back up.

 

ended up saying F it, it had more continuity on more terminals than my original one so i threw it on and just sort of guessed on the position, i still have to properly install it but it does seem to be working better/ different than before. smoother on/off throttle transitions and such but i think the ecu is learning to idle like poo again had it drop off a couple time after the install but definitely less than before.

 

the video is before install

 

questions? concerns? comments?

 

once again i'll keep you all posted

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