Low idle and stalling

OneSixty

OneSixty

Forum Member
Joined
Apr 16, 2018
Messages
117
Location
Outer Perth Area, Western Australia
Car Year
2003
Car Model
SG Forester 2.5X
Transmission
5 Speed Manual
My SG Forester that had been sitting for years idles at 500rpm and sometimes stalls while not being in gear. Mechanic said it could be the throttle body being clogged up from stale fuel (makes sense after seeing the condition of the fuel tank) but want to know what else it could be.
 
Throttle bottle won’t be clogged from stale fuel. It’ll be the Idle Air Control Valve that’s clogged or at least a little sticky.

Clean this out and run some clean fuel through the engine and you should be apples. As Duncan mentioned, the UEC is always a good thing to do too.

Cheers

Bennie
 
What should it idle at? My SG idles at around 650rpm.
 
That's correct - 650 plus or minus 100 SG non-turbo
 
The idle just doesn't seem high enough as its hard to take off without increasing the revs to 1k rpm which isn't easy to do.
 
I'm confused. Why is it hard to increase the revs to 1k? there should be a pedal near your right foot that can help. :ugeek:
 
I should mention that after cleaning the IACV which was black and had carbon falling out of where it is located there was no difference in idle. Still stalls randomly and idles at 450rpm. I should also mention that the engine makes a really bad noise similar to "pinking" at around 2000rpm when accelerating slowly and does it really badly when I practice driving it and have to start on the tiniest upward slope and stall it.
 
Sounds like you might have a few vacuum leaks or a dead iacv. Is the cam timing aligned properly with all the corresponding crank and cam marks? It could be out a couple of teeth one way or the other.

Cheers

Bennie
 
I read online that you can determine if the IACV is working or not by disconnecting it and comparing the idle. Apparently, if the idle stays the same the IACV is not working. In my case the idle has changed but disconnecting it seems to "fix" the low idle problem.

Untitled.png

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Not exactly sure where the vacuum lines are, tried finding a diagram but only found them for turbo engines.
 
Once my SG is warmed up, my idle is usually around about where yours is in the first picture. It does vary slightly. (Guessing because of aircon, weather ect) It did take me a while to get familiar with driving, coming from a diesel where you could take of without touching the accelerator. It is a little annoying getting the rpm up from low rpm as the petrol engine is less responsive. But I just see that rpm as normal idle and got used to it.
 
My MY06 is like Red's, and yours.

Once warmed up, idle is the same as your first picture.
 
MY05 here, pretty much the same.
 
**SOLUTION TO RANDOM STALLING AND PINKING**
Subaru upper engine cleaner, iv'e heard it was good but never expected it to be THAT good! Has completely transformed my Forester with only one can, no more random stalling, no more pinking, don't even need to keep your foot on the accelerator anymore! It just keeps going by itself in 1st and 2nd gear keeping itself at 1000rpm even in sand in 2nd high no accelerator. If your Subaru is acting up like mine was give it a gut full of Subaru upper engine cleaner and you will be amazed just like I am.
 
Amazing... Only took a year to listen to the first reply you got

You could have saved yourself a heap of time and heartache.

Happy new year!
 
Hi there @OneSixty, your SG should be fine. Make sure that the IACV is cleaned as well as the part where it mates with the throttle body. The bold line above zero (0) is the actual 500rpm.

If your IACV looks like this, another way to test it is to remove it from the throttle body housing while connected and then get somebody to put the key to the ON position while you hold the tip to make sure there is some resistance . It should go erect a bit and if it does, its still working fine. Cheers.
iu
 
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