Subaru Impreza GC8 & RS Forum & Community banner
1 - 10 of 10 Posts

·
Registered
2005 Impreza 2.5 RS
Joined
·
19 Posts
Discussion Starter · #1 · (Edited)
Hey everyone - I just barely registered for these forums but have been using them for years to help with all sorts of things in the past. So first of all, thank you to everyone in this community! Now on to my problem...

Over last weekend, I had a terrible hesitation/stutter problem during medium to hard acceleration. After a lot of research (thank you Hesitation Sticky!), I narrowed some things down and my car finally threw a CEL pointing to a misfire in cylinder one because of bad spark plug wiring.

So, I've just barely installed new plugs (OEM) and new wiring (at the same time I installed a new timing kit, I just hit 100,000 miles) - the hesitation is gone and the power is back, but a new problem has emerged: The car idles at an EXTREMELY low RPM when started (less than 500) and barely stays alive. Once I begin driving, everything feels fine, but the car will drop all RPM's and die once I stop (at a stop sign, red light, etc.). It doesn't seem to put up any sort of a fight either, the RPM's just drop and the car dies quietly. This will also happen while I'm driving if I shift out of gear into neutral - the RPM's drop and the car dies while I'm still moving, so I lose power steering and have to pull over to start the car again.

I know that the ECU needs to re-learn a number of values after a misfire, and I've gone through the steps to have it do so (see: What would cause the car to idle low after replacing the battery), but the problem is still persistent. It's only been one day since I finished replacing things, do you think I just need to give it more drive time to re-learn values? I'm extremely hesitant to take it into the dealership, as I don't want to get ripped off. Thanks in advance, fellas!

Car details: 2005 Subaru Impreza 2.5 RS, 103000 miles, manual transmission - completely stock except for a Magnaflow muffler and K&N air filter
 

·
Registered
Joined
·
92 Posts
MAF ( think 05's had maf+map), idle air control, throttle position sensor(?), ignition coil. Check electrical connections/plugs and vacuum lines. Tis all I can think of. May try attempting to induce the situation to see if a code is thrown, but it seems like it's done it a couple times already with nothing given back.
 

·
Registered
2005 Impreza 2.5 RS
Joined
·
19 Posts
Discussion Starter · #3 ·
Thanks for the response, shaz. I was leaning towards the MAF or IAC as well, I'll have time to double check those later. The throttle position sensor crossed my mind too, but I figured the car wouldn't drive as consistently if that was defective - it will drive great while in gear, no problems until I'm in neutral. On a good note, the car finally threw a CEL at me last night. I'll decode it later and let you know where it points me. Thanks again.
 

·
Registered
2005 Impreza 2.5 RS
Joined
·
19 Posts
Discussion Starter · #4 ·
Good news, the problem is now SOLVED. All the sensors were appearing fine, we pulled out the throttle body and it was pretty gunked up. We cleaned that and the air box out and everything is running much more smoothly now, a steady idle at 750 RPM's. Thanks again for your response, shaz.
 

·
Registered
Joined
·
1 Posts
I'm having the exact same issue on my '06 Impreza.

Really rough idle and stalling while driving.
Sounds like I may need to pull the throttle body as well.. do you have any instructions/write up that you followed? or any advice?
 

·
Registered
2005 Impreza 2.5 RS
Joined
·
19 Posts
Discussion Starter · #7 · (Edited)
Hey jamtim - Sorry to hear you're running into this problem too. Did you recently replace any parts of your engine, or did the problem just start manifesting itself out of the blue?

Like my car, yours could just have problems breathing because of carbon buildup in the throttle body and air box, resulting in restricted air flow. I unfortunately don't have a write up that I followed. We pulled the whole TB out and wiped it down real good. If you don't plan on removing it from the vehicle to clean it, make sure you open the butterfly and shove a rag in there to prevent any gunk from getting into the intake manifold (this is why I suggest removing it to clean it), but be careful not to bend the butterfly.

Some other relevant things you may also want to consider checking and cleaning, like mentioned above, are the MAF and the IAC, and possibly the O2 sensor.
 

·
Registered
1999 Subaru 2.5RS
Joined
·
196 Posts
posting on a dead thread here but..

I was having the same stalling problem with my 1995 Impreza L, automatic 1.8. The car would stall 2 or 3 times on the way to and from work. Usually at stop lights or when i would let off the gas and the car would try to find an idle. When it did idle, it idled low and was unstable often dipping to just a couple hundred RPM.

I took the advice of Zecher here and cleaned out the TB. It was a work night and I didn't want to risk not having the car drive-able the next day so I didn't remove the TB to clean it. I simply removed all of the plastic intake bits leading up to the TB, held open the butterfly, and used a soft rag to scrub the TB walls where the butterfly lays at rest.

I couldn't believe how much black carbon goo came out - and the car only has 93,000 miles on it! Anyways, the car no longer stalls, and the rpms don't sporadically dip when at an idle. The idle itself is a little rough, but i'm sure theres other reasons for that.

Just wanted to share my experience since it seems a little more common then I thought. I also wanted to acknowledge this forum for having great info/advice.
 

·
Registered
2005 2.5rs
Joined
·
78 Posts
Im posting on the dead thread again too, but im having low idle and stalling after getting a new battery, the car ran great for 10k miles and now i can't get a good idle, ive tried resetting the ecu a few times now and it keeps reverting to a low idle. i've had this problem before after a shop reset the adaptives after having some work done, but the car reset itself after just one battery disconnect with the startup methods described in other threads on here. could this be a tb issue even if the car ran fine 12 hours ago?
 
1 - 10 of 10 Posts
Top