idle issue with dimming lights and stalling

[R-raid]

So my subaru impreza rs 2000 has a very strange idle issue. One I have not read on these forums. During stops (and this immediately starts right when I turn on my car) the car will drop in idle from about my normal 600 to 500 rpms.

I have a custom magnaflow exhaust which is loud, so this change in rpms is very noticeable. I have noticed that its almost as current as a beating heart and it gets more aggressive the longer I stay in neutral or at a stop.

-there is no CEL
-the lights on my dash dim when the rpms drop <<<<<<<
-the car runs fine while moving even a little bit (throttle ingaged)
-It is not my TPS, or MAP, or Plugs or Wires

Could this be related to a fuel injector being bad? Maybe?
any ideas. I don't think its a cylindar compression issue because of how the car corrects its low idle after falling. then is normal, then falls again.


Any help is appreciated


update
also acceleration is very rough from stop as well.

Im thinking alternator or fuel injectors

update
this morning I was driving to work and the car kept adjusting itself back to normal idle speed. As I kept going at stops the car would start to lower in rpms adjust, lower again. to the point of getting to 100 rpms then stalling...

anyone
even if your not sure your right..

[Hero]

There are two things i can suggest for you;

Clean the IAC (if you have one)
Check for loose grounds attached to the intake manifold. If yours is anything like mine there is a ground on the driver's side front portion of the manifold and there is also one on the passenger side front on the lower portion of the manifold. It's a long shot, but it wouldn't hurt to check.

[R-raid]

There are two things i can suggest for you;

Clean the IAC (if you have one)
Check for loose grounds attached to the intake manifold. If yours is anything like mine there is a ground on the driver's side front portion of the manifold and there is also one on the passenger side front on the lower portion of the manifold. It's a long shot, but it wouldn't hurt to check.

hey thanks for the post. IACV has been cleaned beyond belief. but thanks for the comment on the grounds i will check them.

I am going to do some alternator tests today.
thats my #1 culprit right now

[twza-leggt]

i had a nissan sentra ser that wouldnt idle correctly and it turned out to be the crankcase sensor, but im no mechanic. lights dimming sounds like an alternator, check its voltage when running

[subaru_crazy]

do a load test on the alt if it dies thats the problem

[Berge56]

Might be time to replace the IACV... I had to replace mine after 98k since cleaning would not fix the problem.

[boxer3maine]

a boxer can exceed the low side rpm threshold of an alternator.

the old ones were notorious for this (I hypermile with a 450-600 rpm) the alternator needs almost 700rpm even on my own old car...with no electronics and there is LED swaps for 25% of the bulbs.


a bonus to this, is in that he engine is very content at being content.
opening exhaust may need to increase idle, and that means fuel mileage. You want fast and tokyo furious, you have to suck the petro down like a v8. :unamused:

a guru with the injection could fix it in no time.

[R-raid]

a boxer can exceed the low side rpm threshold of an alternator.

the old ones were notorious for this (I hypermile with a 450-600 rpm) the alternator needs almost 700rpm even on my own old car...with no electronics and there is LED swaps for 25% of the bulbs.


a bonus to this, is in that he engine is very content at being content.
opening exhaust may need to increase idle, and that means fuel mileage. You want fast and tokyo furious, you have to suck the petro down like a v8. :unamused:

a guru with the injection could fix it in no time.

not trying to be harsh. but i have no idea what your talking about
could u explain more

[R-raid]

and new symptom.

The car now stalls when idling
It runs fine if the car is turned on, but once it warms up is when the problems occur.
the car gets lower and lower in rpms. if i turn on my air conditioning the rpms go up and prevents the car from stalling.

new symptom, maybe this will help u guys help me
I also checked the alternator with volt meter, got low 14 reading so that checks out. the IACV has been cleaned and is not the problem

[Brian313]

Bad battery? Have the alternator tested under load (local parts store can help) and have the battery load tested also.

[R-raid]

Bad battery? Have the alternator tested under load (local parts store can help) and have the battery load tested also.

what do you mean by under load?

[Gearhead Geek]

what do you mean by under load?

Load testing an alternator basicly, well, puts an electrical load on it, then measures the amperage that it can put out to make sure it can still put out what it's supposed to (which, these days, on cars, isn't much more then what the vehicle needs for proper operation).

[shtbxr22]

you try cleaning the throttle body? around the throttle plate there will probably be a ton of build up. maybe a vacuum leak?

[R-raid]

Load testing an alternator basicly, well, puts an electrical load on it, then measures the amperage that it can put out to make sure it can still put out what it's supposed to (which, these days, on cars, isn't much more then what the vehicle needs for proper operation).

so is all they are doing is a voltage check. or is it more than that.. when doing a voltage check the reading is suppose to be between 14 and 15. mine was 14.23 DCV. is that what they would check or is there more to it then that

[R-raid]

you try cleaning the throttle body? around the throttle plate there will probably be a ton of build up. maybe a vacuum leak?

yep

throttle body clean
map sensor clean
o2 sensors new
wires and plugs new
coilpack new
iacv cleaned

im still leaning towards the fuel injectors. im not sure if its an electrical issue im having. I think the lights dim because of the engine shutting down. which would be the culprit of a mechanical issue not an electrical issue. the alternator passed my tests today so im not really sure its the alternator. Plus the symptoms are suppose to get worse if the a/c is turned on if the alternator is going. when my a/c turns on it almost keeps the engine alive so it doesnt stall but still pulses in idle trying to maintain the idle

no ones heard of this. the symptoms are very distinct

[R-raid]

got new fuel injectors, they sent me the wrong ones. lame. so i wait

[boxer3maine]

another odd subaru trait... for dim lights and low idle

stuck pcv. (positive crankcase ventilation)

I guess it is an aurora of bizarre out of this worldly "things" if pcv is too big, wide open, or closed (and that just aint gonna happen), it is not only a vacuum leak, some energy is getting taken away rapidly ...engine fire ground? who knows.

worth a check.

[The Internet]

I would lean toward a vac leak. Spray some MAF or TB cleaner around the hoses and see if the idle changes. Someone did that for me :) and we saw that a hose under the intake was crap. I had the same symptoms as you.

[R-raid]

I would lean toward a vac leak. Spray some MAF or TB cleaner around the hoses and see if the idle changes. Someone did that for me :) and we saw that a hose under the intake was crap. I had the same symptoms as you.

Thanks, I will try this out. is it a big change in idle?

[The Internet]

Big enough to notce. It is easily repeatable so you can continue to just give little squirts in different spots and just listen for the change. I think we also unplugged the MAF so that the idle didn't self adjust.

[R-raid]

so i tested the iac valve and thats fine. drove the car too the grocery store and the cel came on. misfire on 1 2 3 4. The coilpack is new so i checked the wires and plugs and they have oil all over them. coming out of the spark plug holes.

same problems previously stated still exist


anyone?

[shtbxr22]

you need to replace the spark plug pipe seals. you will need new valve cover gaskets, and new grommets as well. common for misfires caused by leaking oil into the spark plug pipes.

[R-raid]

you need to replace the spark plug pipe seals. you will need new valve cover gaskets, and new grommets as well. common for misfires caused by leaking oil into the spark plug pipes.

would this cause problems like the cars stalling at idle and bad initial acceleration

[shtbxr22]

the oil causes the misfires, so it is possible.

[JaketipsByBlood]

Any new news on this?

[DHGurs]

Any new news on this?

Is this Jake's old red beast?

[JaketipsByBlood]

No, he sold that before hand. This is his 98 2.5RS with an AVO kit

[DHGurs]

I thought you had that? R-Raid's car is a SRP 2.5, so I thought maybe that was his old one, although that was an L wasn't it...

[JaketipsByBlood]

I do now have it. I believe....it was an L?

The RS is a pita. Runs nice one day, then cuts out when coming to a complete stop...sometimes while stopping. If not that, ildes like crap where it will pretty much die but then revive itself. So besides the slight noise in the motor and a crap TO bearing, it's kinda annoying.