new development: odd idle

JLHollowX13 · #1 04-14-2008, 11:23 PM

so my svx has been pretty good lately, i had done a few quick mods that seemed to improve the driving such as the ecu crush, intake resonator removal, and a few other things. but today while i was driving around town, i noticed that the car has a sort of rough/very low idle and almost feels like it wants to die. it has never done this before so im pretty baffled. ill give as much info as i can to see what kind of help anyone can give me.

first off this weekend i took the svx on the longest drive i have ever taken with it. 3 to 3.5 hour drive (one way) to gunnison CO from here (divide) and back. not sure on the miles, but i do know i went through a tank of gas, give or take a little. i actually got my first ticket in the svx, and my first ticket ever. going 78 in a 55. my speedo doesnt work, but i didnt tell the cop that.

also, today i went down to colorado springs, about a 45 min drive one way from here, it was in the low 70's. this is when i noticed the low idle. my gf mentioned that the reason it was doing it was because it was so hot (we are used to the cold weather) and the car didnt want to do anything. so im not crazy, someone else noticed it too! haha

i should also mention that all day the engine temp stayed in the middle perfectly, but when i came back up here i went to my gf's house for awhile. i was there for 2 to 3 hours and when i went to leave and i turned the key, the temp guage was still above cold, maybe 1/4 up. it has always gone down all the way (where it is when the car is off) whenever i let it sit for more than an hour.

so here are the symptoms:
1. VERY low idle (imo) rpms are right at the large dash directly above 0

2. sort of rough idle. the rpms will jump slightly and i can feel the car vibrating as the rpms jump which has never happened. it is a noticeable change. the rpms dont look as if they are changing unless you look closely but you can definitely feel the car.

3. when the car was in park i got out and listened and it was revving slightly, then almost dying, revving slightly, almost dying, etc, etc. but sort of quickly, not slow. maybe a rev and almost die about twice each every second. it sounded as if i was giving it a little gas and letting off very fast. this continued as i gave it a little gas until i got the rpms to about 1500 or more, then it would sound normal until it reached almost 0 again and start over.

4. im actually very surprised the car didnt die on me at all. it REALLY seemed like it would have. it was just idleing so wierd and low that i thought it would die and i would be stranded.

5. i do get an engine code for my speedo (which is obvious) and also my iac valve. but the iac valve one rarely comes on, 99% of the time its from my speedo stuff being screwed up. i think the iac valve could be a culprit, but like i said, it rarely comes on for that and it has been a code ever since i have owned the car and it has never acted like this. if anyone could give me any tips on cleaning it or something to get rid of the code and maybe fix a potential problem i would appreciate that.

what is NOT happening:
1. the car is not dying.

2. no hesitation when accelerating

3. drives just fine at any speed, the only problem is when it is idling.

4. the car is not having any problems starting at all.

just some info that probably should be included:
1. i did search for idle problems, but none really sounded like what mine has, although i did read something about an egr hose. im not sure where this is, but i thought i could look at mine and see if it is broken or anything, so can anyone point me to it?

2. i changed the spark plugs the weekend before last. took out the intake resonator then, and also did the ecu crush mod. also changed the oil too. i did have the intake off to get to the spark plugs, but i made sure everything was hooked back up, i will double check the hoses in case one fell off or something, not sure if they could even cause this.

if there is something missing just let me know, im not sure what else to include and i feel bad that this is such a long post, but i figured id give as much info as i could as to not waste anyones time posting something that isnt neccessary. so i apologize for such a long post and im sorry if it was hard to get through, but im trying to be thorough. thanks for any help, i really appreciate all the time everyone puts into this site with helping eachother out.

im sorry if this is a total waste of time and the whole problem is in fact the iac valve, but i just want to make sure because i dont think that it would all the sudden just cause this since it has always been a code and it has never acted up. i think it may be part of the problem (hence asking how to clean it) but i think there is something else making it do this too. thanks agian!

Trevor · #2 04-15-2008, 04:51 AM

Both the Bypass Air Control Solenoid Valve and the Auxiliary Air Control Valve are involved with idle control. Not sure which you are referring to by iac (inlet air control) valve but whatever, the code makes sense and this should be your first priority.

Thanks for the complete run down and not leaving out any clues.

JLHollowX13 · #3 04-15-2008, 12:49 PM

the iac valve i am referring to is actually the Idle air control valve. sorry for not mentioning that part. im going to get some maf cleaner today just in case. anyway, about the iac valve, ive heard that some people just clean it, ive tried but i cant even find the thing so any tips on that would help. i dont want to buy a new one because i think i priced it at around 200 or something on Subaruparts. id rather clean it if possible, which i will do as soon as i find the dang thing haha. thanks again!

Trevor · #4 04-15-2008, 05:19 PM

Quote:

Originally Posted by JLHollowX13

the iac valve i am referring to is actually the Idle air control valve. sorry for not mentioning that part. im going to get some maf cleaner today just in case. anyway, about the iac valve, ive heard that some people just clean it, ive tried but i cant even find the thing so any tips on that would help. i dont want to buy a new one because i think i priced it at around 200 or something on Subaruparts. id rather clean it if possible, which i will do as soon as i find the dang thing haha. thanks again!

I recall reports of some having success by simply squirting cleaner at it via the intake. You may be able ti find the threads by way of a search.

This write up should assist you:-

By-Pass Air Control Solenoid Valve
Cleaning, setting and Testing.

Description.

The By-Pass Air Control Solenoid Valve, or Idle Air Control Valve, allows the Engine Control Unit/Computer, to control an adjustable inlet of air in order to control idle speed when the throttles are shut. One obvious function is to increase the airflow when the air conditioning system imposes an extra load on the engine. The SVX has a second valve, The Bypass Air Control Valve, to supply extra air during cold starting.

The unit comprises a rotary solenoid valve, biased towards a central rest position by means of a permanent magnet. A double wound coil provides reversing open closed operation from a mean rest position, at which point the valve is half open. This arrangement provides two way variable control, dependent on the applied voltage.

Adjustment of the mean position is provide for by incorporating slotted screw holes in the housing, probably to allow the position to be set during manufacture in order to allow for anticipated tolerances.

Three electrical connections are involved. The centre pin on the connector is common to both windings and is energised positive. The remaining two connections provide for open and close operation of the valve via negative circuits.

Cleaning and Adjusting.

Cleaning is best achieved by removing the solenoid coil by undoing the two attachment screws, which pass through slotted holes so as to provide a degree of adjustment. Make a scratch mark, so that the original position can be retained after reassembly. Magnetic force will be apparent as the solenoid coil is separated from main body.

The armature which rotates in ball races, when moved by hand should rotate open closed, with virtually no resistance. The valve should be cleaned of foreign matter using a suitable solvent/lubricant so that is completely free to move.

After reassembly the valve should rest in a position, half open and half shut when set to the original mark. If there is a large discrepancy, this may indicate that the setting has been tampered with at some time and it should be reset.

Testing.

The solenoid resistance should measure 9 ohms, each side of the common connection, i.e. 18 ohms overall, a small tolerance being acceptable.

With positive to the common connection, 8 volts DC applied alternatively to the two remaining connections, should fully open and close the valve from rest. Return to the rest position should occur reliably without hesitation. In the event that 12 volts must be used, this will suffice for intermittent testing, but the extra torque available must be appreciated,

If a variable voltage source is available, continuous opening closing according to the applied voltage can be reproduced. However this more critical test is in no way a necessity.

JLHollowX13 · #5 04-15-2008, 10:42 PM

yep that helps! i tried spraying some carb cleaner into my throttle body (which is where i think the vavle is) when i had the intake off but the car wouldnt even stay running, i think it was because the maf was not getting any reading since no air was flowing by it. i think im going to try to take the throttle body off and clean it and look up some more components that could be causing this trouble and clean them. if i still am having the same trouble then i guess im probably gonna be looking at something to do with the fuel. maybe injectors, pump, lines, filter, whatever else. ill just have to see i guess. thanks!

JLHollowX13 · #6 04-16-2008, 09:05 PM

so i went ahead and took off my throttle body and cleaned everything, in the middle of a blizzard at 20 degrees F mind you. id say im pretty in love with my car haha. anyway, i cleaned the iacv and the throttle body using an entire bottle of carb cleaner. it was looking good and while everything was out of the way i checked all the hoses and stuff and nothing looked damaged, everything looked in good shape and connected.

i put everything back together, let it warm up to 1/4, then it was idling the same as it was before so i thought maybe i needed to clear out the carb cleaner that may have been left over. i took a little trip into town, about 7 miles, and the idle was still wierd. i dont know what else to do at this point. i also cleaned the maf with maf cleaner yesterday and again today.

by the way, my cel didnt come on the entire drive so i THINK i might have fixed the iacv trouble code i was getting, but im not putting it passed my car to throw it yet. i didnt clear the codes because i was freezing and i figured id do it later. ill try to do it tomorrow though.

so does anyone have any input on this?

something i thought i would throw out there is that when i took my aicv off of my tb i noticed a little green sliding thing on the aicv where it meshes to the tb. anyway, i could slide it to the side and it would sort of spring back, but never close all the way. it would stay about 1/2 open all the time. is that what opens and closes according to the idle? i was thinking maybe that is the part that is messed up and it is just not closing fully when it should be, or vice versa. if so can i fix it or does it require a new aicv? i dont have tons of $ to get a new one so i hope its fixable or not the problem all together.

if the aicv isnt the problem what else can it be? do i need to adjust the throttle cables possibly? tps? i just dont know what else it could be.

id like to thank billb for the write-up on cleaning the tb, taking it all apart, etc and also trevor for putting that info on this thread too! thanks!

but if anyone can help me out id really appreciate it, i want my car idling right, i hate pulling up to a drive thru or at a stop light and it sounds like my car is pulsing. i need any info i can get at this point. i dont know where to turn. thanks everyone!

YourConfused · #7 04-16-2008, 09:15 PM

have you tried the tps how-to?
you know adjusting the tps.
see if it is in spec?
maybe bad?
if you can get it checked w/ an o-scope to see if there are bad spots?
just thoughts here, no solutions

otherwise I would have thought the IAC cleaning would have made your car happy

Trevor · #8 04-16-2008, 09:48 PM

Quote:

Originally Posted by JLHollowX13

so does anyone have any input on this?

something i thought i would throw out there is that when i took my aicv off of my tb i noticed a little green sliding thing on the aicv where it meshes to the tb. anyway, i could slide it to the side and it would sort of spring back, but never close all the way. it would stay about 1/2 open all the time. is that what opens and closes according to the idle? i was thinking maybe that is the part that is messed up and it is just not closing fully when it should be, or vice versa. if so can i fix it or does it require a new aicv? i dont have tons of $ to get a new one so i hope its fixable or not the problem all together.

I described the B-PACSV fairly fully, but am unable to exactly identify the part you describe. If you are describing the shutter type rotary component which directs the air flow, from what you advise, things appear to be in order.

JLHollowX13 · #9 04-17-2008, 06:20 AM

i read about thing sliding thing i described later last night after i posted in your post about cleaning and testing it. this is what you posted:

The unit comprises a rotary solenoid valve, biased towards a central rest position by means of a permanent magnet. A double wound coil provides reversing open closed operation from a mean rest position, at which point the valve is half open. This arrangement provides two way variable control, dependent on the applied voltage.

that was just a part of it, but it seems like everything in your post trevor is talking about this part that deals with testing and some cleaning. from what your post was describing it seems that it is the same thing that i am talking about. if i end up taking it all apart again (which i hope i dont have to do, but may if i do the tps thing) i will snap a picture or 2 and put them on here just so you know exactly what im talking about, maybe i should have done that from the start. note to self: take pictures.

also, i might try the tps thing today. ill have to find the how-to and print it up for directions and see wherer that is getting me. thanks!

lilbrudder · #10 04-17-2008, 12:40 PM

i don't know if you tried this but have you checked vaccume hoses? i had a small vac line on the passengers side of the motor toward the rear that was cracked causing a strange rough idle, $1 of small diameter hose fixed it. the way i found it was taking starter fluid with a very fine mist nozzle and spraying it at one section at a time with the motor running untill the motor started to race. this is probably not a good way of doing it, but don't over look the small things(vac lines).

Trevor · #11 04-17-2008, 08:57 PM

Quote:

Originally Posted by lilbrudder

i don't know if you tried this but have you checked vaccume hoses? i had a small vac line on the passengers side of the motor toward the rear that was cracked causing a strange rough idle, $1 of small diameter hose fixed it. the way i found it was taking starter fluid with a very fine mist nozzle and spraying it at one section at a time with the motor running untill the motor started to race. this is probably not a good way of doing it, but don't over look the small things(vac lines).

Spot on, thanks.

There are several vacuum hoses which must be considered as suspect and the simple can be overlooked when raising issues with the more complicated stuff.

etz bseder · #12 04-17-2008, 09:27 PM

You should check all the hoses that hold air. There are two that are most involved and may be cracked/loose. Sorry about the picture, but I no longer have an SVX for the time being.

Follow the red dots, they are on the two lines, and the lines go under the intake manifold. The replacement parts are available from Subaru for fairly cheap, and really did the trick for my car.

JLHollowX13 · #13 04-17-2008, 10:29 PM

i have checked most of the hoses, but it definitely wouldnt hurt to do it more thoroughly. i have also replaced a couple of the smaller ones, including one of the ones that connects to the top of the tb. (pass side on lh drive).

can even the smallest hole cause such problems? or does the hole need to be pretty big? because when i took off my intake the underside plastic, right where 2 hoses connect into it seemed like it wasnt sealed up right. maybe i will try sealing this up, i didnt think anything was getting through there, but i could be wrong. i will seal this up asap and see if i have any change, but what can i use to seal it with? while i have everything off i think i will go ahead and use an air compressor and a blower to test the hoses for any leaks, ill just plug one end up and put the blower in the other and if there are any leaks ill know. but if anyone knows what to use for a seal on the plastic intake i will get it and try to see if this thing is leaking air. thanks again!

GreenMarine · #14 04-18-2008, 01:14 AM

Quote:

Originally Posted by JLHollowX13

i have checked most of the hoses, but it definitely wouldnt hurt to do it more thoroughly. i have also replaced a couple of the smaller ones, including one of the ones that connects to the top of the tb. (pass side on lh drive).

can even the smallest hole cause such problems? or does the hole need to be pretty big? because when i took off my intake the underside plastic, right where 2 hoses connect into it seemed like it wasnt sealed up right. maybe i will try sealing this up, i didnt think anything was getting through there, but i could be wrong. i will seal this up asap and see if i have any change, but what can i use to seal it with? while i have everything off i think i will go ahead and use an air compressor and a blower to test the hoses for any leaks, ill just plug one end up and put the blower in the other and if there are any leaks ill know. but if anyone knows what to use for a seal on the plastic intake i will get it and try to see if this thing is leaking air. thanks again!

I used JB Quick to seal up my cracked plastic intake tubing where that vacuum hose (that they were talking about earlier, and in the picture) attaches to the plastic... JB Quick works great!!! Used it on many little "fixes" in the car and haven't had any problems with any of them after that

~ Chris

JLHollowX13 · #15 04-18-2008, 07:43 AM

awsome! ill have to pick some up today and try to slap it on there...... actually i just noticed something, if that hose that the red line is reffering to connects to the bottom part of the intake then that is where mine is "cracked", but i think on the opposite side. ill just have to check it out and see what i can do, thanks!