Idle dips to 275?!!!

[Lawsonmh15]

Well, since I have had my car, the WARM idle has NEVER been above 4-500. Now with the cold weather hitting (going snowboarding tomorrow ) I have noticed a few little idiosynchrocies.

 

1.) After warm, the idle does NOT drop to acceptable running speed, UNLESS I am sure to come to a complete stop for a few seconds. The obvious problem with this is fuel efficiency/performance. The other result is that until I do this, it shifts HARD. You can just tell it ain't right.

 

- I was at Super Rupair and was discussing it with one of the techs who said vac, I said no, explained more, and we both agreed on IACV. So, I will be cleaning that today and will leave pictures and step by step when I'm done. It should be noted that the low idle does NOT result in poor operation. There is NO shudder from it running that low. I don't know HOW that is possible, but am wondering if my climate could have something to do with it.

 

 

2.) The other prob is what HAS to be heat-shield rattle. Only rattles when foot on break, and put in Drive. Back to neutral... Gone. This appeared AFTER having Midas throw on my front o2 sensor. The ONLY reason I took it to them was because the clamps were rusted and wanted to be CERTAIN that I got NEW ones on. They will fix... Oh yes... They will fix.

 

 

SO...

 

Any suggestions on cleaning the IACV? I plan on using the BG 402 cleaner that I use on my MAF Sensor.

 

BTW. I swapped my busted pulley for a new MAF hoping it may solve my low Idle issue, but no change. SO..... The 402 is acceptable for cleaning IMHO as I have used it for several months and appears to be fine. If someone could leave the resistance I am looking for across the MAF, as well as which leads to backpin for the reading, it would be greatly appreciated.

[rainbow123]

i have the same low idle problem, although it's normal climate here in no.cal, every morning after driving the first 2 miles or so and stop at a light, it momentarily goes down to about 200-300, normal idle would only amount to 400-500, i don't bother with it it never stalls or shakes or anything

 

i also have the heat shield loose, last time i looked at it switching the halfshaft but it wasn't going anywhere so i never bothered with it

[tunered]

if i understand this ,now you have a fast idle? sounds like coolant temp to me.

[Lawsonmh15]

if i understand this ,now you have a fast idle? sounds like coolant temp to me.

 

No, Low idle.

 

Cleaned IACV.

 

No change.

 

Re-installed twice, Forgot the donut the first time. Oh well. Will list noticeable differences after enough "testing".

[trxeslr66]

I got a low idle about a month ago, asked my mechanic, he said the throttle body is prob gunked up so he cleaned it. It didnt fix the idle but it did cause my check engine light (CEL) to come one. Since them I've tried everything to fix it. The code was for the idle air control valve so I tried cleaning that and it didnt help. But when putting it back on I noticed that you could adjust the electric part to increase the idle to about 750. Its been running fine but I got another CEL. Havnt got the code from it yet but I suspect its the same p1507 IACV malfunction that i got 3 other times this month. Frusteration. Let me know if you find a fix.

[later, Peter]

Isn't there a temp sensor (cold weather idle) for this engine? If it idles ok after the engine reaches full op temp.... wouldn't that indicate a temp sensor of some kind?

Later,

Peter

[Lawsonmh15]

I got a low idle about a month ago, asked my mechanic, he said the throttle body is prob gunked up so he cleaned it. It didnt fix the idle but it did cause my check engine light (CEL) to come one. Since them I've tried everything to fix it. The code was for the idle air control valve so I tried cleaning that and it didnt help. But when putting it back on I noticed that you could adjust the electric part to increase the idle to about 750. Its been running fine but I got another CEL. Havnt got the code from it yet but I suspect its the same p1507 IACV malfunction that i got 3 other times this month. Frusteration. Let me know if you find a fix.

 

1.) Sorry to hear that man. Cleaning up the TB causing a CEL. I wouldn't go back there.

 

2.) What were you cleaning it with? Where were you cleaning?

- I'll post picks of mine dissassembled.

 

3.) What setting on the top for the 750 Idle? A, B, or C?

 

 

PICS:

 

From Passenger Fender:

 

 

Before:

 

 

 

After:

 

[trxeslr66]

I'm not sure what your asking about the A B or C? But since I posted, I now have a 2000 rpm idle so I ordered a new IACV. My mechanic cleaned the TB so I dont know what he used. And I dont even know exactly what they took apart.

[zyewdall]

Have you checked it with a shop tach? I have a hard time seeing it actually idling at 275rpm without shuddering and sounding really bad. Even 400 sounds really low to run smoothly. Is is possible that the tach is just reading a little lower than reality?

 

How was the powder???? I haven't been up there yet, but I did get 50mph blowing snow at my house in Ward saturday night... so it looks like it should be getting good up in the high country.

[Lawsonmh15]

Have you checked it with a shop tach? I have a hard time seeing it actually idling at 275rpm without shuddering and sounding really bad. Even 400 sounds really low to run smoothly. Is is possible that the tach is just reading a little lower than reality?

 

How was the powder???? I haven't been up there yet, but I did get 50mph blowing snow at my house in Ward saturday night... so it looks like it should be getting good up in the high country.

 

Haven't checked on another tach.

 

However, Now when I sit in neutral when warm with foot on break, the RPM doesn't rise, but will stay the same and fluctuate by 100 RPM or so. Earlier today it would jump to 900 in Neutral then drop to about 100, almost die, then return to about 400, then repeat the same process every 10-15 seconds or so. Got home, reinstalled AFTER coating gasket in oil, now just doesn't increase in RPM in neutral and seems to fluctuate by about 100 RPM as I mentioned. I AM STUMPED. Replaced a vac line that tore, not seing or hearing any other leaks...

 

Please let me know if you have any ideas.

 

TIA.

 

As far as the powder went...

 

It was there; but so was EVERYONE with a 5 mountain pass. I got there around 9:30 stayed till 2:00 and got THREE runs in. 45 minute lines were a joke... COULD have been a good day though.

[trxeslr66]

When my idle gets to 250 it does shake, shudder and occassionally stall. Now after cleaning the IACV it seems to be stuck open at 2000 rpm. After cleaning it was good for 100 miles then went to 2000. So I bought a new IACV and will iinstall it tonight. Hoping it fixes the low idle, high idle, and CEL!!!!

[Lawsonmh15]

When my idle gets to 250 it does shake, shudder and occassionally stall. Now after cleaning the IACV it seems to be stuck open at 2000 rpm. After cleaning it was good for 100 miles then went to 2000. So I bought a new IACV and will iinstall it tonight. Hoping it fixes the low idle, high idle, and CEL!!!!

 

Mine did that very briefly. Tightened the bolts and it stopped.

 

Also, I hate to say it, now that you have probably already installed it, but you probably just needed a new gasket and to make sure the donut was facing the same way.

[trxeslr66]

Ok I replaced the IACV and its better. High idle is gone. Low idle is better but I'm not convinced the CEL wont come back on. Its off at the moment and if it stays off I'll consider it fixed but I dont think I'll be so lucky. Any more info?

[Lawsonmh15]

Ok I replaced the IACV and its better. High idle is gone. Low idle is better but I'm not convinced the CEL wont come back on. Its off at the moment and if it stays off I'll consider it fixed but I dont think I'll be so lucky. Any more info?

 

How many miles do you have on your car?

[trxeslr66]

Just under 70k on the car. I havnt updated in a while - problem is still there. It seems the low idle comes after the coolant is up to temp. Still getting the IACV CEL p1507. Need help!!

[Lawsonmh15]

Just under 70k on the car. I havnt updated in a while - problem is still there. It seems the low idle comes after the coolant is up to temp. Still getting the IACV CEL p1507. Need help!!

 

How low is your idle? Mine sticks around 400 Rpm. It does run shi tty before it is warmed up (Runs rich, hard shifting, high idle. Idle only resets after it has reached operating temp. AND I have come to a complete stop for 4-5 seconds.). A While ago I did a coolant flush and put in the Subaru Conditioner. Seemed like my mileage dropped after that. Since it has gotten cold (-14 - 20) the mileage has just crapped out. I need to check my tires, but I just filled up yesterday, have driven 130 miles, and have a little better than half a tank. I am carefull to let it warm up and make the idle drop before I really get moving, so I figured that would at least help until I buy a new IACV. At any rate, let me know if this sounds familiar.

[beezer]

Just under 70k on the car. I havnt updated in a while - problem is still there. It seems the low idle comes after the coolant is up to temp. Still getting the IACV CEL p1507. Need help!!

 

Maybe look at the coolant temp. sensor. They don't always throw a code.

[trxeslr66]

When I start the car it idles high as it is supposed to while warming up. Then after it gets warmed up it drops to anywhere around 3-500 after a few seconds at a stop as you have said. When it gots really below the normal I put the code reader on and it said 250 rpms which means my tach is fairly accurate. I am running out of ideas. Please continue to update here. I will keep my results posted. Any help would be great. Thanks

[Lawsonmh15]

When I start the car it idles high as it is supposed to while warming up. Then after it gets warmed up it drops to anywhere around 3-500 after a few seconds at a stop as you have said. When it gots really below the normal I put the code reader on and it said 250 rpms which means my tach is fairly accurate. I am running out of ideas. Please continue to update here. I will keep my results posted. Any help would be great. Thanks

 

Sounds like it's not the IACV then. If you have a new one, and are having the exact same prob...

 

I have a new thermostat on the recommendation of SubieGal. ($12.95) If that's a no go, I will probably go to the coolant temp sensor. ($30 something)

Glad I haven't dropped $300 on a new IACV. I'll do the thermostat and flush (withOUT) the subaru conditioner and see if that fixes it. If you get tempted to do the coolant temp sensor, it is located under the back of the intake manifold.

 

I'll keep you posted.

 

 

PS

 

How's your mileage???

[trxeslr66]

I replaced the coolant temp sensor and fuel filter (both OEM) this week. The idle might be a tad better. Almost 2 weeks without a CEL. Someone on here asked how low my idle was. On the tach, is is around 500 rpms, sometimes it dips to 400 and sometimes it is higher around 700. 700 is where I think it should be. I'm at 70k now. My mechanic said on Subarus, despite the dealer reccomending 60k, he says wait will 80k to do the timing belt. Possibly the low idle could be coming from the engine being out of timing? My gas mileage varies. While having this problem I got just over 30mpg highway on a trip. As good as 23 city, but my last 2 tanks have been closer to 19. My work is less than a mile away so the car dosnt warm up and would get bad gas mileage because of this. Speaking of gas. My gas gauge is terribly off. It goes almost 1/8 inch above the full line and stays there for at least 50-70 miles. The gas light comes on at 1/4 tank. I filled up yesterday when the needle was at 1/8 of a tank and it took 14.6 gal. When the car was new it filled up directly on the full line and the gas light came on when the needle struck E and a fill up at this point would only take 13 gal. I judge my gas more from how many miles I drive than what the needle says. Anyway this is off topic and less important than the idle problem.

[Lawsonmh15]

I replaced the coolant temp sensor and fuel filter (both OEM) this week. The idle might be a tad better. Almost 2 weeks without a CEL. Someone on here asked how low my idle was. On the tach, is is around 500 rpms, sometimes it dips to 400 and sometimes it is higher around 700. 700 is where I think it should be. I'm at 70k now. My mechanic said on Subarus, despite the dealer reccomending 60k, he says wait will 80k to do the timing belt. Possibly the low idle could be coming from the engine being out of timing? My gas mileage varies. While having this problem I got just over 30mpg highway on a trip. As good as 23 city, but my last 2 tanks have been closer to 19. My work is less than a mile away so the car dosnt warm up and would get bad gas mileage because of this. Speaking of gas. My gas gauge is terribly off. It goes almost 1/8 inch above the full line and stays there for at least 50-70 miles. The gas light comes on at 1/4 tank. I filled up yesterday when the needle was at 1/8 of a tank and it took 14.6 gal. When the car was new it filled up directly on the full line and the gas light came on when the needle struck E and a fill up at this point would only take 13 gal. I judge my gas more from how many miles I drive than what the needle says. Anyway this is off topic and less important than the idle problem.

 

So I guess that it wasn't the coolant temp sensor? Doh. Sometime soon here I need to do the thermostat and then I guess it would be good to see what my timing is looking like.

 

It was weird, the other day I noticed a low whining coming from what sounded like the coil pack. Grabbed the steth. listened, it was. I don't know if these items are related or not, but I considered replacing the coil pack a while back but talked to a tech at a stealership and he said it would have an obvious miss all the time if it were going bad. Weird. I want to know what would happen if any of the windings were shorted to the housing. I want to get to the bottom of this as I feel as though it is causing my shifting to be harder than it should. Also starting to wonder if it could be caused by tightening my throttle cable. Gonna have to do more investigating.

[Lawsonmh15]

Revival.

 

This is STILL driving me nuts. SOMEONE HAS to have had this happen. I'm running out of ideas. I looked at the coil pack today and noticed that 1 and 3 have slight corrosion, but 2 and 4 are clean as can be. It just so happens that the IACV is above cylinders 1 and 3 and I am wondering if this could have anything to do with this.

 

May be way off base, but considering there hasn't been a single person yet to hit the nail on the head, I'll reach for anything. I hate to say it, but I may have to pay a stealership to revoke my driving privileges for a day.

 

I hate that idea since I'm sure that there is no guarantee that their diagnosis will be correct. At any rate.

 

PLEASE HELP.

[beezer]

If there is corrosion on the coil pack then it should probably be replaced.

 

As far as the IAC goes, a slight bobble at idle may be fixed by cleaning it. For a large fluctuation I would say it would have thrown a code.

 

I might check to see if the TPS is set correctly. Maybe O2 sensor. Sorry just guessing.

 

Good Luck, I feel your pain.

 

 

 

Beezer

[Lawsonmh15]

 

I might check to see if the TPS is set correctly. Maybe O2 sensor. Sorry just guessing.

 

Good Luck, I feel your pain.

 

 

 

Beezer

 

If the TPS is off, you will immediately know it. Both o2's are new.

[trxeslr66]

I am posting to update, I have driven nearly 2 months without a problem after replacing the coolant temp sensor and fuel filter. I have no idea which it was that fixed the problem. The new fuel filter is OEM subaru. The old fuel filter was a fram or whatever autozone had, and was only 7 months old. It caused a slight hesitation when I installed it which is wy i decided to go back to OEM 7 months later. My idle still gets low (400-600) but dosnt shudder, shake, stall, or CEL. Since these parts, the car has been running great. I feel your frusteration. If you did the coolant sensor, maybe try the fuel filter? My problem started after a TB cleaning, possibly some gunk got dislodged and ended up clogging the fuel filter?