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Idle issue '95 Legacy Wag


95Subi

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RE-POSTED for easier understanding. Keep in mind, Knock sensor, MAF sensor, O2 sensor and IAC have been replaced...IAC, I have tried FOUR different ones, even though from different cars, still same issue. I have tested the plug going to the IAC. When using my advanced Voltage Meter, I tested Voltage from BLACK wire to WHITE wire on plug, getting .8 volts. When testing the YELLOW/RED STRIPE wire to ground, with key on, I am getting 11.75 volts, which is more than the ten I need, but not sure what sort of reading I am supposed to get from either BLACK and WHITE wires. (Need help there please) Resistance from terminal 1 and 2 (on the IAC itself) and 2 and 3, resistance is supposed to be 7.3-13 Ohms, I am pushing a perfect and steady 8.7 on each terminal. When testing terminal 1 and 3, I get 17.5, which I am gonna assume doesn't mean anything bad, cause I am skipping an entire terminal. (TESTS SEEM TO BE CHECKING OUT, but still kicks on check light, reason being "IAC"....

 

Hey there, the nickname is Stich and I am new to the forums.

 

This is a 1995 Subie Legacy L Wagon with just over 100,000 miles and a 2.2L motor. When I am stopped for a light or leave it running in Park, the engine seems to skip and the RPM needle will drop a notch. Then just when you think it will stall, the engine "catches" itself, the needle returns to its former position and the motor runs smoothly for about 15 seconds. Then the process starts all over again. It happens whether the A/C is on or off.

 

Nothing happens when driving along. In fact, it is very smooth and an absolute pleasure to drive. A mechanic spent hours checking everything and-you guessed it-said there is nothing wrong. He even left it running for 1/2 hour with the A/C on as well as the radio and claims it didn't happen. He even went on the internet to ask other mechanics to no avail.

 

I was told a little movement in the RPM indicator is normal and I'm OK with that. But the car skips or misses and then jumps backs up, sometimes very noticeably. It can get to the point where a vibration is passed through to the driver.

 

I feel that this is something minor that is escaping notice. Otherwise, I couldn't ask for a better auto, but I also cannot live with this problem since I'm worried about taking it for a drive of 50 miles or so. My husband won't take it to work (yes, he noticed the problem also) since he comes home at night and has to go through the rough part of a town and is afraid that it will eventually stall and leave stranded in a dicey area.

 

So I thought I would throw the question out there in the hopes that someone may have some insight or had same problem.

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This problem started after replacing IAC and MAF sensor, I broke almost every vacuum line that went to the PCV valve and Crank Case lol...

 

Tomorrow I am gonna double check the new vacuum hoses that run to the IAC, PCV and air intake housing...I am thinking, find a better fitting and re-do the lines and use new hose clamps. Maybe I have a leak in that system, which would of course kick on the CHK eng. light for IAC

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Double check the large hose that comes from the crankcase and splits off to the IAC, PCV and intake. This tube gets hard and brittle with age and maybe has a crack in it.

 

O.

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Thank you for the reply Osei. I have been stuck working the last couple days, But I will check that. I know there is a small chunk missing where it cracked when I first replaced the thick hose, but couldn't find a parts store that had a big enough hose tha twasn't TOO big....So I tried to fit it as best I could. I realized that after looking over the vacuum lines at work.
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  • 2 weeks later...

No luck with the Temp sensor either..In FACT, now I have the problem of maybe damaging the sensor plug, cause now my temp gauge doesn't work, plus I realized my engine fans NEVER kick in, but still having that idle issue....

 

I dunno, I'm about ready to give up. This is REALLY ANNOYING ME!

 

I have tested the fans, they do work...Relay is new, fuse is still good...Could the issue with my engine fans not turning on be causing this erratic idle??? Like stated, the car drives like a dream, but idles perfect for a second, then starts bouncing from 700 - 300, then back...ONLY WHEN WARM

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Are you sure that the CEL bulb is working? Older Subies tend to have a lot of burned out indicators bulbs. If so, the CEL could be 'on' but not showing. Also, have you hooked up an OBD scanner and checked for any codes? Apologize if this has been covered or not applicable ... just tryng to help you out. Sounds like a very frustrating situation.

 

Good luck,

Hem

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Ok, the gauge wire is a separate one wire connector. Did you remove and replace the correct one? The CTS is screwed into the back of the crossoverpipe near the iacv and has a two plug connector.

Are you getting any codes for EGR?

I had a similar issue with erratic warm idle on my 96 OB and finally traced it to a clogged line from the egr valve to the exh. manifold AND a bad egr solenoid valve.

You can check the solenoid by mating the green connectors under driver side and turning the key to the on position. All your solenoids will click and the fans will cycle. Listen to the egr and verify operation. You may have to remove it from the manifold first to really hear or feel it working.

Don't forget to unplug the connectors before continuing.

Did you check the IAC valave itself?

 

O.

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Ok, the gauge wire is a separate one wire connector. Did you remove and replace the correct one? The CTS is screwed into the back of the crossoverpipe near the iacv and has a two plug connector.

Are you getting any codes for EGR?

I had a similar issue with erratic warm idle on my 96 OB and finally traced it to a clogged line from the egr valve to the exh. manifold AND a bad egr solenoid valve.

You can check the solenoid by mating the green connectors under driver side and turning the key to the on position. All your solenoids will click and the fans will cycle. Listen to the egr and verify operation. You may have to remove it from the manifold first to really hear or feel it working.

Don't forget to unplug the connectors before continuing.

Did you check the IAC valave itself?

 

O.

 

Yes. As stated earlier, I checked the connector, power wire getting 11.96 volts to sensor, tested 5 different sensors. (Know a friend at the junkyard, got 4 for 15 dollars) And they ALL tested the EXACT same voltage when plugged in and resistance and the shutter opened and closed whether power was applied or not. So they seemed to check out.

 

CEL is illuminated, but ONLY reads Oxygen sensor. Car will run perfect from time to time, but only for a couple of seconds after coming to complete stop. Then it can't hold a steady idle.

 

This issue ONLY happens when WARM. After doing more research, and even testing for vacuum leaks, everything seems perfect, no issues....

 

I was able to get the engine fans to work. I manually hooked them to a fuse that had power only when key was in "acc" position. That's done. ***

 

Now after researching more, a young lady was having same issue with her Stick Wagon, replaced the TPS and said it fixed her idle issue. After thinking about it, The TPS may NOT be completely shot, so it's not kicking on the eng. light or as the person before you stated, it may be malfunctioning and not giving a proper reading.

 

A dying TPS WOULD account for my idle issue, would cause poor idle, loping idle when warm, and even keep the rpms temporarily at around 1,200 after putting clutch in and coming to a stop. TPS would cause a LOT of running issues, but if just malfunctioning, could still allow the car to drive perfect.

 

 

 

AS FOR THE COOLANT SENSOR: I replaced the correct one, the sensor fit perfect. In my car, the coolant temp sits under the coolant hose going to the IAC and is threaded horizontally. After replacing that sensor, now my coolant gauge does not work. :eek:

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And just to recap;

 

Car drives GREAT! Like a new car. Holds a steady speed, but will not idle properly when warm. When COLD, she idles perfect until JUST at the point of warming up, the idle will go from 700 up to 1000 and back to 700 a couple times.

 

But CEL does NOT illuminate IAC anymore, JUST bank 1 sensor TWO oxygen sensor (The one that is missing.

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Got coolant sensor to work, plug was cracked and not in properly. Replaced tips sensor and still having the idle issue.

 

Wondering if it could for some reason be timing related...but if timing related, shouldn't the idle consistantly act like this without running normal from time to time?

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Does not sound like a timing issue.

I assume you have EGR. If so, did you check operation of that solenoid and the lines that lead to it?

Specifically the small metal tube that comes from the manifold? Can you blow though it?

Checked the BPT?

Here is ref to FSM for future use.

http://www.main.experiencetherave.com/subaru_manual_scans/

 

I know its frustrating.

 

Just reread your original post. Since all started with a change of IAC and Maf, although voltages show IAC are correct, is it operating correctly?

The wheel in the IAC should turn freely. If there is a carbon buildup, it won't.

MAF clean?

 

 

O.

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Does not sound like a timing issue.

I assume you have EGR. If so, did you check operation of that solenoid and the lines that lead to it?

Specifically the small metal tube that comes from the manifold? Can you blow though it?

Checked the BPT?

Here is ref to FSM for future use.

http://www.main.experiencetherave.com/subaru_manual_scans/

 

I know its frustrating.

 

Just reread your original post. Since all started with a change of IAC and Maf, although voltages show IAC are correct, is it operating correctly?

The wheel in the IAC should turn freely. If there is a carbon buildup, it won't.

MAF clean?

 

 

O.

 

To your reply, I have put 3 different iac s in car and no difference. When I unplug iac when warm, car consistantly runs like how I described, then when plugged back in, idle jumps up to normal but craps again. Omg!!!! Problem solved....I think. I had issues losing all power while driving and was maf. Got one from eBay and no more dying while driving...but idle issue appeared. I plugged in old maf and car idles a little rough but no more bogging and jump idle

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