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1998 Subaru Legacy Outback
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6 Posts
Discussion Starter #1
My battery was low, I unconnected it and cleaned it with baking soda to eliminate the corrosion. After reconnecting the battery, the idle is racing and won't go down. It's at about 2k. I've read about how the computer has to relearn how to idle, and I've done what those people suggest, i.e. let it idle for 20 minutes, go for a short drive, try to disconnect and reconnect the battery a second time in case the computer had a problematic boot the first time around.

None of these help though. Any thoughts? Perhaps I just whacked something while getting battery in and out of the vehicle?

I had the guy at autozone pull the codes; there were many. It runs pretty good other than the idle . . .
 

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2011 Tacoma TRD Sport Double Cab Long Box
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2,893 Posts
What were the codes? That would certainly be helpful.

Out of curiosity, can you check the voltage of the battery when it's running and when it's not? You say it was low...what do you mean? Batteries that are going bad can do some funny things.
 

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1998 Subaru Legacy Outback
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6 Posts
Discussion Starter #3
The battery was corroded and was barely able to get the car started a couple of times. After I cleaned it, it's fine. I have a very short commute and I think it's not that good on the battery since it doesn't get much charging time and has to do lots of starts and stops.

I'll check the voltage, and post some codes when I get home tonight.
 

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18,722 Posts
I've seen that happen on an a neighbor's 98 after the battery was disconnected and then reconnected. Engine didn't run properly, and lots (!) of trouble codes. Car was flat-bedded to dealer. Mechanic used the Subaru code reader (SSMIII) to clear the codes, and all was back to normal. The codes were caused by some sort of software glitch when the battery was disconnected and reconnected, and not due to actual engine problems. They included codes that would normally put the engine into "failsafe" mode. By clearing them using the SSMIII (not by disconnecting the battery), the engine control module starts back with it's defaults, instead of with the codes already triggered, and goes from there. Not sure if this is the same with your car, but perhaps worth trying.
 

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1998 Subaru Legacy Outback
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6 Posts
Discussion Starter #6
Battery reads 12 volts, 14 volts running, and 9 volts when cranking. All good, right? It's an older battery, but seems fine.

Codes (lots of codes):

P0101
P0301
P0302
P0341
P0601
P1100
P1107
P1120
P1141
 

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18,722 Posts
Battery, when fully charged, should be at around 12.7 Volts. 12.0 is usually a partially discharged battery. But the 14 V running is good. It's possible the battery has a bad cell, and can't be charged fully, or perhaps, as you noted, it never has a chance to be fully charged given the short commutes. It might be best to use a charger to get it up to full charge, or at least see if it can be charged.

The range of different, and seemingly unrelated, codes suggests they aren't real but are affecting the way the engine is controlled. They should be cleared, and then see what happens. If there is a real fault, one or more will come back. Otherwise the engine will probably settle down to normal operation.

P0101 Mass Air Flow (MAF) Circuit Range/Performance Problem
P0301 Cylinder #1 Misfire Detected
P0302 Cylinder #2 Misfire Detected
P0341 Camshaft Position Sensor Circuit Range/Performance
P0601 Internal Control Module Memory Check Sum Error
P1100 Starter Switch Circuit Malfunction
P1107 Secondary air injection (AIR) diagnosis solenoid - circuit malfunction
P1120 Starter Switch High Input
P1141 Mass Air Flow Sensor Circuit High Input

Although I imagine the code readers that Autozone uses can clear codes, I understand some stores won't clear codes on request. But maybe your local one will. Otherwise, many reasonable cost OBD-II code readers can clear codes and are often on sale at stores and on sites such as eBay.
 

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2014 OBW 3.6R Limited, 1997 OBW 2.5L Auto (sold, but not forgotten), and 1991 Ford F150
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1,525 Posts
Probably a long shot, but this may be the "green connector" problem ...

There are green connectors under the dash on the driver's side. They are only supposed to be connected for testing/diagnosis purposes and should be apart for normal operation. One symptom of connecting them is a check engine light with multiple unrelated codes when read. Another symptom is the cooling fans running way more than they normally do and all the solenoids clicking. Don't know about the effect on idling, though.

Something to be aware of and check.

 

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01 VDC, 05 R Sedan, 06 BAJA EJ257
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15,483 Posts
Voltage spike.

Disconnect the battery, both cables, and join the pos and neg cables together.

Get a new battery.
 

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1998 Subaru Legacy Outback
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6 Posts
Discussion Starter #10
Battery, when fully charged, should be at around 12.7 Volts. 12.0 is usually a partially discharged battery. But the 14 V running is good. It's possible the battery has a bad cell, and can't be charged fully, or perhaps, as you noted, it never has a chance to be fully charged given the short commutes. It might be best to use a charger to get it up to full charge, or at least see if it can be charged.
My multimeter is an small analog and I have to use the 50V setting, so I'm not sure my accuracy is good enough for differentiating between 12.7 and 12. As long as my car is turning over good this time of year, I can't see any reason to replace it. I guess I can have it tested at the battery shop to see.

The range of different, and seemingly unrelated, codes suggests they aren't real but are affecting the way the engine is controlled. They should be cleared, and then see what happens. If there is a real fault, one or more will come back. Otherwise the engine will probably settle down to normal operation.
Excellent. Seems to have worked like a charm. Thanks man.
 

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Good news. Thanks for the update.

Did Autozone clear the codes for you, and if not, how did you clear them?

Incidentally, your analog meter is fine for general work, but perhaps consider adding a digital multi-meter. They're relatively inexpensive, and will usually have the appropriate ranges for automotive work, including a low Voltage range that can be used to detect bad grounds in the charging system. Well worth it if you're going to be maintaining your car yourself.
 

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1998 Subaru Legacy Outback
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Discussion Starter #12
Incidentally, your analog meter is fine for general work, but perhaps consider adding a digital multi-meter. They're relatively inexpensive, and will usually have the appropriate ranges for automotive work, including a low Voltage range that can be used to detect bad grounds in the charging system. Well worth it if you're going to be maintaining your car yourself.
I'll get a digital. High mileage subaru so I'm expecting to be doing some work. As for the code reader, the guy at autozone said his wouldn't clear codes but I went to NAPA and theirs would.
 

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2011 Tacoma TRD Sport Double Cab Long Box
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I'll get a digital. High mileage subaru so I'm expecting to be doing some work. As for the code reader, the guy at autozone said his wouldn't clear codes but I went to NAPA and theirs would.
I'd look at getting a code reader, too. I found one on Ebay a while back for about $50. It works well and will erase codes without a problem. Well worth the money.
 
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