Just curious to see what you all think about the problem I am having with my Subaru.

 

Background

has about 170000 Miles, every 2-3 months throws a missfire for cylinders 1 and 2 but other than that runs fine. Since November it has been throwing a a P1507 code but I really didnt notice any problems with it idling. Later that month (or early December) the car would sometimes die when I put the clutch down, usually exiting the interstate or going down a hill. I could easliy restart it and everything would be fine and dandy. Occasionally however on the restart it would idle REALLY ruff.

 

Well its January now and while the issue used to be maybe once a week it now occurs pretty much daily so I decided to take it in to get it fixed and have the idle sensor replaced as that is what I thought the cause was.

 

When testing it we discovered that the ruff idle it sometimes had was cylinder 1 and 2 just not running (Removed spark wires for cylinder 1 and 2 didnt change how the engine performed)... We replaced the distributor coil and while I drove the car it seemed to sometimes idle low but didnt die (drove it for about a week) after replacing that coil. The ohms on the coil, and spark wires seemed fine. So we replaced the idle sensor but it still throws the code and occasionally on restarts cylinder 1 and 2 stop working (but if you restart it it works just fine). Engine compression is good and the air flow sensor is also working fine.

 

Sooooo so far we have replaced the distributor coil, idle sensor, and are now looking at possibly swapping the computer (ECM?) of the subaru to see if that helps. So far I have not been charged for parts just labor as we are experimenting.

 

Soo if you got this far reading that what do you think? There appears to be a forum posting if you google the error code about replacing a the neutral switch? Dont think that relates to this but what do I know.

Spark plug wires are notorious for causing misfires on these. If the plugs and wires haven't been changed recently do that. Get NGK parts or Subaru only.

I don't see the term "Spark Plug" anywhere. Replace them and the wires and lest get a clean baseline. Replace the wires as they are old and can "look fine" but be worn and useless.

Spark Plugs replaced a year ago, but they are cheap and maybe replacing them again is a good idea. The wires have not been replaced since I have owned the car (4 years?) so I can replace those also. Would that make the car throw that idle error?

Get the proper plugs for the car nothing fancy. Use Subaru OE wires.

 

It can throw the codes, and yes lack of a tuneup can make the car run like crap.

 

Have you swapped the coils around to see if the problem moves, if it doesnt it is not the coils.

 

How old is the timing belt?

Timing belt was replaced last year. When you say coil are we talking about the thing on the top of the engine were the 4 spark plug wires are connected to? If so ya we swapped it and it seemed to me as it wasnt dieing as much but it did die for the mechanic.

 

Side note the car doesnt really idle ruff it kinda just dies like it was falling asleep... It only ruff on restart sometimes and that appears when Cylinder 1 and 2 are not running. But it is not throwing any codes for that.

Is it throwing any codes.

 

Was everything replaced with the timing belts.

 

Very odd to have 1-2 go bad as they are on opposite sides of the engines.

 

Yes the two black boxes with wires are the two coils.

Only codes is the P1507 Error for the Idle and every couple of months a Cylinder 1 and 2 Misfire. And I know for sure I swapped the belt for the timing belt but I will have to check on everything else.

I am wondering how the ground is at the coils. Do me a favor, spray water on the coil (this can be done with a warm engine if it is freezing outside) in the evening and look for sparklies.

1507 is your idle air control valve.

Needs a thorough cleaning.

Do search here and you will find things to look for, how to clean and how to deal with the brass screws that hold it on

Generally you will have a wavering idle, up and down after a few minutes of running.

 

O.

Replaced the valve and cleaned it all. Still throwing the code and it still isnt idling right.

Are all the hoses attached to the air intake?

 

I am begining to think you may need a compression test to see what is going on.

 

When and how did this first start

When you cleaned it, did you remove the plastic electrical housing?

 

If not, that is where the magnetic portion of the wheel is hidden that controls the air.

 

It has to rotate freely.

 

O.

Edited January 21, 201214 yr by ocei77

Ok swapped out the spark wires and checked the plugs. Plugs are good. Swapped out the ECM and it the gremlin is still there. Going to try swapping out that idle sensor next week.

Idle issue fixed... Two weeks no problems. I will post a reply if that changes.

 

SOOOOO for those with the P1507 Error and you have a 99 Subaru Outback and replacing the idle valve/sensor doesnt fix it, swap the neutral switch.

Edited February 21, 201214 yr by I)arkZrobe

I am confused. Idle air control valve or idle air control sensor?

I'm trying to understand how this all works and the terms used mean different things.

My old ea82s all had idle air control solenoids if my memory is right.

Same on my wife's 2000 Forester? 5 speed manual transmission.

 

Months ago it was idling near 300 rpm (no continuous cel) and not knowing what I was doing, I adjusted the positioning of the throttle position sensor (it is slotted) and the idle came up nicely to about 800.

She was temporarily happy. After a few days the idle again returned to very low, both hot and cold and frequently stalling.

This weekend I tried the same thing and again the idle speed was set at 800ish.

And after a few days it dropped down again.

Does the ecu relearn the relation between the new tps feedback and idle speed and then compensate to a lower idle? Possibly based on some other faulty sensor or solenoid?

Or back to the top of my post. Try changing the idle sensor or solenoid or whatever it is called?

rick

w mi

I fixed my post. We swapped the valve and that didnt fix it. The fix was actually replacing the completely unrelated neutral switch. Seems like its a issue on some of the manual transmissions of that generation. Symptoms include P1507 Error, poor idling and when the engine dies and you restart it a huge loss of power (Limp Mode), restarting the car returns it to normal. I hope that clears things up. Sorry again for posting about the wrong part switch.