AURGHH!!! I thought I fixed my stupid Legacy. 1991 2.2L. 189K miles. Starts great. Sounds great cold. Once really warmed up, starts running rough/uneven. New crank position sensor, plugs, wires. Coil specs out okay. Where is the knock sensor? Need to check that. Will recheck cam shaft position sensor next. Am at my wits end with this da-- car! Have already purchased all the parts to do the timing belt job...and lined up a new tranny for the piece of junk, but hate to put any more time, money into the thing if it won't run right. Cant afford to take it to the shop...they'd probably just guess and throw parts at it anyway. Need help!! No pinging. Car has plenty of power. Compression quite good.

The knock sensor is, if you are standing in front of the car, to the right of the throttle body, buried down underneath the intake manifold runners. It is a black circular piece with a 1 wire running from it. I experienced problems around 2500 rpm when my knock sensor was cracked, could be different from car to car though.

 

I would also replace the fuel filter. Another couple thoughts might be the o2 sensor or your air control valve may need cleaning.

 

Good luck. These little things can be very frustrating, I know from experience.

Fuel filter is new. Good brand. Cam and crank position sensors both read .122 to .141 alt volts. Close enough to specs that I doubt thats the problem. Could be attributed to differences in volt meters. Where is the idle air control valve on these cars? Or is it just called an air control valve? No check engine light. No codes as far as I can check in my driveway. PCV valve is new too. There is a sensor of some sort just next to the crankshaft position sensor. It has only one wire going to it and is soaked in oil. Its right next to the EJ22 stamp on the block. What is it? Could be fuel...but don't have a fuel pressure tester. May have to buy one. Idle does not surge. Rough idle problem is intermitant. Need to fix this problem first before dumping any more money into this tank. Checked the throttle body. Looks okay. No heavy carbon. Throttle cables not sticking. Plugs looked pretty normal.

Did a search on the IAC. Found lots of info. Will try cleaning it to see if that helps. Someone mentioned adjusting the IAC upon reinstall. Is there a way that I can mark it so that I don't have to do the adjustment? Tried to find info on adjusting...so far haven't found enough info on this topic...just that it needed adjusting....

Update: oaky went and looked at the car. On the passenger side, there is a cylinder shaped thing with a grey plastic cap and an electical connector. Below it is a 1" rubber hose. It bolts directly onto the throttle body. I am assuming that is the IAC?

Right by the crankshaft sensor is the oil pressure sending unit.

 

Yes that is the IAC. Just mark the the orientation of the top connector, it is held on with 2 small screws. Also remember 2 of the bolts holding it on are longer than the other two, so just remember where they came from.

 

I've heard of the coolant temp. sensor doing strange things without throwing a code. it is located pretty close to the IAC. It is pretty cheap, you could change that with the IAC off it would make it easier.

You don't by chance have slack on your throttle cable do you?

The coolant temp sensor near the IAC, is that the CTS for the guage or the CTS for the coolant fan?

I think the accelerator cable is okay. Problem occurs at idle anyway, not when moving. But will check just in case.

Will need to get an o ring for the oil pressure switch since it is clearly leaking.

I removed the IAC with the engine cold. Too late...read the directions later. The shutter is right about half way open. Does anyone know if this is right amount? The book says to take it off with the engine warmed up...but then its too hot to get in there comfortably. Wish I had read the directions first.

Removed IAC. Looks great. Very little sludge/oil or build up. Doubt its a problem. Do I clean it with carb clean?

I also took mine off with the engine cold and it did'nt seem to do any harm.

You could have a look at my thread «IAC cleaning, asking for help» that is just below yours on the same page to get some more info.

My opinion is that if the shutter cylinder moves freely, you dont have to clean it.

Mine was more like between a third open.

I cleaned mine anyway both with brake cleaner and throttle body cleaner. The results are described in the thread jus mentionned.

There are two easily lost parts still in the throttle body opening where the IAC connects. A round rubberish ring and behind it a round metal disc with openings and a spherical cap soldered to it. Be sure they are still there when you replace the valve body.

Did yours have three bolts holding it like mine or four?

Mine has 4 bolts. I didn't see any small parts at all on the throttle body where it bolts up. Will look again. I hate this car! Desperately want a different subaru but can't find any with good transmissions in my price range near my home. Words cannot describe how sick I am of trying to fix this stupid thing!

Thanks for all the tips though.

Lawsonmh15, why do you ask about slack in throtter cable? Mine has slack in the outer sheild of the cable and it runs rough at idle while in gear. I dont think the inner wire has any slack in it.

Lawsonmh15, why do you ask about slack in throtter cable? Mine has slack in the outer sheild of the cable and it runs rough at idle while in gear. I dont think the inner wire has any slack in it.

 

According to Haynes, the inner wire should have 3/8 to 1/2 inch of deflection near where it connects to the throttle plate. And that's the slack mine has.

Spoke with my subaru parts dealer. They say they sell a lot of coolant temp sensors for idle problems. Thats next.

Midwst,

 

Keep me posted on this problem and especially if you find a solution. I have another thread (named something like: new alternator/rough idle) on seemingly the same problem in my 96 Legacy Outback (EJ22). It has some sort of similar rough/changing idle as well. I noticed mine after I changed the alternator 2 weeks back, but I am not sure if that is the cause. I have also had a temp gauge (or sensor) problem (needle stays close to C always) in the car for the past few years, so I am not sure that woud be the cause of a rough idle in mine.

 

Sweden

Midwst,

I have also had a temp gauge (or sensor) problem (needle stays close to C always) in the car for the past few years, so I am not sure that woud be the cause of a rough idle in mine.

Sweden

 

Since, in your car, the temp gauge is conrolled via the ECU by the same coolant temp sensor that controls part of the fuel trim, I would replace the coolant temp sensor. It's due anyway if it has not been replaced yet and it's a relatively cheap part. Do a search on this board and you'll find info on how to locate it and replace it.

It might be a problem with the gauge itself but it could also be the temp sensor.

Have you had problems starting the car when the engine is hot?

Did you check the knock sensor for cracks?

 

Can you swap spark plug wires? Even if the are new, some of them can be defective.

 

Check out the o2 sensors. As far as I know at start up it is an "open loop", o2 sensor is not taken into account, compared to when driving when it is a "closed loop"

 

Try not too focus too much on one thing, quite often the problem is pretty simple, it just takes a while to track down.