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Discussion Starter · #1 · (Edited)
98 outback 2.5 intermittent lope at idle(Updated info!)

Hey guys,

So I just got done with a head/timing belt repair on my 98 Legacy Outback. I had both heads rebuilt due to a burnt exhaust valve, also replaced timing belt/pulleys, water pump, thermostat, spark plugs, wires and PCV valve. I got everything back together and checked the timing about 10 times to make sure it was right. After all of this, the car seems to run fine at any operating speed except idling.
So when stopped at a stop light/sign the car will idle fine and then will occasionally lope. It feels like the the rpm's drop to around 200 as if the car is going to quit, yet the rpm gauge really don't move. It only happens for a split second then the car starts to idle fine again. There is no rhythm to it, it is very intermittent, though it does it every time I stop. It just does it more sometimes and less at others. It is also much worse when the car is in drive vs. park.
There is no check engine light on, and I have tried to find a vacuum leak with no avail.

Any help would be appreciated,

Dan
 

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Check your Crankshaft and Camshaft sensor plugs to be sure they are tight and the wires going in to the plug are not pulled out.

Check the coil, its plug and also the wires again. You may have a wire arcing or loose connection.

Check that all the ground lugs you took loose are clean and tight.
 

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Discussion Starter · #3 ·
Checked all of the electrical stuff and double checked the vacuum lines. Still have the same problem. Could the timing be one tooth off and cause symptoms like this?

-Also I noticed that it only does this when the car is warm. It runs perfect when the car is cold.
 

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98 obw 2.5dohc..auto & 99 obw 2.5dohc...auto
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Checked all of the electrical stuff and double checked the vacuum lines. Still have the same problem. Could the timing be one tooth off and cause symptoms like this?

-Also I noticed that it only does this when the car is warm. It runs perfect when the car is cold.
Same problem on my 99....help?
 

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When the car is cold, the idle and timing are advanced to warm the engine. As the engine temperature comes up, the idle and timing are reduced. If its not "hunting" for idle when its cold or hard to start, I don't think the timing belt would be off. It is possible for one cam to be off one tooth and the engine run, only it would run uneven through all rpm ranges until it reached higher rpm over 3k. If the crank is off one tooth, it would lope, but also start hard depending on which way it was off.

You could pull the cover and check it. All you need to do is make sure the hash marks line up with the timing marks on the head and rear cover while the crank lines up with the mark on the block. Also double check the tensioner is actually putting tension on the belt.
 

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Discussion Starter · #6 ·
So it seems to be getting worse and I now can feel it when driving. Though it still only does it when it is warm. I have only put 100 miles on it since doing all the work. The car starts very easily. I will check the timing this weekend.:mad:
 

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Crazy thought occurred to me yesterday....have you checked the gasket between the headers and the midpipe? You know, the flat one that tends to leak? I know mine is leaking for sure and I think it's interfering with the 1st O2 sensor causing it to correct for too much air and leaning the mixture yadda yadda yadda. Mine's been getting worse as well. I'm going to check mine soon so thought I would share...
 

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Crazy thought occurred to me yesterday....have you checked the gasket between the headers and the midpipe? You know, the flat one that tends to leak? I know mine is leaking for sure and I think it's interfering with the 1st O2 sensor causing it to correct for too much air and leaning the mixture yadda yadda yadda. Mine's been getting worse as well. I'm going to check mine soon so thought I would share...
Actually its the other way around. An exhaust leak in front of the front sensor will cause a rich condition because there would be more oxygen sucked into the pipe and the computer will add fuel to match what the O2 is sending assuming that the engine is running lean. When it adds too much fuel without a timing correction, it causes a loss of torque and power. The LTFT on the car would be high in this case.
 

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I had something similar with mine, but also threw a P0304 CEL. Mine would do it at idle, but was fine when driving. My cats and o2's were replaced along with my plugs and wires, problem gone. Might not be the issue, but I would say find a shop that can test your cats and o2 to rule that out. Look on the intake end for issues too, couldn't hurt.
 

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Actually its the other way around. An exhaust leak in front of the front sensor will cause a rich condition because there would be more oxygen sucked into the pipe and the computer will add fuel to match what the O2 is sending assuming that the engine is running lean. When it adds too much fuel without a timing correction, it causes a loss of torque and power. The LTFT on the car would be high in this case.
That's what I meant :) my 02 sensor is reading rich and compensating by leaning the mixture, causing a lope while at idle.

Here's my hypothesis. Car is driving down the road with no issues, but at idle there is a constant correction in which the mixture is leaned. Well, based on Bernoulli's Principle of airflow, if there is an exhaust leak, it makes sense why it only occurs at idle. The speed of the air passing through the exhaust pipe creates a pressure differential in the pipe. There is a lower pressure along the inner walls of the pipe than in the center of the pipe. Thus at idle, the outside pressure of the air is higher than that inside the pipe and air is pulled into the Pipe to compensate; the mixture is seen as Rich and adjusted. When driving at any speed however, the pressure inside the pipe is greater than the low pressure system that surrounds the car and the exhaust gas is pushed out of the leak instead.

Just a hypothesis....;)
 

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Discussion Starter · #12 ·
Ok, So I checked the timing(took off the front covers) and the timing looks dead on to me. I re-checked the spark plug gap and I went out there at night in my dark garage and sprayed water on the coil and wires and can't find any that are arcing out.

So, while checking everything I had to drive the car and not go by my wives account. The car does this when it is cold, it just gets worse as it warms up. It is also worse when stopped with the brake on vs. stopped when in park. You can feel the "miss" or "lope" whatever it is at all driving speeds, but it is very intermittent and often time you don't feel it at all. Along with this there is an occasional hesitation when accelerating from a stop. Again this is only some of the time, and not the norm. The car seems to have plenty of power.

The check engine light did come on so I will scan the car and get the codes and post them as soon as I have time to scan it. I also removed the IAC and cleaned it, but this did not seem to help, but figured it has never been done so it was a good time to check and clean it.

Thank for you help
 

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Ok, So I checked the timing(took off the front covers) and the timing looks dead on to me. I re-checked the spark plug gap and I went out there at night in my dark garage and sprayed water on the coil and wires and can't find any that are arcing out.

So, while checking everything I had to drive the car and not go by my wives account. The car does this when it is cold, it just gets worse as it warms up. It is also worse when stopped with the brake on vs. stopped when in park. You can feel the "miss" or "lope" whatever it is at all driving speeds, but it is very intermittent and often time you don't feel it at all. Along with this there is an occasional hesitation when accelerating from a stop. Again this is only some of the time, and not the norm. The car seems to have plenty of power.

The check engine light did come on so I will scan the car and get the codes and post them as soon as I have time to scan it. I also removed the IAC and cleaned it, but this did not seem to help, but figured it has never been done so it was a good time to check and clean it.

Thank for you help
I'm having the EXACT same issue with my 99. The past couple of days have been a little warmer (upper 40's and 50's), which seems to have helped, but I also notice that when I step on the brake harder it seems to be less prevalent. I dunno if it's transferring the shake to the tires and dispersing it better or what. However, I seriously think it has something to do with that exhaust gasket right behind the headers....could be wrong. I just re-timed mine, replaced the HG, all the accessible stuff, pcv, etc. I have spent over 1100 just in parts. (I buy quality stuff...) Still at a loss for why it does it though. Averaging 21-22 around town and 26-27 on the highway with 6month old Michelins.

My other idea is a slow vac leak somewhere that only happens in low-vac situations. Egr? Leaky hoses? It drives me nuts!
 

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Sarged 76, Brake Booster is leaking.

ScoobieTheSubie, yours may be running rich and applying the brake is allowing for more air.
 

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Scoobythesubbie I have the same issue although I'd describe it more like humming a demented tune than a lope as it sounds more random. Yes it is running rich, but why?
Can you see your tachometer move up and down? Mine does.
 

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Scoobythesubbie I have the same issue although I'd describe it more like humming a demented tune than a lope as it sounds more random. Yes it is running rich, but why?
Can you see your tachometer move up and down? Mine does.
That is where data is needed from the car in order to determine the source of the performance loss. The list of possibilities is not large and it is possible to check each indivisual sensor and actuator separately, but scan tool data is quicker and easier. Beats crawling under a car to get to a plug or having to remove parts to get a proper connection with a DVOM.

Rich is too much fuel. It is caused by a mechanical failure or improper data transfer to the ECM that throws the math off from what is actually happening.

MAF, MAP, TPS, Front O2, spark plugs, ignition cables, injectors or type of fuel. That's where you start.
 

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Yes the list of systems you mentioned are on the invoice I paid Wentworth Subaru in Portland Oregon to check and or replace (for $1585) in 2011 just nine days before it failed smog last time.
 

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Discussion Starter · #18 ·
Update!

Ok, so here is an update on my car....

-The car has a code 0304 cylinder 4 misfire. As I said earlier this car did have a burnt valve on cylinder 4. So both heads have been rebuilt, new timing belt and pulleys, new waterpump, new thermostat, new plugs and new wires and of course new gaskets and seals on the top end.
-The car has gotten progressively worse and it now really feels like a misfire. It does it all the time, though it does smooth out as I accelerate and does still seem to run much better when the car is cold.
-I checked the compression and it has 150 +/- 5 psi in all cylinders.
-I switched the spark plug wires on the 2 and 4 cylinder, but this did not change how the car is running.
-I pulled the wire off of the #4 terminal of the coil pack is firing, but not sure if it could have a weak spark and this could be the problem?

Any other suggestions?

Dan
 

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Discussion Starter · #19 ·
More info...
So I re-checked the timing today and the timing is dead on.
I also pulled off the 2-4 valve cover to recheck valve clearance. Here are the specs....
Cylinder #2 - Front intake: .0065in(.165mm) Rear intake: .0065in(.165mm)
Front exhaust: .0085in(.261mm) Rear exhaust: .010in(.250mm)
Cylinder #4 - Front intake: .0075in(.190mm) Rear Intake: .0075in(.190mm)
Front exhaust: .0085in(.261mm) Rear exhaust: .010in(.250mm)

For Cylinder # 2 intake, front exhaust and cylinder #4 front exhaust, should I readjust them to be closer to spec or it .015in(.035mm) close enough? From what I find they should be within .0008in(.02mm), but I am very close to that. It is just a pain to get the shims out without a tool and without removing the camshafts, so I would rather not. I also don't want to burn a valve.

Thanks again for you help
 

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Any update regarding this idle issue? The lope pn my 97 has become worse. It makes the in town gas mileage 17 mpg, while the highway is 27 mpg.
 
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