Subaru Outback Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hi All,

First off, I have been reading & researching this issue for months on end spending countless hours and late nights reading and have still been unable to solve my problem.

I have a 98 Legacy Outback EJ25, Manual Trans, 138,000 Miles. I bought it from the original owner about 2 years ago and it was running great until last year.

It starts just fine and idles smoothly when cold. It also drives good, great in fact when the engine is still cold - it accelerates smoothly and with plenty of power, but the second the temp gauge starts to move it begins idling rough, missing and loping and now it will even stall out and become very difficult to restart.

The fact that it ONLY happens after the engine has warmed up indicates to me that it is likely sensor/ecu related and not something mechanical. If it were mechanical (Timing belt off a tooth, injectors, valves, etc) then the problem would occur regardless of engine temperature, right?

THE ENGINE HAS NEVER THROWN A CODE, OTHER THAN MISFIRE DUE TO EXTREMELY ROUGH IDLE

I really love this car and want to keep it, but I have thrown a ton of money (AND TIME!) into it chasing down this problem. The following is a list of items I have replaced in order:

MAF (used unit, tested good)
IAC (used unit, tested good)
Knock Sensor (temporarily replaced with fixed resistor to rule out this sensor, will replace with new sensor soon)
Plugs (New, OEM)
Wires (New, OEM)
TPS (New, OEM)
Front o2 (New, OEM)
Fuel Filter (New, OEM)
Air Filter (New, OEM)
PCV (New, OEM)
Checked all vacuum lines (replaced a few hard vac lines but found no leaks)
Checked all electrical connections & cleaned with CRC contact cleaner

Last year in the process of chasing down the problem I got the dreaded "overheat & HCs in coolant indicative of internal HG failure".

I pulled the engine and had the block & heads resurfaced by a respectable machine shop in preparation for new MLS gaskets and while the engine was out I bit the bullet and replaced:

HG (OEM, MLS)
Timing belt & all related pulleys & tensioner (New, OEM)
Clutch Master Cyl
Clutch Slave Cyl
Oil Spearator Plate (New, OEM)
Flywheel resurfaced
H2O Pump (New, OEM)
Oil Pump (New, OEM)
Radiator & Hoses (New, OEM)
Thermostat (New, OEM)
All New seals throughout

It took a long time as I gathered the resources and found time to complete the repairs because I had a new baby, and I have finally got it all back up & running.....and the problem remains!

This car is essentially ALL NEW parts! Only things that I can think of left to replace are coil, ignition control module, Crank sensor, cam sensor & Coolant temp sensor, ECU....have I missed anything?

My family and I are really struggling in this tough economy and I don't want to keep throwing money at this stupid car which is essentially my backup/camping vehicle, not my daily driver. I don't want to get rid of it because I have invested A LOT of blood, sweat & MONEY in it.
I am an accomplished mechanic having rebuilt literally dozens of engines from practically every maker, but this is my 1st Subaru.

Any help or past experiences would be helpful, thank you so much for taking time to read and lend a hand!
 

·
Premium Member
2001 VDC/SC One of a Kind
Joined
·
12,847 Posts
Fuel/Air/Fire/Ignition in the right mix and correct order.

Somewhere along the lines when the ECM switches its fuel map after it warms up, you are losing the mix. It is either the fuel you use, a vacuum leak you haven't found, a bad ground or battery (or both), loose connection at a sensor or fuel pump.

Vacuum leaks should have been taken care of when the engine was overhauled.

Fuel is a tricky thing. If you buy cheap, you get cheap. If you buy a major brand gas, or a station that has a major brand label/sign, and the station doesn't see a lot of fuel traffic, water can be an issue, or the settlement of alcohol on the base of the tank is finding its way in to your tank.

Bad grounding and/or conductivity. Electricity is the heart of everything electronic on the car. Sensors, actuators and the computers. If the systems do not have enough electrical flow for use, you get a dumbed down car. Think in relationship to a laptop or cell phone with a low battery, it slows down. Same with the ECM. And if the electrical flow is low, solenoids and switches will either work poorly or not at all. Start with the battery and check ampere output and work outward from it.

Corrosion is resistance. loose pins at the plugs mean sporadic outputs or operation. Check them.

Fuel pump could be running great and supplying sufficient fuel a for cold running engine and then as it heats up, with the engine, expansion of the metals in the pump or module reduces the pump output. Check the fuel pressure cold, then after the engine warms up and acts up.
 

·
Registered
Onyx, 2008 LL Bean 3.0R and 2017 Honda Civic Hatchback Sport Touring
Joined
·
4,112 Posts
Rotate the tires. Just kidding. I can totally relate to your frustration. I inherited my OBW and it needed a lot of work - just put in a used transmission for example. Somewhere during the process of fixing all the little things and chasing down more complex things - had a relentless steering wheel shimmy - I crossed that line where it made more sense to keep investing in (throwing money at) the car because I would never get it back. You are not alone brother. When she runs well everything is great.

I have the utmost respect and admiration for Cardoc. But I also love to try and second guess the experts. If it was not for the it only happens when it warms-up part, I would put money on the coil. Even then, there could be a hairline fracture or short that is exacerbated when the engine bay gets hot. So, the coil?
 

·
Registered
2017 Outback 3.6 Touring, which replaced '05 Outback XT
Joined
·
762 Posts
I don't know if this applies to your model, but some of the temperature sensors are dual units. Half of it controls the gauge, the other half tells the ECM how warm the engine is. If the sensor is broken, the ECM would think the engine is cold when it isn't, but the gauge could still work.
 

·
Registered
Joined
·
2 Posts
Discussion Starter #6
Hey Guys,

Thanks for the relpies, any help is very much appreciated!

cardoc - I have been short on time & cash as of late, but when I find the time I will go thru with my multimeter and test all my connections for resistance & output.

I didn't think of the battery cables/grounds....they do seem a bit stiff & probably need replacing anyways.

DavidPeab - I have definitely crossed the threshold of time/money invested to money returned if I sell it...plus I really do love the car! Most definitely the easiest and most enjoyable engine I have worked on to date - everything just seems to be put together so intuitively. Practically no need for 'Special Service Tools', just a good basic tool kit & torque wrench and you're good to go!

I will keep chugging away until I figure it out! I know I can get another 100,000 miles out of it if can just get it to run properly.

Thanks cardoc, DavidPeab & Radar for the replies, this site has been like a bible to me for past couple years!
 

·
Registered
97 Outback 230000
Joined
·
1,134 Posts
I don't have any advice but I do have empathy for your situation. Once you are invested then you don't want to give up. Without planning to you have ended up with an expensive hobby. It could be worse, you could be an underwater photographer with a gambling addiction. Hope you find the cause of the failure to run properly. This site is the best.
 

·
Registered
95 Legacy L Wagon 2.2 4AT
Joined
·
14 Posts
My first reaction to this was coil too esp when i saw it wasnt on the list of things checked. I had a car do that once since when the coil would warm up it would mess with the resistance and cause it to run rough. Also, as David said, once it gets warm and expands any small fissure in the housing can cause an arch.

My second thought, also since i didnt see it on the list was the coolant temp snesor. If the sensor is constantly telling the ecu that the coolant is too cold and placing the engine in "warm up mode" even when the engine is at operating temp, it will cause it to run pig rich when it is unnecessary, like driving an older car with the choke open constantly.
 

·
Registered
Joined
·
1 Posts
Did this ever get resolved ~ The very 1st thing I would have tried would have been to run it with the O2Snsrs Disconnected to see if that had any effect & if not I then would have changed the CoolentTempSensor ~
ORR ~ DeanB
 

·
Registered
Joined
·
40 Posts
Hi All,

First off, I have been reading & researching this issue for months on end spending countless hours and late nights reading and have still been unable to solve my problem.

I have a 98 Legacy Outback EJ25, Manual Trans, 138,000 Miles. I bought it from the original owner about 2 years ago and it was running great until last year.

It starts just fine and idles smoothly when cold. It also drives good, great in fact when the engine is still cold - it accelerates smoothly and with plenty of power, but the second the temp gauge starts to move it begins idling rough, missing and loping and now it will even stall out and become very difficult to restart.

The fact that it ONLY happens after the engine has warmed up indicates to me that it is likely sensor/ecu related and not something mechanical. If it were mechanical (Timing belt off a tooth, injectors, valves, etc) then the problem would occur regardless of engine temperature, right?
I have a 98 Outback with this identical problem! Funny I don't remember this thread from before; just saw it this AM when searching.

Only difference on mine is that I DID get a CEL, and it showed "Cam position Sensor" malfunction. Also had a misfire code on cyls #2, #3, & #4. I checked the wires, and cleaned the cam sensor's contacts, and still got the cam sensor code, but the misfire codes were gone, so I replaced that sensor.......no difference.

I really don't think fuel pump; am leaning more toward ignition coil or coolant temp sensor. Are there 2 coolant temp sensors, or does the one that goes to the gauge also "talk" to the computer?
 

·
Registered
Joined
·
1 Posts
Has the fuel filter ever been changed? If it's clogged, it will lean out the mixture as you increase throttle. Unless you have documentation that it was changed per service schedule, I would do this to eliminate it as a factor. Otherwise, I have a Scangauge II on my 96 Legacy wagon, and it takes 5-10 minutes (summer vs winter) for the ECU to take over engine control. So if the problem persists, it's either a sensor or the ECU unit itself.
 

·
Registered
Joined
·
40 Posts
Still having this problem and it's driving me NUTS! Timing belt is good, as is tensioner. Replacing the coolant temp sensor today. Next I guess is the ECU :-(

Never did hear if Tree_D (started this thread) got his fixed? This seems to be a rather common problem; well, I've seen at least 4 separate posts from others suffering the same problem.

REPLACED:
Plugs
Wires
Coil pack
Cam Sensor
Fuel Filter

ALSO:
Checked wires
Checked timing belt & tensioners

Still throws a "Cam Position Sensor" 0340 code after warm-up, and "sometimes" throws cyl 3 & 4 misfire, and sometimes cyl #2 #3 #4 misfire. Why NEVER #1?
 

·
Registered
Joined
·
1 Posts
Still having this problem and it's driving me NUTS! Timing belt is good, as is tensioner. Replacing the coolant temp sensor today. Next I guess is the ECU :-(

Never did hear if Tree_D (started this thread) got his fixed? This seems to be a rather common problem; well, I've seen at least 4 separate posts from others suffering the same problem.

REPLACED:
Plugs
Wires
Coil pack
Cam Sensor
Fuel Filter

ALSO:
Checked wires
Checked timing belt & tensioners

Still throws a "Cam Position Sensor" 0340 code after warm-up, and "sometimes" throws cyl 3 & 4 misfire, and sometimes cyl #2 #3 #4 misfire. Why NEVER #1?
Kleenex,
Did you ever figure this out? I have a 2005 OBW xt and I'm experiencing the exact symptoms. I could use some help. I've replaced everything you have. Already out $1200. Any help would be fantastic.

Thank you!
 
1 - 17 of 17 Posts
Top