1990 legacy misses when engine is warm poor mileage

[Deeron]

It's an EJ22 motor with 174k miles.  I bought this car a year ago and it has never run right since I got it. The engine runs smoothly when I first start it in the morning, then it misses at an idle when warm.  The check engine light was on, and I ran the codes and replaced the O2 sensor and purge control solenoid valve.  Now the CEL doesn't come on but it still runs poorly.  I also replaced the spark plugs and wires. I'm getting about 20 mpg.  I'm not sure if it's related, but I usually have to crank it over for a while to start it even when it's warm, and it appears to either not be getting gas or spark at first.  What do I check next?  Thank you!  

[Fairtax4me]

It common for the coolant temp sensor to fail and cause starting issues, and also cause poor fuel economy and rough idle. They're fairly inexpensive and can be considered PM if it doesn't fix it.

If you can use an ohmmeter you can test the sensor for proper resistance at a few different temperatures.

[Deeron]

Thanks Fairtax, I swapped the coolant temp sensor, but it didn't seem to change performance at all - in fact, my gas mileage went down afterwards, but that could be due to lots of city driving.  I'm not sure if it's just my imagination, but I think I can smell gas when the car isn't moving and the air conditioner is running.  Any other ideas?    

[AdventureSubaru]

Fuel filter is another preventative maintenance that can cause those symptoms. Can be a crapshoot when there's not a check engine light.

[Deeron]

Thanks Adventure Subaru!  I'll throw in a new fuel filter and see if that does the trick.  I'm hoping it's just something simple that I've overlooked. 

[heartless]

just out of curiosity, what kind of plugs and wires did you use?

 

Basic NGK plugs are the recommended type for this car.

 

cheap wires can also cause problems.  Had a set of cheap wires start arcing after getting to full operating temp on a road trip once - we were about halfway home at the time it started acting up. one of the plug boots had cracked and allowed the spark energy to arc to the block instead of going to the plug... a few wraps of electrical tape got us home and the wires got replaced asap with quality NGK wires.

[1 Lucky Texan]

fuel smell could be rusted-thru filler tube.

[Deeron]

Heartless: Yes I put in NGK spark plugs, but I don't remember the wire brand - I got them at NAPA.  I don't think that it's a plug and wire issue, since it runs smooth until the engine is warm, which make me think that it is a problem with some part the engine and/or emission controls.  I don't want to keep swapping out sensors and controls because the cost could really add up.  Could it be the ignition coil causing these problems somehow or at least the poor starting issue?  

 

Lucky: You've got that right!  The filler tube (and much of the car) is definitely rusted through.  When I fill up I can see a little gas spray out once the tank is full.

 

Any ideas on a sensor, vacuum line, or any part of the engine control system that could cause my symptoms?  I guess it could also be a combination of issues.          

[1 Lucky Texan]

vacuum gauge testing is cheap/free and might help rule-out one or two problems. Symptoms kinda seem like car might be running lean. You could also try spraying some carb cleaner around vacuum lines and intake manifold when it is missing at idle - listen for it to smooth out if it sucks in some cleaner.

 

fuel pressure maybe low?

[Deeron]

I've been off the grid for a while, but I want to revive this one so I can finally get my car running right.  Lucky Tex:  what would cause low fuel pressure?  A fautly fuel pump?  The carb cleaner test revealed no vacuum leaks.  

 

Also, the exhaust definitely smells like gas. 

 

Any ideas anyone?

[1 Lucky Texan]

scan for codes - misfire would put unburnt fuel thru the system.

[Fairtax4me]

If its misfiring you'll definitely smell gas.

A fuel pressure test may be a good idea, but if the pump were failing I think it would have died completely by now.

 

A compression check may be a good idea.

 

Also, because I've had this happen, check the timing belt. If one camshaft is out of time by one tooth you'll get misfires once the engine is warm.

[Deeron]

Lucky Texan - I scanned for codes when I first started troubleshooting the engine.  The 02 sensor and purge control solenoid valve were indicated, both of which have been replaced.  The fuel efficiency increased somewhat after swapping the 02 sensor, but it's still not great.  Is there a more in depth way of scanning for codes besides activating the blinking CEL light?

 

Fairtax - I was planning on changing the timing belt this fall so I guess that might solve the issue.  If the engine had compression that was so bad as to cause a misfire even when warm wouldn't the exhaust likely be smoking under most running conditions?  There's really no smoke in the exhaust that I've noticed.   

 

[1 Lucky Texan]

Fairtax suggested colant temp sensor - can cause good performance when cool/bad when warm with poor economy when warm - as he said - try it. Even if it doesn't help, you got new sensor and it's one less thing to suspect.

 

there are ways to get more data; elm327 BT adaptor with a smartphone with the Torque app, a laptop with a cable and the FreeSSM program or similar, some OBD scanners can get more data.

 

you might check this thread out; http://www.subaruoutback.org/forums/65-parts-accessories-performance/39426-freessm-complete-access-your-ecm-tcu.html

[Deeron]

Lucky T, I replaced the coolant temp sensor, fuel filter, air filter, 02 sensor, and purge control valve. I emptied the old fuel filter and found that it had some pretty nasty looking gas in there - rusty water must have gotten into the fuel system somehow.  I'm wondering if bad fuel may have messed up the injectors?  They all click when running, but perhaps the spray is poor?  Is there way to test this?  As for running those codes - that sounds like something that is way beyond my computer abilities.  The timing belt check will be next, but I would think that the poor running condition would be worse if it had skipped a tooth, and that it wouldn't idle well when cold.      

[1 Lucky Texan]

Techron is widely regarded as a decent fuel system additive. Other than that, replacement of the injectors is probably the most practical next step. I know there are ways to send them out for cleaning/testing. But, for the hassle and expense, why not just put new ones in?

 

consider puling the covers and inspecting the timing, it isn't all that hard and doesn't cost a nickel to look and confirm.

 

If the tank still has bad gas, consider another fuel filter change in the near future when decent gas has pushed the old stuff out. Or run the pump with jumpers or otherwise drain/pump the old stuff out. HEET or similar product might help with moisture in the fuel.

[mikaleda]

HEET or similar product might help with moisture in the fuel.

Just throwing this out there, you don't want to use heet in ethanol gas. Ethanol is alcohol and heet is alcohol your going to just compound the problem if you pour heet into ethanol gas. The only thing that I have found to work for water in ethanol gas is startron enzyme treatment, but anything that is made for ethanol gas I would feel safe in using.

[Deeron]

Lucky T, do you have any recommendations for a source of new injectors?  They are $150 a piece with the seal kits at the local parts store, so swapping all 4 would be pretty costly.  I agree that the hassle involved in sending them off probably isn't worth it, especially considering that it'll take my daily driver out of commission. 

 

You're definitely right: I need to just take a look at the timing belt.  That'll  be the next thing.  I don't have a garage so I have to choose my tinkering days wisely or else I'll end up turning wrenches in the rain and mud.

 

Also, good call on the second fuel filter change.   I added an entire bottle of Seafoam fuel additive so hopefully that helps clean out the tank.  Perhaps driving over all the local potholes will bounce the car around enough to suck all of the crap out of the fuel tank.  I'm thinking that there might also be a blockage in a fuel line that is causing these problems.  Would a fuel pressure test reveal that? 

 

Mikaleda, good to know!  I'll see if they carry startron locally.  How about Seafoam?  When I bought the fuel additive the parts guy told me that they'd been getting a lot of complaints about dirty gas lately, so I'd better find a good additive to use regularly.  There were about 15 options, so I just chose the one that that I recognized.   

 

Thanks for all the help, guys!

[mikaleda]

Seafoam is a good all around fuel system cleaner and would not hurt to run it and see if it helps. Its quite possible if its been wet and rainy lately that the gas station you got gas from could have had some water in their gas and only a few people are being affected by it. I would try getting gas froma different station next time you fill up and see what happens.

 

I would feel safe in using any fuel stabalizer that is made for ethanol I beleive sta-bil has a new product out that is designed for ethanol gas and it should also help with phase separation (water in ethanol gas) this can cause miss fires and other performance issues so it is a reasonable place to start if it was a sudden occurrence right after you filled up.

Another thing i was going to mention is your rusty fuel filler may be causing a vaccume leak causing issues, I beleive I've heard of this causing missfires at idle IIRC

[1 Lucky Texan]

does your engine have HLAs or solid lifters?

 

I have no experience buying injectors.

 

I think you can get a fuel pressure tester on loan from a parts store.

 

if you suspect a lot of debris in the tank, perhaps looking at the pump's 'sock' would be a cheap next step?

[Deeron]

Lucky T, how would I tell what sort of lifters it had?  Could I tell by looking under the valve covers?  As far as the pressure tester goes, the local parts store doesn't loan any tools.  I live on an island in Alaska, so there's not really an alternative choice.  Also, there's only two options for buying gas here, I have no idea which one may have provided the bad fuel.  Things are pretty limited here.  I might head out to the junkyard, though and see if I can find some injectors.  Do you know if all EJ22 injectors are compatible?  Are they compatible between the EJ22 and EJ25?  

 

I got around to checking to the timing belt this weekend and it appeared nearly new.  I didn't look at the entire thing, however, just the sections under the side inspection plates, but it looked pretty darned new.  I also took a closer look at the filler neck, which is pretty rusty but with no obvious holes.  I did, however notice that there is a bent metal tube coming down from the top of the filler neck.  This tube is very rusty and not connected to anything, and I was wondering if there should be a hose connected to this tube?  Where does the EVAP canister connect to the gas tank?  Could it be at this tube?  Mikaleda mentioned that a rusty filler neck could cause vacuum leaks and misfires, so perhaps this is my issue?

 

Thanks for all the help, folks!  

[1 Lucky Texan]

if the fuel system is open to the atmosphere - you can get a lot of water from condensation -MUCH  worse if the car spends a lot of time at less than a full tank. (more moisture-laden air PLUS greater water:fuel ratio)

 

I have no real experience with a soob that old. maybe someone else can chime in. But, if there is water in the fuel and/or rust on the pump's intake - that all needs to be addressed.