Just another misfire/rough idle thread...

[TheMonaLisa]

I've thought "the only thing left is..." about 15 times. That's why now I only say "the next thing is..."

 

Sent from inner space.

 

 

 

Just discovered what a noid light is. Going to pick one up and give that a try.

[strikerusn]

I'm having kinda the same issue. Its just misfiring in cylinder 2, changed spark plugs, coils packs, did compression test and it came out well.. I just recently upgraded the turbo to the vf52 and fuel pump. Im still waiting for the tune. And it actually started doing it after I upgraded the turbo. How did you realize it was the piston? Was it when you took it completely

apart?

 

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[xt2005bonbon]

^ did you swap injectors as well? When does it misfire? cold or warm idle? any rpm? how many miles on this engine?

[StkmltS]

I'm having kinda the same issue. Its just misfiring in cylinder 2, changed spark plugs, coils packs, did compression test and it came out well.. I just recently upgraded the turbo to the vf52 and fuel pump. Im still waiting for the tune. And it actually started doing it after I upgraded the turbo. How did you realize it was the piston? Was it when you took it completely

apart?

 

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My problem isn't piston-related... I still haven't figured out what's causing my misses.

THANKS FOR THE REMINDER!!!!!!!!!!!!!

:spin: :spin: :spin: :spin: :spin: :spin:

 

I'm not mad at you, but you get the idea.

[strikerusn]

My problem isn't piston-related... I still haven't figured out what's causing my misses.

THANKS FOR THE REMINDER!!!!!!!!!!!!!

:spin: :spin: :spin: :spin: :spin: :spin:

 

I'm not mad at you, but you get the idea.

Haha yeah. I see. Does your car need a tune? That's what I'm thinking that it could be. It started doing it after I upgraded the turbo and water pump.. But who knows car is currently on stand by till next week. Hopefully it gets fixed asap. I really miss driving it -_-

 

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[strikerusn]

Updated got the car back. Car is no longer misfiring at cylinder two. So that's definitely a good sign. But now at cylinder 4. So.... After moving the spark plugs around and coil.. I found out it can be either one. Thing is don't know which one it could be cause I didnt keep track of what was moved.. Aint that smart.

 

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[xt2005bonbon]

Yeah. You should have swapped just one part at a time, and observe. But that's great news. This is an easy fix.

[strikerusn]

Yeah. You should have swapped just one part at a time, and observe. But that's great news. This is an easy fix.

Yes definitely great news. Called the stealership, coils are 110 and takes 2 business days. Havent ordered them yet. Car will being going to road race engineering soon to get a tuned and ill have them figure out what's going on. Wish me luck. Hopefully its not more then just an arm and a leg

 

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[xt2005bonbon]

check out heuberger subaru dealer from Colorado. Last time I got one from them, it was 76 bucks (+shipping). You may be able to save 20$ or something. But then again, you need to confirm it is the coil first.

[StkmltS]

Yeah, just move them around and see if the miss moves too. But first, as you already discovered, mark the coil packs. I'd mark them A-D just to not get confused with the cylinder numbers, and then write down in a note pad which packs you swapped.

 

Example:

Starting locations (permanently marked): "A"=cyl1, "B"=cyl2, "C"=cyl3, "D"=cyl4

Change: coil D moved to cyl1, coil A moved to cyl4

[strikerusn]

Yeah, just move them around and see if the miss moves too. But first, as you already discovered, mark the coil packs. I'd mark them A-D just to not get confused with the cylinder numbers, and then write down in a note pad which packs you swapped.

 

Example:

Starting locations (permanently marked): "A"=cyl1, "B"=cyl2, "C"=cyl3, "D"=cyl4

Change: coil D moved to cyl1, coil A moved to cyl4

Yeah I'm planning to do it but my work schedule and school doesn't help me so ill rather have someone work on it. Only day ill be able to do it is Sunday morning and I usually just get high off my ass and study so I think ill rather have someone do it for me but I'm thinking its going to be the spark plugs.

 

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[Tschagfreebird151]

Hello fellow Legacy enthusiasts,

I was having a bunch of misfires for the past two or three months. I also had an oil leak on both sides of my valve covers. So I replaced the valve covers, and my CEL light continued to show. Next, I replaced my Diamond coil overs with new stock ones and replaced the spark plugs. Drove the car around and the next morning the CEL Lights appeared. So, I did a compression test results were 130's-140's, and my leak down test results were less than 10% on all four. However, from the leak down test I could see a large amount of smoke coming from a crack in the stock top mount inter-cooler. My Engine has 171K on it, so I replaced the inter-cooler with a new AVO one.

My Spec B seemed to be running better, but three days after the CEL lights came back. Hooked my cobb up and ran codes same misses as before Cylinder #2...

But, just last Sunday I took the B to sell some old Bilsteins to a person on craigslist for $90.00 in South Center. I let my dad drive the car back to Everett, and he got on the throttle and took the car up to high revs, 5K RPM's my (CEL light was showing this whole time by the way!!). I had my Cobb hooked up and was watching for misses, there was not any new ones reporting. I did not clear the code when I turned off the car, and did not clear the code when I got back to my house later that evening. The next morning, with ice on the windows, I started the car and was warming it up for like 30 to 60 seconds like I always do, and my CEL Light blinked three times then completely went away. I have been driving it everyday this week and still no more Cylinder #2 missfire.

I believe that by driving this car hard, I heated up the valves and blew out all that crap right on out of my Invidia Exhaust. I think these engines are designed for high revs, and and should be driven this way every now and again.

I love this car, and seeing the CEL Light really made me angry. So happy to not see it these last couple of days.

[xt2005bonbon]

The CEL may come back

 

did you do your leak down test warm or cold? Cause I had a super tight valve, did a cold leakdown and it was less than 10%. Intermittent CEL also.

SO, although YMMV, I think you should check your valve clearance.

[StkmltS]

Your CEL probably went away on it's own because the car saw enough time/miles without any misses.

 

Hopefully you did enough to keep it from coming back.

[Tschagfreebird151]

I did the leak down test cold. Should I have done it warm? Would it make a difference? I think that if you have leaks, they will show up regardless of engine temp...

 

Yes, I do think that I probably should adjust the valves, but I just fixed the leaks and I do not want to take it off and do that job again.

 

This morning before I drove to work, as I was warming the car for 30 seconds, the CEL flashed three times but then went away again. Tomorrow I am going to hook the cobb up again and monitor start up.

 

My hope is that my CEL does not come on again for another year or two, or when my engine hits 190K whatever comes first. Then I am going to pull my engine, and do my timing, water pump, adjust the valves, and just go through a lot of the bottom half of the motor, then put in new motor mounts and install studs.

 

I am going to keep driving the car like I have been doing so far, shift when I hit 4500, or 5000 RPMs, and continue to watch oil, change every 3k using full synthetic.

 

And as long as the CEL light stays away, I am going to take it to a tuner, and have the engine tuned for the new larger AVO I installed last week, that will be the second time this car has been on the DYNO, and it will be interesting to see those numbers.

 

Cheers friends, lets hope the Check Engine Light stays away.

[xt2005bonbon]

I did the leak down test cold. Should I have done it warm? Would it make a difference? I think that if you have leaks, they will show up regardless of engine temp...

.

 

Yes, a leak down test should be done warm, not cold. When the engine is at operating temp, the valve stems (especially on the exhaust side) will elongate a bit.

 

As I said, in my cases (two different cars), I had one super tight exhaust valve on cylinder #2. But both leakdown tests (cold) were showing great results. So I concluded that my valves were fine and that I had a cracked ringland or something. But one day, I felt like checking the valve clearance on the driver side. And BAM (as Freiburger says ), I had one super tight valve.

 

Since cylinder 2 is missing, you really only have to take out the battery, coil, spark plug and valve cover to check the clearance. Not that hard.

 

I am not saying that is the issue, but if it is and you keep driving it, you will most likely burn the valve. And then it will cost you much more to fix it.

[StkmltS]

It's warming up outside, birds are singing, trees are budding, and my car is missing.

Moral of the story: everything gets better except my car.

 

To readers with wideband O2 sensors...

Can you guys do me a favor and record a short log at idle (few seconds) that shows the difference in readings between your stock front O2 sensor and your WBO2?

 

My stock sensor and wbo2 don't read the same, and I'm wondering if my stock sensor could be causing my problems.

[StkmltS]

Bump for comments on the observed dissonance between my O2 and WBO2 sensors.

[heiche]

That's a tough one, since there are 2 sensors reporting different values. The difference is substantial too. Which one is correct? Can't really tell. Not that I like to throw money at an issue, but perhaps a new front AFR sensor (oem) might be a good idea if it's got a lot of miles on it anyway. Then you could test again and compare.

 

Another thought is to get a 3rd reference and log the rear O2 sensor, even though it's narrowband and you can't compare apples-to-apples. However, it will be a sanity check for when the AFR mixture crosses above or below 14.7 (narrowband is to a light switch as wideband is to a light dimmer)

[rhino6303]

http://cloud.tapatalk.com/s/58dbc4e259db0/BtSsm_20170329_071158_logs.zip

Here is a quick log of mine.

[StkmltS]

Thanks for the input. I hadn't though of logging the rear o2 sensor.

 

My problem:

I've had a misfire for a long time, mostly, but not limited to cylinder 2

 

What isn't the problem:

A ton of things (see post #1)

 

What has worked (slightly):

Tuning to add more fuel

 

Thinking out loud here...

If my O2 sensor is reading lower than reality, that would mean that my target AFR would be leaner than it should be, which can/does cause misfires/knock. Measurements from my new WBO2 don't match the measurements from my 12 year old stock O2 sensor, and changing the tune to target a richer AFR has improved (reduced) the misfiring; both of these things support the idea that my front O2 sensor may be bad. It would also explain why I mostly see misses at idle, because that's when the ECU has the lowest target AFR. Man, typing this stuff 'out loud' really helps me think things through better.

 

My PLX wbo2 controller has an analog output that supposedly can emulate the signal from a narrowband o2 sensor, so before I spend (more) cash on a potential fix I'm going to figure out how to hijack the OEM signal to see if that changes anything.

[StkmltS]

http://cloud.tapatalk.com/s/58dbc4e259db0/BtSsm_20170329_071158_logs.zip

Here is a quick log of mine.

 

Thanks!

[heiche]

So if you log the rear O2 sensor, when it crosses about 0.5V (either going up or down), that is considered crossing 14.7 AFR. Any lower Voltage means leaner, any higher Voltage means richer.

 

So you could probably make a few vertical lines on your graph where it crosses 0.5V, and see if either your oem AFR sensor, or your external WBO2 is near 14.7 - and that would be the "correct one".

 

edit: One slight gotcha though, is that the rear O2 is behind the cat, so it does sway the AFR a little, but not too much.

[Siq]

Hello everyone. Pretty new to LGT but have owned a couple subi's

 

Okay so I got rough idle, and Missfire in #2 & #4. Ive replaced all 4 coils, spark plugs and MAF. Idle is a little better but still have misfire in #2 & #4. Took out both injectors and took off negative to battery. cleaned both injectors with carb cleaner put them back in and started it up. No cel, went for a little cruise and cel flash a couple times then goes off. Hit the highway cel comes back on, but under wot it will go away sometimes. (I don't wot all the time so just seeing what it does)

 

When I get home I let the 05 lgt idle in my driveway, no cel only rough idle. I rev it around 3k rpm cel flashing. Let it idle and it goes away.

 

I then turn it off and let it sit over night. In the morning I start it up and solid cel comes on and stays on.

Today I am gonna switch injectors and see if it follows. I got a new timing belt kit coming in, in hopes that it gives a better idle. It got 190k so its basically time anyway.

 

The guy I bought it from said he never had issues until he got it tuned. He claimed after a couple pulls it threw misfire codes. So I sent my tuner his final log and he went through and tweaked it (a lot) he said it was pretty sloppy job. So hopefully with new tune and timing belt it will calm down

[LatentWagen]

Did you do a compression test when you did plugs/coils? Might be a tired motor, on it's way out... or maybe you have a good bottom end, and good compression, but tight exhaust valves. Both are common scenarios at higher mileage on these cars.

 

I wouldn't do a timing belt job on the car until you know what you're working with.