05 LGT Misfire that wont go

[Turbine_junkie]

Hello fellow LGT owners,

 

I have a 05 5AT LGT Wagon, 142k miles. No mods other than bigger Anti Roll bars. Ever since I got the car 3.5 years ago, it intermittently threw P0302 cylinder misfire on #2. It would go away within a few days and not come back for months just to repeat. I do smell gas on start up which goes away, so I thought it was the injector.

 

This year, it has been happening more frequently. I have done following,

 

1. New plugs. NGK iridium. Gapped at 0.028"

2. Swapped injector with # 1 cylinder

3. Swapped coil with # 4 cylinder

4. Cleaned MAF sensor

5. Checked vacuum leaks

6. Compression test (cold)

#1 125 psi

#2 115 psi

#3 125 psi

#4 122 psi

 

7. Timing Belt Check: It was off one tooth.

Replaced timing belt water pump and all idlers.

 

8. Top end cleaning after timing belt change to clean any carbon.

 

So far, all steps, the code comes back as P0302.

 

Compression #'s are not great but its an old car and I did the test cold. No obvious culprits other than slightly low on #2.

 

I am thinking this is either ringland or valve clearance. Ringland can be ruled out as I DONOT have an oil consumption issue.

 

Any opinions will be appreciated !

[relative4]

Was the compression test before or after discovering the timing was out?

[Turbine_junkie]

Was the compression test before or after discovering the timing was out?

 

It was done before fixing the timing belt situation ! recommended to do again after ?

[relative4]

Yes. Do you still have the misfire after fixing the timing?

Just noticed you didn't mention replacing the timing tensioner. You did that, right?

[Turbine_junkie]

Yes. Do you still have the misfire after fixing the timing?

Just noticed you didn't mention replacing the timing tensioner. You did that, right?

 

Yes. Tensioner was replaced. Car misfires but slightly less than before. I thought the carbon build up due to all misfires is causing some issues with valve seating. So I used BG44K to clean using vaccum line, but I think that made it worse.

 

If it matters, the timing belt kit was Aisin. All parts Japanese.

 

I will check compression again I guess. Curious question though, compression is checked over a few revolutions of the crank, so how would timing affect it. Just trying to understand !

[baconbits]

If a valve is partially open, it won't build up compression properly. I imagine it would have to be off many teeth (6+) but then you're getting to the realm of valves kissing pistons and that would be on all cylinders, not just one.

[Turbine_junkie]

Just an update. Any opinions still welcome.

 

I was all set to do a valve check. Got the feeler gauges and all. After reading https://legacygt.com/forums/showthread.php/just-another-misfire-rough-idle-thread-235633.html thread though, I am not encouraged to do it. My misfire is looking more and more like his story.

 

It is more prominent at idle but I can make it misfire if I stomp on throttle and the transmission doesn't shift into a lower gear or when there is a steep grade and just before the tranny shifts. If I shift down though, the misfire is gone. Fueling issue ?

 

On a different note, do I worry about the pre cat damage misfires cause and an exploding turbo due to this ?

 

Also ordered a FreeSSM cable to see if I can log any of this. I know FreeSSM cant but there is another tool that I found. Will post a link if it works.

[StkmltS]

Where in the world (literally) do you live?

 

Your misfires won't cause the pre-turbo cat to explode any sooner than it would otherwise. If it helps you feel better you can buy a non-catted up pipe from an '07+ LGT.

 

After you figure out how to log data, spreadsheets and graphs (and people on here) might help point you in the direction of where your problem is coming from. At this point it's really hard (even for you) to know what the motor is doing.

 

If you bought one of the cables listed here (https://www.btssm.com/?page=hardware) then BtSsm is definitely what you'll want to use to log. Even if you have to buy an old android device it's way easier than lugging around a laptop.

 

OpenECU and RomRaider (both free) are the software programs you'll need to use your laptop with your car. It's a bit of a headache getting the software installed correctly at first, but after that it's fairly easy to use. Understanding what changes to make is black magic and must be approached with extreme caution. Monitoring and logging is completely safe though.

[Turbine_junkie]

Where in the world (literally) do you live?

 

Your misfires won't cause the pre-turbo cat to explode any sooner than it would otherwise. If it helps you feel better you can buy a non-catted up pipe from an '07+ LGT.

 

After you figure out how to log data, spreadsheets and graphs (and people on here) might help point you in the direction of where your problem is coming from. At this point it's really hard (even for you) to know what the motor is doing.

 

If you bought one of the cables listed here (https://www.btssm.com/?page=hardware) then BtSsm is definitely what you'll want to use to log. Even if you have to buy an old android device it's way easier than lugging around a laptop.

 

OpenECU and RomRaider (both free) are the software programs you'll need to use your laptop with your car. It's a bit of a headache getting the software installed correctly at first, but after that it's fairly easy to use. Understanding what changes to make is black magic and must be approached with extreme caution. Monitoring and logging is completely safe though.

 

I am by Akron, OH.

 

Good to know on misfires & accelerated CAT damage. I was thinking that raw fuel in Pre CAT wasnt good which is made worse by possible Pre CAT into Turbo.

 

All this because I am assessing risk on how quickly do I need to fix this. Wife is not working currently so the car sits most of the time. I was hence not in rush and was going to pursue the diagnosis myself. Thats when I thought of Pre CAT

 

Agree on ECU changes being a black magic. At this time, I plan on monitoring and logging only. Laptops are it for me. I am an android person but just am more comfy with laptops for any data acquisition, may be from work where I sometimes instrument vehicles for handling studies.

 

I bought cable from here.http://blog.obdii365.com/2016/06/09/review-on-subaru-freessm-v125/

 

ECUexplorer is what I downloaded that claims to do the logging.

[m sprank]

Basics.

 

 

Plug gap, correct plugs, no damage?

 

What is your compression? Leak down?

What is your fuel pressure?

 

 

If not plugs/coil pack, idle misfires tend to be 100psi or less compression (in affected cylinder) or a failing FPR for cars in your year/mileage range.

[Max Capacity]

OP, I hope you listen to m sprank. He's one of the go to people for help with these cars.

[Turbine_junkie]

Basics.

 

 

Plug gap, correct plugs, no damage?

 

What is your compression? Leak down?

What is your fuel pressure?

 

 

If not plugs/coil pack, idle misfires tend to be 100psi or less compression (in affected cylinder) or a failing FPR for cars in your year/mileage range.

 

Thanks for the tips ya'll.

 

Followed the basics. See steps in my first post.

 

No damage on the plugs. In fact, the plug on # 2 was a bit cleaner than other cylinders but all 4 plugs were normal.

 

Compression numbers are in first post. A bit low (not 100 psi low) in problem cylinder, but relative to other cylinders, not that far off. Cold #'s as well. I expect more when run hot.

 

I have not checked fuel pressure. Will do. just to understand, fuel pressure must affect all 4 cylinders, no ?

[m sprank]

No. Fuel pump duty at start up is 100%. Fuel pump duty can hang at 100% even when coming to a stop depending on driving style. As the fpr begins to fail the 100% duty cycle of the pump can overpower the regulator at idle causing a hi pressure condition. This condition can be alleviated by an injector opening. So 1 cylinder misfires and the others are able to cleanly fire as the misfire cylinder dropped the overall fuel pressure.

[m sprank]

Ring land failure can not be ruled out just because you are not consuming oil. I have disassembled ej255s to find broken ringlands in cylinders with 140+ compression.

 

Your compression is low enough to be a concern. Timing off one tooth was an issue. You need to check leak down too due to the previous timing issue.

 

One thing at a time, but you could be looking for a bandaid to place on a broken femur. Hi mileage, worn engine that was running out of timing (Interferance engine).

 

Compression, timing, spark, air, fuel.

[Turbine_junkie]

No. Fuel pump duty at start up is 100%. Fuel pump duty can hang at 100% even when coming to a stop depending on driving style. As the fpr begins to fail the 100% duty cycle of the pump can overpower the regulator at idle causing a hi pressure condition. This condition can be alleviated by an injector opening. So 1 cylinder misfires and the others are able to cleanly fire as the misfire cylinder dropped the overall fuel pressure.

 

Thanks for the explanation. I will find some time and diagnose these suggestions.

[Turbine_junkie]

Ring land failure can not be ruled out just because you are not consuming oil. I have disassembled ej255s to find broken ringlands in cylinders with 140+ compression.

 

Your compression is low enough to be a concern. Timing off one tooth was an issue. You need to check leak down too due to the previous timing issue.

 

One thing at a time, but you could be looking for a bandaid to place on a broken femur. Hi mileage, worn engine that was running out of timing (Interferance engine).

 

Compression, timing, spark, air, fuel.

 

Thanks again !!

 

I am not worried about any damage due to the wrong timing. The tensioner was leaky when I replaced it; which makes me think over 40k miles, the timing belt relaxed slowly due to that failing tensioner. Subaru FSM states that it has to be 3 teeth off for interference to occur.

 

Good to know on Ring lands. That might as well be a problem. I guess I will try the cheaper fixes first.

 

Agree on a the old engine quote. Right now, this car doesnt see a lot of use so I dont want to jump on ring-lands or leaky valves conclusion without trying to eliminate some of the other cheaper/ easier to do stuff.

[gimpydingo]

Ring land failure can not be ruled out just because you are not consuming oil. I have disassembled ej255s to find broken ringlands in cylinders with 140+ compression.

 

Your compression is low enough to be a concern. Timing off one tooth was an issue. You need to check leak down too due to the previous timing issue.

 

One thing at a time, but you could be looking for a bandaid to place on a broken femur. Hi mileage, worn engine that was running out of timing (Interferance engine).

 

Compression, timing, spark, air, fuel.

 

Not trying to jack, but with his compression test done on a cold engine is that really a concern? Numbers seem reaonable for cold test. Only reason I ask is because my number are similar on a cold test. Car pulls strong, but does use some oil when getting on it.

[m sprank]

Rarely and I mean RARELY is a compression test accomplished hot on a turbo subie. Plug placement greatly hinders the ability to perform the task. A fresh ej255 is usually in the 145-150psi range cold.

 

Getting close to 100psi is misfire time.

 

If the tgv seized closed you would misfire on that bank at 3300rpm and above. This is when the tgv would open.

[Turbine_junkie]

No. Fuel pump duty at start up is 100%. Fuel pump duty can hang at 100% even when coming to a stop depending on driving style. As the fpr begins to fail the 100% duty cycle of the pump can overpower the regulator at idle causing a hi pressure condition. This condition can be alleviated by an injector opening. So 1 cylinder misfires and the others are able to cleanly fire as the misfire cylinder dropped the overall fuel pressure.

 

https://photos.app.goo.gl/R7TwghVLdVcBeULWA

 

In the picture above, trying to find which one is fuel delivery hose to measure fuel pressure. FSM states one should use fuel delivery line with and without vacuum connected.

[m sprank]

The line the regulator is on is return to the tank. Measure after the regulator. Looking for 43psi with no reference to vacuum. -1psi of fuel for each psi of vacuum, +1psi of fuel for each psi of boost.

 

 

 

If fuel pressure is good, might as well swap an injector to see if the misfire moves with the injector. Gives you a chance to check the electrical connectors too.

[Turbine_junkie]

Just an update. Any opinions still welcome.

 

I was all set to do a valve check. Got the feeler gauges and all. After reading https://legacygt.com/forums/showthread.php/just-another-misfire-rough-idle-thread-235633.html thread though, I am not encouraged to do it. My misfire is looking more and more like his story.

 

It is more prominent at idle but I can make it misfire if I stomp on throttle and the transmission doesn't shift into a lower gear or when there is a steep grade and just before the tranny shifts. If I shift down though, the misfire is gone. Fueling issue ?

 

On a different note, do I worry about the pre cat damage misfires cause and an exploding turbo due to this ?

 

Also ordered a FreeSSM cable to see if I can log any of this. I know FreeSSM cant but there is another tool that I found. Will post a link if it works.

 

UPDATE to this if that matters trying to figure it out,

 

The car most certainly misfires only under 2000 RPM when,

• Starting from a stop
  
• coming to a stop
  
• on a grade, if tranny doesnt shift on time (happens some time)
  
• Almost always these misfires are a gross misfire. Blinking CEL
  
• SPORTS mode seems to help with all but the very low speed as it keeps the engine above 2000 rpm
  
• I used to have a gas smell issue at start up but after timing was fixed it is not a issue
  

 

EVERY SINGLE TIME we fill the car up ( NOT overfill, until the pump shuts off), the car hesitates and stalls on first start. The second start is normal until we fill up next time. Is this related any ways ?

[relative4]

Sher sounds like the evap purge valve.

[08SpecB_DE]

Sher sounds like the evap purge valve.

 

What he said. OEM is the way to go for evap parts. Might not be a bad idea to grab one from a local auto parts store and make sure it fixes your problem. Order oem and use aftermarket until the factory part shows up then return the aftermarket valve.

[Turbine_junkie]

Sher sounds like the evap purge valve.

 

What he said. OEM is the way to go for evap parts. Might not be a bad idea to grab one from a local auto parts store and make sure it fixes your problem. Order oem and use aftermarket until the factory part shows up then return the aftermarket valve.

 

Ya'll talking about the stalling after fill ups I think. Will look into this as well. Thanks. Any chance this causes misfires, wouldn't think so.

[08SpecB_DE]

Yes we are. Ive seen them cause lean conditions and rough idles when they're stuck open. I can't recall them throwing a misfire on one cylinder in particular.