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question about unburned fuel


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Leaking leakdown tester? :) Good luck, hope you solve this mystery!
BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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Check the sealing surfaces where the o-rings seal. There may be damage in the metal, pits, deep scratches etc allowing fuel to bypass the o-ring sealing area. This must be the case if it happens with different injectors installed in the cylinder 2 position. You say you get so much fuel in the cylinder that it drips out past the exhaust valve. To eliminate the ECU sending any erroneous signals to injectors try disconnecting electrical plug from all injectors. Then cycle ignition key to on position(to turn on fuel pump) several times with few minute delay in between. If you rotate the engine to get the exhaust valves to open again and fuel comes out, then it's not the injector thats the problem (assuming this happens with 2 different injectors) but something at the sealing surface of o-ring.
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Leaking leakdown tester? :) Good luck, hope you solve this mystery!

 

Nice pun lol. Very annoying. And that thing is brand new..

 

Check the sealing surfaces where the o-rings seal. There may be damage in the metal, pits, deep scratches etc allowing fuel to bypass the o-ring sealing area. This must be the case if it happens with different injectors installed in the cylinder 2 position. You say you get so much fuel in the cylinder that it drips out past the exhaust valve. To eliminate the ECU sending any erroneous signals to injectors try disconnecting electrical plug from all injectors. Then cycle ignition key to on position(to turn on fuel pump) several times with few minute delay in between. If you rotate the engine to get the exhaust valves to open again and fuel comes out, then it's not the injector thats the problem (assuming this happens with 2 different injectors) but something at the sealing surface of o-ring.

 

thanks for your suggestion. When I pull the injector, I will have a real careful look again at the sealing surface (although I believe I did already and could only find that misalignment I show on that picture). But I'll check again and will report.

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Looking at that picture closer it looks like there is damage/scraping of the piece of metal that sticks out. I'm guessing that the tip of the injector hits that spot causing the injector to get slightly cocked(not straight)and causing a loss in the seal at the o-ring. You need to figure out what is causing the misalignment. The fuel rail doesn't seem to be sitting right.
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Quick update. I'll post pics and video later today hopefully..

 

First, I was able to pull the injectors on the driver side bank without making a mess. The spare injector I installed in cylinder 2 three weeks ago followed the same fate: small oring is pinched on one side. I'll post the video soon.

 

Second, I was able to realign the fuel rail by loosening the three bolts that holds it in place. Now you don't see any misalignment issue which is good (see pic below). Will this fix the issue of oring getting pinched? I don't know.

 

Third, I finally got around doing my leakdown test in cylinder 2. I made a video of it. I got a 2% leakdown. I was going to do the other 3 cylinders, but I was tired and it is a pain in the butt to hook that hose in these spark plug holes :mad:. I am happy about this result, although I was really surprised..

 

Now I wonder why I was getting a bit of roughness in that cylinder prior to swapping injectors and stuff. Roughness counts were at idle, and warm, and not always. So, questions:

 

1. I wonder if the injector in #2 was ever so slightly misaligned or something that the oring was not making a perfect seal, thereby leaking a tiny bit. And this was mostly noticeable at idle when warm? What do you think?

2. Would the unburned fuel cause the exhaust ports and valve stems to get darker? There's definitely more soot in this port than the other three.

3. I will probably send my injectors for cleaning/inspection. Thinking of witchhunters. Like 22$ per injector. What do you guys think?

4. Any other ideas/suggestions?

injector.png.25a474e12a7a81fe78b117c6608e3cb7.png

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Here is the (not so great) video I made for my leakdown test. Don't mind my accent and English. Tahitian boy speaking with a French accent..

 

[ame=http://www.youtube.com/watch?v=FVHzjc48UGs]https://www.youtube.com/watch?v=FVHzjc48UGs[/ame]

 

Here is the video of the injector from cylinder 2. Hopefully, you can view it in 1080p.

 

 

[ame=http://www.youtube.com/watch?v=CytT_sXdxlA]http://www.youtube.com/watch?v=CytT_sXdxlA[/ame]

 

Again, feedback is welcome.

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hi. first video says it is "marked as private".
BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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Great video! Congrats on that leakdown results for cyl #2.

 

So like you said, why the misfires? One thought is that if the misfire only happens when it's warm, perhaps a leakdown test on a warm engine might be different?

 

What else could it be? You've checked so much already. One thing I don't know if you checked is the injector seal that I suppose could cause a vac leak. See part #34 in your very useful full gasket kit contents post.

BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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Thanks. Actually the instructions for the leakdown tester do mention to do the test when the engine is warm. But no can do right now.. Maybe a valve issue would show up then ?

 

I did not think about part 34. That's true. I have these parts too from the 2013 valve clearance job. They never changed these parts.. I guess I could try to change these gaskets.

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How are both the front Air Fuel sensors acting? Is it really running rich? If a cat was clogged you'd have performance issues, like lack of power-exhaust cannot get out. So if you don't I'm thinking its just running rich and you have another issue that causes the Cat to get hot. And putting the DP will not fix that...even if it needs to be done.

 

 

This! If you were clogged cat in the up pipe you would definitely have some performance issues, turbo wont boost, no power on accel, etc. The glowing red catalyst would be an indication of an extremely large amount of fuel is in the cat. When they glow red they almost always sustain some type of damage, so if i was you, i wouldnt drive the car until you swap up's. dont wanna kill that turbo from the cat falling apart. did you happen to see what the catalyst temp sensor was reading? As travrach said, you may have an issue causing a rich a/f, or it could possibly be just that a ton of fuel had made it to the cat.

 

doh! didnt read all your post.

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no worries.

 

The car has been on jackstands since the day the cat glowed red. I like to play it safe :).

 

I am confirming that the red glowing cat was indeed from tons of raw fuel.

 

Planning to install a catless uppipe (anyone have one?), get the injectors checked out, and probably change the o2 sensor as well. Currently waiting on the guys at witchhunters to reply to my email...

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I can guarantee that cat glowed red from fuel exposure, since you had mentioned something about raw fuel coming out the WG at the arm. It is an accumulative process, it is all chemical reaction, so if the fuel dries but the fuel molecules are still there it will still cause the same effect.
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  • 2 weeks later...

Question....

 

I bought a set of orings from deatschwerks (really good deal btw--$14 for 8 orings compared to dealership..). I've never installed these orings before. How do you remove the pintle cap in order to install the small lower oring? Have any of you done this before?

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I believe you can leave the pintle cap on. Just use a pick/small screwdriver to carefully get under the o-ring, pry it over the ridge, and sort of work around the perimeter until it's off.

 

Installing the new one, just fit it on the end of the cap, then roll it over the ridge. Or you can try the removal method in reverse.

BtSsm - Android app/Bluetooth adapter. LV, logging, gauges and more. For 05-14 Legacy (GT, 2.5, 3.0, 3.6), 02-14 WRX, 04-14 STi, 04-14 FXT, 05-09 OBXT
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yeah. That's why I am afraid to stretch them if I force them to go over the pintle cap.

 

FWIW though, I was able to remove an old oring from an injector fairly easily just now. It does not look stretched either.

 

When I install the new ones, I'll probably use some lube too.

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Just as a short update, I have put new orings on the injectors (driver side), made sure the injectors clicked, and put them back in. They went in very easily, thanks to the fuel rails now properly aligned, and lubricated orings.

I recall, right before I got that unburned fuel issue, the injector would not want to get in there due to the pintle cap hitting the tgv assembly.

 

I'll report when I put the rest of the parts back on (re-install exhaust manifolds, uppipe, etc..)

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  • 2 weeks later...

Forgot to update...

 

Put everything back on last week with a catless uppipe now. No more 'unburned' fuel issue so far :). So basically, I have no clue how the fuel rails got misaligned with the tgv assembly in the first place. Strange..

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  • 1 year later...

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