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NEED HELP ASAP (Cylinder 2 misfire driving me insane.)


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I'm going to try to pull a lv the ones I pulled already is blank because I reset the ecm. I have noticed that when engine is cold it misfires way more than when it's warm. Is this normal if the valves need adjusted?

 

 

 

 

Ah you know, the theory says the following: let's suppose an exhaust valve has little to no clearance. When the engine is cold, it should not exhibit too many misfires. And then, as the engine warms up the misfires counts or likelihood should increase. That is because the valve stem expands with heat, thereby decreasing clearance even more. This results in a valve which cannot fully close. You then decrease compression and increases misfire likelihood.

 

 

Having said that, my 06 had more misfires during cold idle and almost gone at warm idle. I swore it was rings (cause I checked everything else at that time except valve clearance). Long story short, it was actually due to a tight exhaust valve. So go figure :spin:

It's now been 25k after I readjusted the clearances and she's running great.

 

 

 

If that is indeed the issue and you catch it 'early', then you may be safe from a burnt valve.

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My 06 had 120k when she had this issue. Our 05 also had that issue. She had 73k.

 

 

side note: noticing your TGV voltages are slightly different. I never really paid close attention to these parameters. So not sure if that is OK. Other may chime in on that one.

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When you pull an LV, you want the 'Learn %' values to be close to 0%. That means the ECU does not have to correct too much the fuel delivery. This implies (in general) that you do not have any vacuum leaks.

As for the timing correction, you also want zeros everywhere. That means the ECU does not need to pull timing because it is not hearing knock. So that is a good thing to have zeros everywhere as well.

 

 

You have not driven enough to really populate the four Learn % fields. Although they usually update pretty quickly. In any case, so far everything looks good there.

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~13.5 psi should be the max target boost. Keep in mind intake temps may affect actual max boost level. In colder temp, it is easier to overboost a bit.

 

 

I don't know how 'far' you need to drive. It all depends. You just want to make sure that when you drive, you include all driving conditions (idling, accelerating, cruising, a bit of wot).

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It is a bit low I'd say. It also depends how long you were under load during your wot session.

 

 

Personally, I think it is time to check the valve clearances for real. You can do it with the engine in place.

 

 

 

Can't remember. did you do a compression/leakdown test?

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I did a compression test on all the cyli fees and if I remember right they were all 65psi +- 2psi. Also scoped every cylinder through the spark plug hole and all the cylinder walls looked fine and all pistons looked good. #2 piston had a little more carbon around where the spark plug sits but no damage. Guessing the extra carbon or just blackining is due to the misfires. This misfire just showed up about 4 months ago and I don't drive but maybe a hundred miles a week tops.
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Oh and if say #2 exhaust valve is to tight cause it wouldn't be to loose and cause a misfire plus the valves would be louder. How much damage could I realistically do if I had to wait a month or so to replace it? I know it could burn a valve but is that a real possibility with as little as I drive and just babying the car? Also is there an easy way to check if I have a burnt valve already?
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I actually drove for a while with my misfire issues. Maybe 5K? Not smart but that's what I did anyway. But YMMV.

 

The only way I can think of to check for a burnt valve is using a high quality borescope that could somehow 'look behind' once it has entered the combustion chamber.

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