Cyl 3 Misfire and limp mode after heavy load

[jtaskew]

Ok, picked her up last night. Stayed out of boost on the way home +/- 2 miles.
Flashed stock ECU/TCU put original plugs and coils back in.
Tech showed me a pic of cyl 3 plug less than a week old (40 miles) and the electrode was turning white. Especially where the electrode meets the threads. The others were lesser. He also told me the rear O2 was cooked, as in white.
He suspects it is running hot because of the tune. Maybe.
Compression was ok and rings also but the piston head has scoring. Also mentioned maybe the turbo could be having a problem. He said on test it runs perfect out of boost but when he got on it it started pinging and running bad. And when I say ping I really mean it sounded like someone threw thin pieces of metal in a blender at low. Any guidance is appreciated.

I am pretty much gonna have to sell it but I think my son wants it so I am going to try to keep it in family. I traded an old Tacoma in for a ridgeline (yes, technically it is not a truck) so I don't need another payment ATM. My son mentioned selling his sonic and getting the GTI. He drives like a granny. He knows how much I love the thing.

 

[Diggs24]

So the tip can't be found? Because it sounds like it might be in there bouncing around. Tunes don't just all of a sudden be bad. If the injector got nailed by the tip it might be unable to inject fully which is why the plug is white. I suggest start by pulling the injectors and looking at them.

 

[Diggs24]

Also pop the DP off and shove it out of the way and see if a fin is missing a chunk off the turbine.

 

[jtaskew]

So the tip can't be found? Because it sounds like it might be in there bouncing around. Tunes don't just all of a sudden be bad. If the injector got nailed by the tip it might be unable to inject fully which is why the plug is white. I suggest start by pulling the injectors and looking at them.

While the injectors are being checked the valves should be easy to check also right? To see if there was damage? Could have the tip made its way into the turbo? Someone mentioned loosening DP and checking turbo. Good advice.

 

[jtaskew]

When the first BIG misfire happened. I can only assume that is when the electrode dipped out I want to say I heard a pinging make its way "under" the car. Could this have been the tip blowing past turbo, possibly taking some with it to the cat? Also, can we assume this might have been a progressive problem over months? Which could mean I have had an issue for a bit? I want to say the plugs had less than 10k miles.

 

[Diggs24]

You need a boroscope with a little angled mirror on it to see the valves. Doubt you'll have any better visibility through the DI ports.

 

[Diggs24]

When the first BIG misfire happened. I can only assume that is when the electrode dipped out I want to say I heard a pinging make its way "under" the car. Could this have been the tip blowing past turbo, possibly taking some with it to the cat? Also, can we assume this might have been a progressive problem over months? Which could mean I have had an issue for a bit? I want to say the plugs had less than 10k miles.

The tip would probably not make it past the cat, the holes in the matrix in those are pretty small. But yeah it could sound like that bouncing around making its way back there. yeah, pop off the DP and look.

 

[Subliminal]

Are you widening the gaps before installing? If so, are you prying on the electrode/tip?

 

[jtaskew]

You need a boroscope with a little angled mirror on it to see the valves. Doubt you'll have any better visibility through the DI ports.

The car idles pretty smooth. I did notice when I got it home oil was about 160 deg, so not fully warmed, with non oem plugs, coils and tune still on it would stumble a little every 3-4 rotations. But it drove pretty good out of boost under 3k rpm in D mode. Will check both sides of turbo this weekend and a buddy mentioned checking injectors but I don't know how to seal them to get them back in. I watch humble mechanic but a tool was needed to reinstall them. My friend also said the electrode, since it has not been found, might have kissed the turbo on the way out.

 

[jtaskew]

The tip would probably not make it past the cat, the holes in the matrix in those are pretty small. But yeah it could sound like that bouncing around making its way back there. yeah, pop off the DP and look.

Honestly yes, it did sound like it made it to the cells. I just did not know if that could be heard from in cabin.

 

[scrllock]

imo turbo is probably hosed, could have been hit by the tip and/or it's still hanging out in the turbine/DP area.

definitely check your injector, get the seal kit since you need to re-do the seal anyway if you're removing them.

 

[jtaskew]

Are you widening the gaps before installing? If so, are you prying on the electrode/tip?

The gap looked ok on the most recent set. I did not check the RS7 plugs. One of which dropped the electrode.

 

[jtaskew]

imo turbo is probably hosed, could have been hit by the tip and/or it's still hanging out in the turbine/DP area.

definitely check your injector, get the seal kit since you need to re-do the seal anyway if you're removing them.

What is the best way to relieve rail pressure?

 

[scrllock]

What is the best way to relieve rail pressure?

pull the LPFP fuse and the DI electrical connection. then let the car start and die out.

 

[Daks]

What is the best way to relieve rail pressure?

Ain't that bad if you don't relieve it. Just have a cloth ready to soak some up. But then again, I have been more liberal with my hpfp and lpfp installs than some.