Just another misfire/rough idle thread...

I'm also removing the rods, dividers, motors, and sensors.

The head keeps staring at me saying "just pry me open a little bit... come on, you know you want to see what's inside." It's so hard not just going in for a little peek. Buying new gaskets (and studs?) would be enough to keep me from getting out of debt this month so it'll just have to wait.

Can't you use your camera thingy to recheck the valves? Should be easier from this angle, no?

I was thinking the same thing until I came to the brilliant realization that I can't see the exhaust valves from the intake side of the motor.

The best I'm hoping for is to find enough room on the back side of the valves for the camera to move around just enough to be able to look past the open valves and see part of the cylinder wall. I don't think the valve opens far enough to get the camera past it.

Couldn't you just put the camera in thru the spark plug hole? Can you bend it to look back?

I ordered a tune from Tuning Alliance with the Cobb APv3 - still on my engine break in oil but one a single commute to and from work with the new tune, keeping the car below 3500 rpm, she's definitely running better than she was on the stock tune.

Couldn't you just put the camera in thru the spark plug hole? Can you bend it to look back?

 

I ordered a tune from Tuning Alliance with the Cobb APv3 - still on my engine break in oil but one a single commute to and from work with the new tune, keeping the car below 3500 rpm, she's definitely running better than she was on the stock tune.

I stuck the camera in there and poked around a bit, but there isn't much room in there to move it around much. I did get a good view of the piston though. Navigating the camera consists of twisting and pushing it's [uSB] cord, so not nearly as maneuverable as the ones they use in spy movies. I could try pushing the camera through the spark plug hole backwards, but with the cord doubled-back like that it's a tight squeeze and I'm terrified that it would get wedged in there and I'd have to perform heart surgery to get it out.

Did they give you a break-in tune or are you just taking it easy on your stock tune?

I am taking it easy on the TA tune - just changed the break in oil yesterday and did a couple WOT pulls last night - car definitely moves

I need to do a few logs to send over to them. Overall drivability is better than stock, less of that low RPM surge (although it's still there). But for the 'first shot' it's amazing what they can do.

Well, my borescope fits pretty well down by the intake valves, here's what I found.

The intake valve is fully open, near the beginning of the intake stroke.

What's with all of the crud that looks like it's creeping up the side of the cylinder wall? All of the pistons look similar to cyl#2.

The piston looks much cleaner than it did when I last 'scope'd it (

Fixed it.

Youtube is blocked here at work so I had to remote into my home computer to get the links fixed. TeamViewer to the rescue once again.

I'm going to poke around a little harder and try to find a way to see the cylinder wall. I need to know if there's scoring or not.

Speaking of scoring: yesterday my wife agreed that next month we can start saving for a new motor. "And if there's enough left over, I'm gonna fly you all down here to help us dedicate it."

I'm going to poke around a little harder and try to find a way to see the cylinder wall. I need to know if there's scoring or not.

 

Speaking of scoring: yesterday my wife agreed that next month we can start saving for a new motor. "And if there's enough left over, I'm gonna fly you all down here to help us dedicate it."

Packing bags...

"And if there's enough left over, I'm gonna fly you all down here to help us dedicate it."

"I cant swim, Clark"

To be more precise, it only misfires under vacuum. It still occurs at high RPM when MPH=0, and I have a few logs where it sporadically showed up when MPH>0 (not a continuously rising count though).

The head keeps staring at me saying "just pry me open a little bit... come on, you know you want to see what's inside." It's so hard not just going in for a little peek. Buying new gaskets (and studs?) would be enough to keep me from getting out of debt this month so it'll just have to wait.

You wont have a vacuum condition at higher rpm even with a 0 veh. speed.

Compression test wont tell you how well the cylinder is sealing. I think ive stated this before. a leakdown test will show a burned valve. it just may not be severe enough to stick out at you. if you dont see any scoring with the boroscope then your cylinder walls should be ok. i had 108k when i pulled my motor due to #4 ringland failure, walls were not scored up.

in the pictures you have of the cylinder wall and piston the junk at the top of the cylinder wall is called ring ridge its just the area on the cylinder wall that does not get scraped by the piston. I would venture to say your ringlands in that cylinder are PROBABLY ok. When i pulled the head off my motor for the fuct ringland, the ring ridge was excessive, and comprised of nothing but burned oil sitting at the top, in a cake like consistency.

sorry i havent been around here lately man, started a new job.

You wont have a vacuum condition at higher rpm even with a 0 veh. speed.

When I'm sitting in my driveway with my foot on the throttle my boost/vacuum gauge definitely shows negative pressure (vacuum). There's a tiny little spurt of boost (positive pressure) when I first stomp on the pedal, but it immediately drops to somewhere around 10-15 in/hg if my memory serves me right. Even cruising on the highway the motor is under vacuum most of the time. I don't want to internet argue, I just don't understand what you mean.

Compression test wont tell you how well the cylinder is sealing. I think ive stated this before. a leakdown test will show a burned valve. it just may not be severe enough to stick out at you. if you dont see any scoring with the boroscope then your cylinder walls should be ok. i had 108k when i pulled my motor due to #4 ringland failure, walls were not scored up.

I haven't been able to get a good image of my cylinder wall yet.

Results from leakdown test #2:

Cyl 1: 27%

Cyl 2: 23%

Cyl 3: 24%

Cyl 4: 27%

With the intake manifold and TGVs off the car I may as well do another test. Maybe this time I'll be able to hear where it's leaking.

in the pictures you have of the cylinder wall and piston the junk at the top of the cylinder wall is called ring ridge its just the area on the cylinder wall that does not get scraped by the piston. I would venture to say your ringlands in that cylinder are PROBABLY ok. When i pulled the head off my motor for the fuct ringland, the ring ridge was excessive, and comprised of nothing but burned oil sitting at the top, in a cake like consistency.

 

sorry i havent been around here lately man, started a new job.

Good info. I've been looking up pics of other EJ255's and I noticed that alot of the motors have the same sludge-type crud near the top of the walls.

What's your new job?

Say it ain't so, somebody say it ain't so...

http://images.tapatalk-cdn.com/15/12/10/9984862a57376b0e0c9c0e39ae046f10.jpg

The original crosshatching is visible all of the way around the cylinder.

The vertical lines are light and easy to miss, but there's definitely something going on there.

There are a couple locations around the circumference with vertical lines.

After dwelling on the pics for a while it looks like there's a visible crack that aligns with one of the scoring marks.

In the 6-in-1 image the crack is on the right side of each image.

I'm going to try to get the camera and a pick in there tonight and see if it can GENTLY clean the piston face to get better pics.

Should I be concerned with only cleaning that particular area of the piston?

Time to finish my build spreadsheet...

Sub'd.

I think I'm fighting the same problem here. Occasional rough idle or low idle. CELs on cyls 2 & 4 at idle or just off idle while stopped, never when actually driving the car. Engine has 130k. PO says the misfire issue cropped up 15k miles ago.

I just got this thing running after a clutch, turbo, and FMIC replacement that I chose to do because the PO's mods were not up to snuff. Planning to dyno it in a few days to tune the revised combo. Sounds like a new longblock is in my future. Don't tell my wife!

^ sounds very similar to my symptoms. Rough idle, CEL pops at or just above idle...

Kick your inner OCD into high-gear and dig through your intake system and check for leaks EVERYWHERE.

If you have the ability to log and tune, rescaling your MAF would probably help smooth out your idle. For a stock motor its a band-aid fix, but with your significant mods you may find out the car's only problem is the tune.

Sent from inner space.

Oh no worries, the inner OCD is always running . I bought the car with the misfire CEL and immediately decided to replace the turbo compressor inlet and all the intake manifold gaskets and hoses. I also did all the PCV stuff, crankcase breather hoses, TGV & intake manifolds seals, all the little fuel evap, boost sensor, and other little hoses in the front. That seemed to do the trick at first and then it popped the CEL anyway. Ignition coils and spark plugs were also new.

We'll see what the dyno tuner can pull off later this week.

^ sounds very similar to my symptoms. Rough idle, CEL pops at or just above idle...

 

Kick your inner OCD into high-gear and dig through your intake system and check for leaks EVERYWHERE.

 

If you have the ability to log and tune, rescaling your MAF would probably help smooth out your idle. For a stock motor its a band-aid fix, but with your significant mods you may find out the car's only problem is the tune.

 

Sent from inner space.