PyroSiege

I'm not sure if this is the proper place to ask about this. It can be moved if necessary.

I have an 08 LNF. I currently have a injen intake, zzp catless downpiple, zzp lower charge pipe, and Forge BPV. I am also currently HP Tuned to about 25 psi on the stock turbo.

My issue started a little while ago. After my friend tuned my car and dialed it in it was working great. No knocks, everything was perfect.

A couple weeks later I was at an autocross and around this time i started noticing some weird scratchy noise happening under high boost. I was a bit concerned so I got my friend to datalog me again. Turns out it was massive knock all of a sudden. Like it was pulling 10 degrees at times. It was insane.

After some tweaking of the tune, we found that when he reverted his cam tables back to GMS1 levels there was no knock anymore even with full boost and timing.

Since we knew it was working fine for a couple weeks we started thinking maybe there was an issue with something in the valvetrain. We still had no idea what caused the sudden change.

I tried running fuel from a different gas station to see if it was a bad batch of gas or something. That didn't help. I took the valve cover off to take a look at cams, rockers, lash adjusters and timing chain. Nothing seems really out of whack. No play in any of the rockers, The Timing chain seemed fairly tight. Nothing was at least visibly wrong.

I should mention that around the time that the knock started happening, I started noticing that the car would spew a little greyish smoke after letting off after reaching high boost. Just for maybe a second or two. And the car was idling a bit funny. It was almost like it had a miss or something. I'd rev it a bit and it would kinda sputter. But cruising around it didn't seem like anything was wrong.

We also checked the compression and everything seemed correct, above 150 and only 1 or 2 difference between any of the cylinders.

It also was throwing no codes and scanner didn't pick up any misfires or anything.
We did notice that it the idle would get rough for a second here and there. When it did, the timing would jump to -25 degrees, then back to normal for a while.

This is absolutely baffling.


TL;DR: The car has one or many problems that seem to be eluding me and everyone I talk to.
Greyish Smoke after boosting and letting off (only). Knocking when until cam tables were brought back to a stockish level. Intermittent rough idle with timing jumping to -25 for a second at a time.
Compression good, Spark plugs new and gapped correctly, Coils are all stock.

Anyone have any insight?

I'd appreciate any ideas on where to look.

tomj77

iTrader: (2)

u do leak down test? I don't think gray smoke is anything to worry about. gray smoke is normal. did u check for turbo shaft play? scratching sound sound like u may have some, if so, replace turbo. other than that, id think maybe a sensor went out. maybe cam position sensor or something, I don't know much about what issues that causes maybe someone else can add

Sl0wbaltSS

Blown turbo. Check for shaft play and most likely smoke coming from turbo. As of the knock, for autocross you should run richer to keep your engine cool.

PyroSiege

Turbo Shaft play seemed no different from other KO4's I checked. They all had a tiny amount of play, but mine was no more obvious than any that had no issues.

That's kind of irrelevant anyway. I'm planning on upgrading the turbo soon. So if that is the issue with the smoke, then it should be resolved. I'll post if that was the issue.

blueLNFftw

iTrader: (16)

Any more luck?

08VRSS

Not trying to be a dick here, but how competent is your tuner? Playing with cam tables, boosting 25psi on a K04, etc.... Hopefully this is not SSkev's work, he seems to be a good tuner.

PyroSiege

No luck yet, but I was starting to think a sensor may be going, but still no codes happening.

I'll let my tuner know that I'd like it to run a little bit richer for autocross. That actually makes good sense.

As for the tune. I don't think it's an issue of the tuner, because it was working fine with no knock while we were datalogging and tweaking the tune. It just seemed to happen one day. Definitely seems like something went bad. It's just really hard to find it.

I'm going to be replacing lash adjusters here pretty soon and walnut blasting the intake valves. I heard both of those things can cause some issues I've experienced.

After that we can try other things if it's still acting up. Maybe try replacing some sensors.

Sl0wbaltSS

Check the bottom of your intercooler or bottom of your lower charge pipe, see if it's full of oil.

ECaulk

iTrader: (6)

Don't listen to this guy for tuning advise or repair he knows very little about the LNF and tuning You shouldn't be running a 25psi tune for auto-x its not needed, you more than likely should be in 2nd gear and never shifting. A solid 19-20psi will net you enough usable power for auto-x. If you're road racing dial the tune back down to hold 22-23 and you should be commanding much more than 14 degrees on 93 in the high load section. Also make sure your LTFT are within +-2, with the preferred to be -2 since the ECU is then taking fuel out.

Also the knock you observed was it actually pulling timing (check the log out to see if the advance decreased) or it the ecu just saying knock?

Check your evap system also, remove the tube from the front solenoid if there is pressure there you need to replace the in tank and front pieces.

08VRSS

Some good advise above me there, 25 psi is a bit high for the k04 even for a street tune. I tune for 20 psi for auto x is plenty and i go for about 21-22psi psi for drifting on my cutomer's sky redlines and 21 psi for road racing. Gotta keep those IATs down. LTFT i like to be about 1-2% negative so its taking away fuel a bit. 14* up top is super safe timing on 93 though, i run that up top on my personal car on the ZFR, .88 lambda on the hit, tapering to .87 and .86 up high if you're going with aggressive timing. Your tuner does not sound like he knows what he's doing so be careful. Another tuner in Houston had some bs tune that melted two pistons and broken some ringlands on his customer's car recently and he is well known. Be careful of who you let tune your car man.

ECaulk

iTrader: (6)

Only reason I was saying 14* was to keep the egt's down a bit (in theory it should don't have my egt gauge installed yet to verify, but once I do I'm renting a mustang dyno for a day and having some fun)

PyroSiege

There was a bit of oil/goo that came out when i replaced the lower charge pipe. it was pretty nasty. My car seems to have a fair bit of blow by, but I have good compression and good power.


I raced with a trifecta tune at 22-23 psi and it was good and all, but the tune as is right now feels way better. Much smoother and a bit more power boosting higher. I like autocrossing, but It's a lot easier to go to the drag strip and have some fun where I'm from. I only do an AutoX once a month or so, but Drags might happen a bit more often. Hence why the higher boost tune.

I mean I have HPT now, so i could have a couple tunes that I switch between as needed, but I think the boost level of the tune is irrelevant for AutoX. It's not often that I'm actually going full throttle so even if I dropped the boost I wouldn't really be hitting peak boost anyway. (The AutoX we do where I live seems a little different from AutoX i see in other people's videos. Our courses are usually quite tight.)

My tuner knows what he's doing, he has basically done what you guys are talking about. This is an issue of something broke. I've been driving my car hard for over 120,000kms. Drags, AutoX, Road Course. I mean, things WILL break. haha. I have no issue fixing it, but I need to figure it out.

I recently did the walnut blast on the intake valves. and the car definitely runs smoother at idle and low revs. Totally worth it. But the odd idle issue is still there. Almost sounds like a vacuum leak, but inconsistent. Sometimes it will idle just perfect, sometimes it will sputter a little or drop idle and recover.

Also, the smoke after boost is still happening. I've heard a few theories. 1. My turbo is going. 2. I could be the Valve Stem Seals, and 3. It could be a leaky injector.

If it's the turbo, I'm planning on replacing that soon anyway, so I'll wait and see what that does.

PyroSiege

So, turns out it's a burnt or damaged intake valve. Gonna need to rebuild the head. Leak down had air escaping through the intake. Just incase anyone wanted to know. Thanks for the advice all.

Sl0wbaltSS

PyroSiege

Ok. So I forgot to update this post. Didn't want it being left without the actual resolution.

Turns out it wasn't the turbo or the valve seals. It was a broken ringland. Cylinders 1 and 4 had broken ringlands under the first compression ring.
It finally have up the ghost and compression was:
#1=120 #2=130 #3=140 #4=30.

After i got the pistons out there was a chunk broken on cylinder 1 but still in place. Cylinder 4 had about an 1/8 of the way around the piston missing, yet the top of the piston was completely unscathed, i have no idea how that happened, but it did.

Long story, short, i replaced the motor with a used one. With the idea of rebuilding the other one at some point. While taking it apart i noticed all this.
​​​​​​
I've seen this happen to a couple people lately so I just wanted to clarify.

Oh and as for the supposed air leak on the leak test? That was my stepdad doing the leak test wrong...

63 Nova SS

iTrader: (3)

Ringland failure has happened to lots over the years. Sorry to hear it got you also. Are you sure your tuner knows what he is doing?