P0330 in 2019 ZL1. Any common causes?

[Alvin]

I have a 2019 ZL1 brought to me.

The car is a track car and pretty much stock other than a pulley and a rotofab intake. Making around 10psi peak. Which honestly seems a touch low to me but nothing crazy. The car has seen some serious track time. It's not driven on the road.

We ran into this code and inspected and found two melted knock sensors. This is with stock manifolds btw. Replaced,new pig tails and still have P0330. You can clear the code, make a pull. TONS of knock and instantly get a P0330 and P0324. The 330 reads to me strictly like a electrical code. open/high resistance.

My question is.. does anyone know of any problem spots in the harness that get burned up or chafed? I'm on a big time crunch to get this out of here before I take a little medical leave next week.

[GHuggins]

I guess this wouldn't be a common problem since it's been run like it has, but that is indeed a bank 2 circuit code. However if it sees a lot of knock such as having an engine problem or something like that if will still set a "circuit" related code. If you're not hearing anything and voltages don't show any shorts, I would second guess the new sensor. Might be worth swapping the two side to side and seeing if the code changes to the other bank and then if the wiring was melted it might be worth peeling back some of the insulation around those points to check closer for melted wires. Loose terminals can cause the 324 code. Heat could have just weakend something else down the line?

[Alvin]

The car came to us not running with a blown up clutch. Like car won't move blown up. I wouldn't be surprised at all if it had a issue before hand. Quite common for people to bring a car for tuning and it turns out before I even start on it it's missing or is down a cylinder completely etc.

I started on this last week. First pull with the tune he came in with showed a miss on even bank but also a TON of knock retard. I flagged it for the miss and had our shop put a set of plugs in it.

Yesterday I made some pulls and there wasn't any clear indications of a miss but still TONS of knock at WOT. That is when it set the knock sensor 2 circuit code. We inspected found melted knock sensors and replaced/fixed. It's likely it was missing still at this point but the knock sensor circuit codes and melted knock sensors had our attention. It was tripping that code immediately. Every time, repeatably. Now that is corrected and has not tripped since.

I just made some more pulls on it with the tune returned as much as possible to stock and logging misfire counters. As a diagnostic. This came to us modified, even has a flex fuel kit on it that the new owner didn't know about. So the tune is what I think is stock minus flex fuel changes, left his original DD, and my start on the MAF because I didn't want it lean. I had to ask for a stock file on this forum because the original file was modified. I should have used my knock sensor settings for the "back to stock" try but that was what I was on before hand and same issue. I've had the knock sensor levels into the 6's with no change. This is making basically stock boost. I would expect it to make a clean pull with a stock file.

I don't like to use misfire diagnostics typically but this one is slamming #8 hard. Usually will hit about 50 counts right away. The o2's show the same miss it had before plugs. Tomorrow when the car cools down we are going to do a compression test on 8 and two other cylinders to compare to. It does not miss lugging the car in 6th gear. Car isn't obviously missing in any other way than at WOT. The missing is very audible at WOT. I hear no knock. The plugs we pulled out have zero signs of real knock on them.

This has stock manifolds/cats. As I mentioned before.. clear signs of being super hot with the knock sensor connector literally melted to the knock sensor. Car has been has been used hard. It's not driven on the street. I suspect the miss is going to be a cam lobe, spring, injector, or coil. Perhaps a bad plug out of the box but I'm thinking that is not likely and the miss was there before the plug change. I would think it's quite possible he's got a bad cat although boost is a touch lower than what I'd expect with this combo. Every bad cat I've found so far has caused way more boost than you'd expect.

Mods that we know of.
Rotofab intake
pulley
flex fuel kit but filled with 93.
no mufflers.

I'll post a file from it in a second.

7stock try.hpt
miss2.hpl
As found.hpt

[GHuggins]

These LT4's are pretty resilient. I've seen them have more bottom end bearing issues than anything to do with a piston since they do have forged pistons, BUT if it's been that hot they are notorious for stretching and dropping exhaust valves. That could explain the misfiring under power too. Might be worth a back pressure check to be sure of the cats too. The new engine part would have me wondering about the electrical in general and wondering even more about the miss. Might even question the rest of the story you were told. You know what you're doing. Just throwing out what I've seen on these.

[Alvin]

Compression checked out.

It could be a wiped cam lobe or some valve train damage from over revving when the clutch exploded. We scoped the cats and they look completely fine. Put a new plug in 8 and swapped coil/wire from 6 to 8.

I hate guessing on the customers dime.

[96GS007]

Remove the oil filter and cut it open to check for glitter (or drain the oil). Wouldn't surprise me if one of the lifters went south. DoD cars seem to have a bad habit of that. Might also consider pulling the valve covers to check the valve springs.

[edcmat-l1]

If there was enough valve train damage to cause a noticeable miss I'd think there would be some noise involved.

If there was enough valve train damage to cause a noticeable miss, it should show up in a compression test. A worn intake lobe would have a lower initial "puff". The first big pump in compression. If it has a worn exhaust lobe it should build max PSI quicker than a normal cylinder. Both these effects are relative of course.

Worse case it's minutes to cut the filter open and also rip a valve cover off it and do a visual.

My bet is it's a broken inner valve spring. Probably from an over rev. That would allow the engine to run normal until the added spring pressure is needed, i.e. higher RPM in a dyno pull.

[Alvin]

Found the problem.

Weak terminal connection on the coil. not the plug wire.

Never threw a code, didn't miss any other time than WOT 4000 + RPM.

No miss, nothing on the misfire counters, no knock at all. All is good. Gonna go have a beer and tackle tomorrow morning. F*cking hot rods.

[GHuggins]

Compression will still check good with a stretched valve. Been down that road. You have to pull the covers and take the rockers loose to measure valve tip height. I'm not sure why I had thought it had a new motor when you said clutch. Gotta stop working so late Anything's possible in regard to the engine then.

EDIT - Looks like you found it. Good deal... Wouldn't even set a circuit code. That's some BS

[edcmat-l1]

Congrats on the find. Right at the buzzer. 5 pm quittin time LOL

[Alvin]

Attaching logs from this afternoon. Wild difference between the two.


FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF




hard miss 3.hpl
fixed.hpl



For anyone else reading. I've had wiped cam lobes show up completely normal on compression test. It's honestly pretty wild how often we will take apart a stock car that we can't tell has anything wrong with it but has trashed cam lobe or two. I've also never seen a wiped lobe show up in a filter. I'm pretty diligent about cutting filters open. All the broken valve springs/ bent pushrods have been very obvious to me.

One of my TBSS customers who is pretty picky (in a good way). I was trying to diagnose a random miss on both banks. If you made 10 pulls it might show up on 2. Well before we got it figured out it lost a crank thrust bearing. Before that happened he cut open every filter and didn't find anything other than normal small amount of new engine glitter. When we pulled the engine apart.. It didn't have a exhaust lobe that wasn't ate up. All 8 were chewed up.

[96GS007]

Congrats on the find!

[96GS007]

If you need new coil pack connectors, Mouser sells them....

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