Misfires on one side 3L SCV6 2015

[master_xx]

Hi people,
The topic is frequent on the forum, but I haven't found any definitive answers. The problem is with misfires on one side within the range of 900-1100 RPM. All possible replacements of spark plugs, fuel pumps, coils, and injectors have not changed the situation. I have also replaced all low-pressure sensors and the gas station in the tank. The misfires occur, and the engine starts to malfunction, shaking, and I turn the engine off and on again, and everything becomes normal, but when I drive slowly in traffic, the engine starts to knock again. The system errors only show misfires in three cylinders on one side. Many people say that this is a problem with the ECU module that controls the engine, but I took it from another car and nothing changed. There is a possibility that the timing marks on the timing chain are not properly set. I see that this topic is frequently discussed, but I am unable to find an answer.
Thanks for all.

 

[roverzac]

Personally, the first thing I would do it check supply voltage on one side vs the other. Then, a leak down test.

These help narrow down the issue without replacing anything up front.

Which bank? Has any other work been done recently?

 

[master_xx]

Personally, the first thing I would do it check supply voltage on one side vs the other. Then, a leak down test.

These help narrow down the issue without replacing anything up front.

Which bank? Has any other work been done recently?

A row of cylinders on the driver's side. The power supply is checked, everything is fine, the tightness is also checked, everything is fine, if the vacuum were violated, there would be a very rich mixture of fuel in the readings, everything is normal there now. The car was brought from Texas, two injectors, two high-pressure pumps and nozzles were replaced. It is unknown if the chains have changed. Coils have been checked, all injectors have been checked, all spark plugs have been checked, now there are no errors in the computer, only ignition failures that do not appear every day after all errors have been reset.

 

[powershift]

Its plausible that chain slack is causing a problem because the miss-fires could be timing related at the mechanical side with the camshaft(s) instead of fuel delivery and spark delivery. Did you check the chain tension? On my V8 I stuck my finger in the oil fill and could push the chain down. It moved a bit and I could hear it or the actuators making noise at idle. After doing the chain job I stick my finger in the hole and the chain is tight asf. It didn't throw codes or have behavior problems like that but either one of your assumptions are wrong or its the chain or your mechanic(s) aren't doing it right.

 

[ebp02]

A loose ground in the front by the cam sensors made my bank 2 misfire like that, ended up frying my ECU, well at least the coil pack part of it. Ended up tightening the ground (8mm) and having my ECU cloned to a working one.

 

[master_xx]

Its plausible that chain slack is causing a problem because the miss-fires could be timing related at the mechanical side with the camshaft(s) instead of fuel delivery and spark delivery. Did you check the chain tension? On my V8 I stuck my finger in the oil fill and could push the chain down. It moved a bit and I could hear it or the actuators making noise at idle. After doing the chain job I stick my finger in the hole and the chain is tight asf. It didn't throw codes or have behavior problems like that but either one of your assumptions are wrong or its the chain or your mechanic(s) aren't doing it right.

So I'm also inclined to incorrectly synchronize the shaft on the problem side, the circuits did not change according to the machine, I'll look there soon, thank you. Because the entire electrical part has been checked and replacing any spare parts does not give any result.

 

[master_xx]

A loose ground in the front by the cam sensors made my bank 2 misfire like that, ended up frying my ECU, well at least the coil pack part of it. Ended up tightening the ground (8mm) and having my ECU cloned to a working one.

It's all been checked, everything is fine. Thank you.

 

[jlglr4]

Maybe I missed it in the above discussion, but seems like o2 sensors would be the number one suspect here. Have those been checked/changed out?

 

[master_xx]

Maybe I missed it in the above discussion, but seems like o2 sensors would be the number one suspect here. Have those been checked/changed out?

no they weren't checked, but wouldn't you see an incorrect fuel mixture if they were working incorrectly?

 

[Tapps33]

no they weren't checked, but wouldn't you see an incorrect fuel mixture if they were working incorrectly?

On mine, I was getting misfire codes every time I started up. Along with “too rich” on both banks. I started with the O2 sensors as I thought I had good MAF’s. Even though there were no O2 sensor codes, almost all my misfire codes went away. Then, I swapped the MAF’s out and all was good to go.

I’m still battling a rough cold start and then every now and again I’ll get all left bank misfires, but it appears as though I only get them when I let the engine idle for longer than 3-4 mins on the first start. Once the engine is warm, all seems good.