`14 Camaro SS M6 running rough

[Lavazen]

Hello,

I`m new here, so please treat me right
Also I`m not native speaker, so please don`t judge me for my English

A new for me 2014 Camaro SS M6 is acting pretty strange
The car had all kind of erros on the dash because the previous guy, who worked on this car, unplugged one of the ЕCM connectors, while the battery was still attached.
Some of the errors were so called "permanent", so I made the universal drive cycle and the "permanent" errors dissapeared, but 2 stayed - U0401 and Missfire Detected
Regarding U0401 - as I know - this error is more likely to be on a Auto car, but not on a manual - correct me if I`m wrong.
Also checked the grounds between the engine and the body - dissassembled - all looks good - assembled again.
Car is starting every time I hit the key, but its runnng very rough.

So, what I did till now:
1. Drove the car for ~40km at different RPM and speed. It reacted pretty strange - in one moment it is almost allright and seconds later loosed power and started to shake. - the log will be uploaded. As I am pretty new to HP Tuners and all the info that it provides I am not sure if everything looks alright, so please guide me.

2. I have a FLIR (thermal) camera on my phone and used it to check if there is any difference in the temp on every exhaust port and also at the rear of the car at the tail pipes - here comes the strange thing - looking the engine - I am completely sure that cyl. 1,2,3,4 (the most front 4 cyls) are hot and cyl 5,6,7,8 (the cyls in the back) are barely working. Also looking at the tail pipes - the drivers side seems to be hotter than the passenger side.

3. Then replaced spark plugs and wires with new - started the car and in the first 30sec it sounded OK, but the engine was still shaking, minute later and it was sounding as before .
4. Then decided to change the coils on drivers side - coils from 1,3 (the hot cyls) was placed on cyl 5 and 7, just to check if failed coil caused that - started the engine and it was all the same - cyl 1,3 were hot and cyls 5 and 7 colder as before.

5. Checked the compression: Cyl 1,3,5,6,7 - 145psi, Cyl 2 - 125psi, Cyl 4 rised to 145psi but in 5 seconds it dropped to 70psi (tested 4 times), cyl 8 - I was not able to reach it with the hose for the compression meter tool as it is cold here right now and I could not bend the hose enough so cyl 7 was impossible for me.

Anyway - somewhere between all the tests something grabbed my attention - drivers side catalityc converter was glowing red. Immediately checked passenger side and it was fine.
As I know - Cat is glowing red when it`s clogged or when there is raw fuel from not working cylinder.
Then I have decided to take out all injectors and to take them to my injector doctor just to flow check them - they are performing all equal.
Then I checked the fuel pressure on the rail - 59psi@idle but when I shut it off and came back after 30min and it was 48psi -I suppose this is OK.
Right after that I have decided to take of the valve covers and to start the engine to see if every rocker is moving as expected and they are OK.


So please check the attached log and tune files and give me some understanding what could be wrong.

Thank you in advance!

Best regards,
Tomа

[dhoagland]

Looking at the log only, Not considering your possible dead cylinders...

I think you need to look for a vacuum leak, look at the end of your log, you are idling and your MAP is 71...
Maybe this could be a sign of a clogged cat too...

Almost all of this log you are in open loop fail, the few parts you get into Closed Loop your o2's are extreamly slow switching and are mostly lean...
Also I have a screen shot where RPM seems steady but TPS, MAP, MAF, and Timing are jumping all around, seems like you might have electrical issues too..

[Lavazen]

Many thanks dhoagland,

I will focus on what you have said and make another run starting from cold engine.
I forgot to mention that the glowing cat situation was found after long idle run, so may be it is good idea to check it after some driving.
Regarding the engine grounds - the only ground I found is bolted to the front of passanger side head and the other end is bolted to the console that is holding the ABS module. According to my understanding the engine ground should be fastened to some hard metal and not a flimsy ~1.5mm thick console...
Is this the correct location of the engine ground and is there some more I can look for?
One last thing - is it possible the original owner in US to have changed the cam with something more aggresive and this to be the main reason for the engine to behave like this. I know that when the car came here in Bulgaria (Eastern Europe) it worked like a charm and it was very fast but down the road some errors appeared on the dash and someone decided to run new calibration from the ACDelco site....

Best regards,
Toma

[dhoagland]

Cam upgrade is possible, but even then I would expect the o2 sensors to function properly. Before all the issues how did the car idle?

Yes your grounds should be metal to metal. You could run a temporary heavy gauge wire from your main battery ground to a good ground on your block for testing purposes.

I can't seem to get past the Catalytic converter, here is a link to testing with a vacuum gauge and exhaust back pressure gauge.
These tests might be quicker than running test wires.
https://axleaddict.com/auto-repair/H...ytic-Converter

I believe the scanner has the ability to cut cylinders individually to try to isolate one dead cylinder

[Lavazen]

Previously tried to disable cylinders one by one, but I found no difference
Also hooked 1/0 gauge from the negative terminal of the battery to one of the heads, but it changed nothing.
I was ready to take it out for a test drive with the HP Tuners to log it, but once I fired it up I saw that the vacuum is somewhere in the 60ties area, so I shut it off and removed the intake to check if the gaskets look OK and then I think I found the culprit.
It seems that some excesive heat has deformed the runner on cyl 8. All other ports looked fine but this one was shot - the inside of runner for cyl 8 was also melted.
Then I called one of my friends to bring his compression tool which is with much softer hose than mine. Checked cyl 8 and there was zero compression.
Considering this - I believe that the intake valve is damaged so when cyl 8 is on ignition actually the flame exits the chamber and find its way in the runner of the intake.

Also - one of the attached photos shows the back of the throtle body - Is it moisture... or coolant...or...I don`t know.
What are your thoughts on this - how these droplets formed there?

Many thanks for your help, dhoagland!

Cheers,
Toma

[dhoagland]

Really not sure on the TB...

But yes, I believe you found it... Wish it was something a little more simple...
The burnt valve would explain the MAP jumping all over the place and that was probably causing your timing to follow along...