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hey guys, got a 07 escalade with the 6.2l v8. its got 335,000km on it and has been running great, never had any engine issues other then the piston slap and noisy lifters
so i have noticed that over the past 50,000 km the truck has had this problem but back in the day it would only do it if i let the truck idle for 4-5 minutes (which i rarely would ever do) and it just gradullay got worse and worse and now it "misfires" at idle within 15 seconds
so the thing is whenever i come to a stoplight and stay stopped for like 15-20 seconds, ill get the message that says " stabilitrak off service traction control" and then the tone of the engine will change and i guess it will sound rougher with a shake, but right when i start driving agian it goes back to normal and then message clears. if i go on the highway, it drives perfect, smooth, good power good revs and never triggers a messsage or anything, but when i come a stop light or any stop, if i wait long enough it will do its thing again.. rough idle, stabilitrak message, and also if i wait like a minute or 2, then the check engine light starts flashing as well, i believe this is because the truck thinks its misfiring or is misfiring and thats why the check engine light flashes.
firstly, the codes i get are p0308 so i know there is a misfire
P0036 HEATER CONTROL CIRCUIT BANK 1 SENSOR 2
P0056 HEATER CONTROL CIRCUIT BANK 2 SENSOR 2
P0449 EVAP EMISSION SYSTEM VENT VALVE/SOLENOID CIRCUIT
P0452 EVAP PRESSURE SENSOR/SWITCH LOW
P0308 ENGINE MISFIRE CYLINDER 8
i also do have some evap codes but have had those forever
so im not a mechanic on my own but i swapped coils and tried to see if the misfire stops and it doesnt. i also swapped the plugs and wires around and still has the same problem. the plugs and wires are relatively new only 50,000 km on them. i used my code reader and traced it as a p0308 so i swapped a brand new spark plug into that cylinder and still has the same problem. but have showed it to a local indie mechanic and he did a leakdown test got 6% so he said the engine is still strong, he said compression test was above 200+ for all cylinders, lastly i believe he said he changed the intake manifold gasket but it still has the same problem. i am assuming he checked the fuel injectors but if not, i guess thats the first thing i should try?
anyone have any luck? i was reading more and someone said when the engines get gunked up and old, the vvt goes wonky and ends up causing this? but not sure if thats the truth