The engine runs rough and sounds horrible when im at a speed that engage overdrive. Ive searched high and wide for anyone thats solved this issue. Ive seen to replace the COPs but that didnt seem to fix the issue. The engine has around 40k miles and the trans about 30k. Both are remanufactured and dont have any other issues. I cant remember very well but im fairly sure this same issue existed before i swapped the engine and still persisted when i swapped the trans. Any insight or steps to remedy this issue is greatly appreciated.

 

The most typical solution for this symptom that appears at 45mph is new spark plugs to clear the misfires under load.

If you have an OBD2 device that reads live data you could confirm this by.checking the misfire monitors.

 

​​​​​​​I have changed the spark plugs and it did not change anything. I also have a Forscan device and have absolutely 0 Misfire counts. One thing i found odd was when i changed the spark plugs the ground electrode appeared to be damaged/melted away. This didnt seem to cause an issue with the spark or cause any misfires

 

Is your exhaust open and breathing good ?

 

Yeah exhaust is fine. It's an aftermarket(by the previous owner) true dual exhaust. Currently straight piped but there was no difference in performance or anything with mufflers on it

 

Any DTC's ?

 

I've got a few that recently popped up. Caused by unrelated issues tho. P0430 and 420. P0011 cuz oil got into the vvt solenoid connector. I've had both issues before and fixed them. The o2 sensors come into contact with the exhaust and burn out the wiring so I've got to replace those. The oil killed the sensor I believe as it has before so I need to replace the sensor on the passenger side. I've had the issue with the 45mph rough running regardless of codes or not. There was about a year where I was free of dtcs and the issue still persisted

 

Does the CEL flash when running rough under load ?

 

No it does not. I've tried various time lengths of driving while its running like this and nothing like that

 

I think I found a bad knock sensor. Pull that up on forescan and see if the numbers are different or if they match each other on both knock sensors under live load. Or just record your drive and review it later