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Charged A/C yesterday and after about 10 miles of driving the car started acting funny…upshifting then downshifting between 3rd and 4th, eventually started losing power (with or without A/C on), barely made it through my driveway to park it and overall just started running like crap. Then it started making this odd knocking sound that is loudest around the front of the engine/around the exhaust manifold. It doesn’t do it at idle, only when you press the throttle and as soon as you release it goes away. I poked around with a screwdriver to my ear and didn’t hear anything out of place. Oil is clean even after about 2K on current oil change, and is at the correct level. All other fluids are clean. Trans fluid is clean, smells fresh. Everything in the ignition and fuel system is new. I only use top tier gas. So far I have told it could be: cracked/leaking exhaust manifold, rod knock, spun bearing or some other internal catastrophe. I have spark on all 4 plugs. Had the valve cover off recently, everything inside was tight and spotless. Also replaced oil pan gasket recently, everything in the bottom end was also tight and looked very good for its age. Not sure what to do or who is on point with their guess. Also I don’t believe the A/C had anything to do with it, that was just the last thing I did before this mess. When you turn the steering wheel, or if the cooling fan comes on or I turn the A/C on while it is idling, it tries to die.
Here are some videos to show you what I’m talking about:
https://www.youtube.com/watch?v=awe2hTr1-Ac
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Could it be just a really bad exhaust leak or cracked exhaust manifold? Hmm… let’s think this through. If there is a severe exhaust leak, it can actually suck fresh air into the exhaust stream, leaning out the O2 sensor, causing the computer to richen the mixture. Maybe, but without a scan tool to see data we can’t be sure that is what’s happening performance-wise. Exhaust noise can sometimes sound like a rod knock though.
Also, an exhaust leak might explain that weird tailpipe sound in one of your videos. That video by itself makes it sound like your car is running on 3 cylinders, but that can’t be the case. The underhood videos have your engine idling way too smoothly for that.
Took the manifold off. Here are some interesting pictures…
So how bad of a leak is that? :whistle:
Everything in the exhaust (except for the manifold) is new. I installed the pipe that connects to the manifold and used a brand new gasket myself…when I was taking it apart just now, I noticed the nut on the side with all the soot was somewhat loose. So now I wonder…was it actually sealed and then eventually worked its way loose and started leaking, thus causing my problem or was it leaking the whole time without me knowing and I still have another problem? Guess I need to get a new gasket, put it all together and see…
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