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Discussion Starter #21
Swap the 1 3 5 coils with the 2 4 6. See if the misfire follows the codes. I would never have used noname Duralast coils myself.[/QUOTE]

I tested the circuits with a multimeter and they checked out, Normal readings. Good grounds and steady 12.1V power, ECM Comm wire I didn’t know how to check that. I’m wondering if it isn’t a clogged Catalytic Converter, haven’t tested injectors yet. I’d rather replace injectors than the Cat. From the prices I’ve seen
 

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Discussion Starter #22
*****UPDATE*****

So, I was able to get a MACTools Diagnostic system on the car, misfire codes were obviously still there, with the Key on and engine off the TPS location read 28% meaning it wasn’t closed. So relearned the tps to zero and fired car back up, still had misfire codes, decided to start checking harness where the TPS tied in at, found a short with one of the Cam Sensors, wiggle the cam sensor connector and the cars Idle would increase, and the TPS would make a “gear grinding” sound. Decided to pull up the cam sensors and counter and the bank 1 exhaust wasn’t reading, did some swapping around and got it reading. Wiggle connections again and idle did not fluctuate. Checked Catalytic temps and bank 1 was same temp as bank 2. Took a piece of card board and help up flat to driver side tail pipe, and it would push it away from tail pipe, do it to passenger side and the cardboard was trying to suck into the exhaust. This is where it got weird. Cleaned up the Camshaft Sensor, from all the grime and deposits and reinstalled again. Fired it up and it idled smooth, did exhaust test again and still one pushing air out other sucking in, but only codes thrown now are crankshaft Position circuit, and cylinder 3 misfire.?? Any ideas on cause of this?
 

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Cline162 , your post (quote below) is my exact problem. 2007 Ly7 cylinders 1,3,5. Been working on this a long time. What was conclusion with your engine? Did you fix it?

spark plugs so I changed them. And when first trying to start it it didn’t start at first, on the second try it started but didn’t stay running, third time once it started I gave it a little gas and right afterwards, that’s when the 1, 3, and 5 cylinder misfire came up, and the cars idle was very rough and shook the car, wants to die if throttle isn’t feathered to bring it out of the low rpm idle. If I keep it running by giving it gas and keeping it around 1800-2200rpms the CEL starts to flash and ding, and after about 30 seconds of that it goes to limp mode, “Safety Mode Active/Power Reduced” could it be a shot catalytic converter from the initial attempts of starting after the plug change?!
 
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