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Discussion Starter · #1 ·
So the car started running rough at idle least week. Has a BTR 2.5 cam but instead of the normal lope you get a very consistent sound like a locomotive steam engine. I can only detect this happening at idle. Here are some things I observed.

  • If I leave it in gear with my foot on the break the idle seems to jump between 850 (normal) and around 600 (rough idle).
  • If I put it in neutral the rough idle predominantly goes away but occasionally occurs.
  • If I let off the brake and slowly accelerate it chugs for a second and then transitions into normal driving mode like someone flipped a switch at around 1,200 rpm
  • Sometimes it won't switch over to "normal" idle and when this happens it stays in first gear up to about 2,000 rpm with extremely light pedal chugging all the way. Then I let off and it will shift and go back to "normal" mode.

I still have to go out and get an IR gun to see if one of the exhaust manifold primaries is colder than the others after a cold start. I cleaned the injectors last week and it was better for a day or two but then started doing it again today. I also replaced the 'Y' vacuum line running from the CAI to the valve covers.

Any and all ideas are appreciated. I've taken it to two shops already and nobody will even look at it because it's been "modified too heavily".... This is what I get for living in central Illinois.
 

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Discussion Starter · #3 ·
Have you unplugged the maf and tried it? Also could be an o2 sensor issue maybe. No codes? Checked plug wires?
No codes. I can try unplugging the MAF to see what happens. Does it go to a default mode if I unplug it? Haven’t checked plug wires yet. I can’t get my big mitts down there to wiggle them. I’ll see if I can get my son to help me.
 

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Check wires first. Unplugging maf will use a base map. Could be a wire that's making intermittent contact and not throwing a code, or one of your upstream o2s could be starting to crap out and cause a rich condition... Headers on it?
 

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2014 CTS-V Sedan A6
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Do you have HPTuners

If you unplug the Maff it will run in speed density, which I doubt the car is tuned to run in SD.

If you don't have HPTuners, I'd really recommend you get one....and a wideband as well.
 

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Discussion Starter · #7 ·
I have headers on the car. I don’t have an hptuner or other way to watch what’s going on. My Bosch 4.9 wideband O2 dies every time I swap it out. It works for about 10 mins and then dies. Think I need to switch to an AEM 30-0330 (have a 30-4990 now)
 

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Discussion Starter · #8 ·
Just wanted to thank everyone who commented on this post. I am 99% sure I figured out what the problem is. Popped the hood while it was idling to disconnect the MAF and noticed a rather large arc between my #5 wire and the header primary. Needless to say I did some searching on the forum and bought myself a set of the Accel 9070C wires and some heat shield boots. Will be here Friday just in time to spend another weekend working on the car.

Any suggestions regarding the removal / installation of the wires? I seriously can't even get my hand down in there to reach #1 let alone 7 or 8.
 

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Pop the coils off the valve covers, gives a little more room. Not sure if you still have the hx hardline on the pass side or not but that can be unbolted and manipulated a little also.
 

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Discussion Starter · #10 ·
Aluminum360 - Just wanted to say thanks again. Was able to get the wires on without too much difficulty after taking the coil packs off. Also noticed that when I pulled the old wires off the car none of them were melted or cracked. Not sure how I was getting an arc between the #5 wire and the primary... Regardless, I put the Accel wires on and the car ran great. Admittedly the new wires feel kinda loose compared to the factory ones but they all made good connection with the plug.
 
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