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Discussion Starter · #1 ·
Has anyone who installed the full exhaust developed a rough idle/CEL? Had a performance shop (RRT in Northern VA) install my system on Monday and the detailer that now has the car says it's idling odd and CEL is on (not blinking). The only thing that comes to mind is the shop that did the exhaust broke the downpipe stud (crummy metal) and consequently had to install a new stud which may have inadvertently caused an issue somewhere OR the rear o2 sensor wasn't installed properly/damaged. No scan yet so I don't have codes on hand. Help would be appreciated.

Auto Abarth, crosspipe, midpipe and muffler delete installed.
 

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Discussion Starter · #3 ·
I would bet they damaged the O2 sensor in someway during the install...the code will definitely point the way...
Sounds most likely, hopefully nothing too serious otherwise. To your knowledge, would damage to the rear O2 sensor cause a rough idle?
 

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The sensor after the cat is like a sanity check for the cat...it may cause a rough idle...don't know for sure how the ECU reacts to it...Greg and Brian should know for sure... I can't think of anything else that they should have unplugged or damaged when doing this job...I installed my system and know how it goes on pretty well... the only other thing is if it did have an exhaust leak close to the cat somewhere...interesting...
 

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Discussion Starter · #5 ·
That's what I figured. Crossing fingers they didn't remove the downpipe to repair/remove the broken stud. That would only increase the possibilities of screwing something up. :D Eager to hear what Brian and/or Greg may have to say about this.
 

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I'm thinking you have an exhaust leak at or near the cat.
 

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Discussion Starter · #7 ·
I'm thinking you have an exhaust leak at or near the cat.
It's very possible there's a leak where they installed the new stud, that was one of my first assumptions. I know that would trigger a CEL but would it also link to a rough idle?

I wish they just scanned the car before closing up, haha.
 

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It's very possible there's a leak where they installed the new stud, that was one of my first assumptions. I know that would trigger a CEL but would it also link to a rough idle?

I wish they just scanned the car before closing up, haha.
Yes, I believe an exhaust leak could cause a rough idle.
 
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Discussion Starter · #9 ·
I guess I'll have to wait and see until tomorrow.

Odd thing is, the CEL didn't show up until after a few cycles. First pickup showed no symptoms, only until today did they give me a call. I'll keep the thread updated as I get new info, but fingers crossed it's something minor.
 

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upstream 02 sensors are used to determine air/fuel ratio and could have an effect on running but not too much but would certainly set a light. downstream o2 sensors are only used to verify that the cat is doing it's job properly, so will set a check engine light but won't effect the running. an exhaust leak before the cat would cause a running issue as the pcm would be confused with the extra air throwing off the upstream o2 sensor, the car would try to dump more fuel to compensate and then be too rich to run right.
 

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Discussion Starter · #11 ·
upstream 02 sensors are used to determine air/fuel ratio and could have an effect on running but not too much but would certainly set a light. downstream o2 sensors are only used to verify that the cat is doing it's job properly, so will set a check engine light but won't effect the running. an exhaust leak before the cat would cause a running issue as the pcm would be confused with the extra air throwing off the upstream o2 sensor, the car would try to dump more fuel to compensate and then be too rich to run right.
So the performance shop that did the exhaust work pulled OBDII data and found no codes. Unfortunately for me now, they say the car won't start. RRT (exhaust shop) said they didn't touch anything electrical besides the o2 sensor so it sounds like there's a bigger issue at hand.

And for the record, no issues before any of this work was done.
 

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Discussion Starter · #14 ·
Well, drove down to the shop and the car most definitely doesn't start. Cranks really well but just doesn't turn over.

At a loss right now. Taking the car over to the performance shop so they can take a final look before it goes to the dealership.
 

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I'm finishing my exhaust install tonight after I had the downpipe out of the car to replace a broken stud. I'll let you know if I have any issues. Both the pre-cat and post-cat o2 sensors had to be removed in order to get the downpipe out. I wouldn't imagine that damage to either of those would cause the car not to start at all, but who knows. I'm guessing you're having a non-related issue, or maybe something else was broken during the exhaust installation.
 

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By the way, did you try to unhook the battery and pump the brakes a few times? Maybe a reset of the ECU would get it to start again.
 

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Discussion Starter · #18 ·
So minor update. Got the car towed to the dealership but unfortunately they won't be able to take a look until early next week.

I tried a few things, unplugging the battery and depressing the brake. Checking the fuses (don't think I checked the fuel pump fuse ironically). Car cranks really well but just doesn't turn over. Can't see if CEL is on because it won't start. Exhaust shop scanned for codes but didn't find anything. He did say the tool he used may not be able to pull everything. Very frustrated, what turned out to be a simple install has quickly turned into a nightmare.

Brandon, that article seems very similar to my situation. It's very possible it blew the fuse, I just wish I remembered to check it lol.
 

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Discussion Starter · #19 ·
I wouldn't imagine that damage to either of those would cause the car not to start at all, but who knows. I'm guessing you're having a non-related issue, or maybe something else was broken during the exhaust installation.
This is my thought too, but the timing is so perfect. It went from running fine to a rough idle to just not turning over whatsoever.

I really can't imagine they could have possibly damaged anything else down there besides the O2 sensor. To my knowledge that's all that's in the area.
 

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I have seen cases on the 500 Abarth where someone would pinch a wire right through the insulation causing it to short to ground and blow a fuse, or fuses. This can cause the issues in this thread. I would start by checking the fuses very carefully.

Greg
 
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