Tac-tac-tac Noise = Bad Coil?
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Track Day
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Join Date: Jan 2012
Location: So. Cal
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1999 C4 - 135K miles: I started hearing this tac-tac-tac noise coming out of the exhaust on the passenger side, it was faint at first, my mechanic thought I was hearing things, but it became more pronounced. We talked about the prospect of a new engine given the high miles. The opinion I got from him and another mechanic was that the lifters were likely causing the noise + the high mileage. Another mechanic told me not to worry.
In retrospect, I wish I had recorded tac-tac-tac noise. It was loud enough to be disturbing but I wasn't prepared to buy another engine or crack mine open. It kind of sounded like the noise in these videos I found on You Tube:
More like this one:
At any rate, drove the car with the noise the last 10K miles or so... I was at a stop light this week and I felt the engine running rough at idle for an instance, minor tremor, RPMs dropped a bit, felt lack of power when started moving, it had happeded before, thought it was the clutch slipping or worse. On the way home that day, a mile in on my now short 2 mile trip home: Lack of power again, rough idle and the engine light started blinking. Shut it down for a bit, restarted and decided to nurse it home.
Had it towed to my Indy and based on my description he felt it could be a coil failure. Sure enough cylinder failure #6 showed on the code reader. $200 later with a new coil installed it runs like it's supposed to and most importantly the tac-tac-tac noise is now gone. The engine sounds great, just the way it's supposed to and there is more power. Happy camper!
I feel like a dodged a huge bullet, knocking on wood.
![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Got the car with 18K miles at the end of 2004, have 135K now still with the original clutch (I got when I bought the car), IMS etc... Replaced the coolant tank a few years ago and other than regular maintenace, that's about it. Just had the front brakes redone for the first time last month, with the tac-tac-tac noise and all.
It used to be my commutter, 70 very enjoyable FWY miles round trip to work, specially with light traffic, and with no issues. Now I drive it 2 miles to work each way.
I just thought I'd share my good fortune on this long post and hope it can alleviate some stress or provide a possible answer if you start to hear an annoying tac-tac-tac noise coming out from one of the banks into your exhaust.
Have your mechanic check the coils!
In retrospect, I wish I had recorded tac-tac-tac noise. It was loud enough to be disturbing but I wasn't prepared to buy another engine or crack mine open. It kind of sounded like the noise in these videos I found on You Tube:
More like this one:
At any rate, drove the car with the noise the last 10K miles or so... I was at a stop light this week and I felt the engine running rough at idle for an instance, minor tremor, RPMs dropped a bit, felt lack of power when started moving, it had happeded before, thought it was the clutch slipping or worse. On the way home that day, a mile in on my now short 2 mile trip home: Lack of power again, rough idle and the engine light started blinking. Shut it down for a bit, restarted and decided to nurse it home.
Had it towed to my Indy and based on my description he felt it could be a coil failure. Sure enough cylinder failure #6 showed on the code reader. $200 later with a new coil installed it runs like it's supposed to and most importantly the tac-tac-tac noise is now gone. The engine sounds great, just the way it's supposed to and there is more power. Happy camper!
I feel like a dodged a huge bullet, knocking on wood.
![ducking](https://rennlist.com/forums/graemlins/icon107.gif)
Got the car with 18K miles at the end of 2004, have 135K now still with the original clutch (I got when I bought the car), IMS etc... Replaced the coolant tank a few years ago and other than regular maintenace, that's about it. Just had the front brakes redone for the first time last month, with the tac-tac-tac noise and all.
It used to be my commutter, 70 very enjoyable FWY miles round trip to work, specially with light traffic, and with no issues. Now I drive it 2 miles to work each way.
I just thought I'd share my good fortune on this long post and hope it can alleviate some stress or provide a possible answer if you start to hear an annoying tac-tac-tac noise coming out from one of the banks into your exhaust.
Have your mechanic check the coils!