mild backfire?

[DavidT]

Lately, I've notice a mild "backfire" at idle and slow speeds. It is more of an occasional "burble". It did it today while idling... about every 5-10 seconds. Anyone else recognize this. I wonder if it is associated with the X-Cal SCT programming...
I've been meaning to get to the dyno... curious to see how my car likes its new programming...

 

[Ian Macoomb]

Coil perhaps? Have you experienced a bad coil yet? A bad coil will hiccup at idle. The exhaust note also changes and is really noticeable with an open exhaust.

 

[DavidT]

I'm pretty sure I am on the original coils, I'm at 102,800 miles. Kirk swapped them at 80,000 miles, when the cams were welded.
If it is a coil, the symptom seems to be minor. Could the motor's performance be compromised this early?
Oh yeah, your right Ian, with the exhaust opened up, the hiccup is WAY more pronounced.

 

[Gen2Gen3WhatNxt]

my car is haveing this same issue. I havent messed with my coils but ive thought thats what it must be. But on a side note ive been running the xcal sct 93 program for months now. Have you tried switching to stock F program?

 

[DavidT]

thought about it, but not yet. I don't wanna lose the performance shifts!

 

[RoadSHO]

I have noticed a miss when the engine is cold. I have been running the 89 octane X-Cal program for about 3 months now. Every 5-10 seconds a small interruption in the idle. Takes about 7-8 minutes to warm up, then no problem. Does not happen with stock programing. My coils changed 20K miles ago.

 

[ornery1]

mee to and then it goes away, doug said thats normal

 

[Funmart6]

I also have a slight misfire at idle, but mine seems to happen when I have driven the car a while.

 

[Silvapain]

I'm pretty sure I am on the original coils, I'm at 102,800 miles. Kirk swapped them at 80,000 miles, when the cams were welded.
If it is a coil, the symptom seems to be minor. Could the motor's performance be compromised this early?
Oh yeah, your right Ian, with the exhaust opened up, the hiccup is WAY more pronounced.

I've had three coils go out on my car (at 112,*** miles on the odo), and a fourth one is on it's way out as we speak. You'll have a rough idle and a bit of stuttering when accellerating long before a DTC some up for a cylinder misfire. I usually just wait until it gets bad enough to set a DTC, then replace the coil in the cylinder identified in the DTC.

Around where I live (Chicago area), Murray's is the cheapest place for a coil. IIRC, it's about $70 per coil at Murray's; but it's been about 6 months since I bought one.

 

[CT97White]

My car has been doing the same thing only when it is cold & I have been running the 93 octane program from Doug for a couple of months. I just switched to the 91 octane program to see if that made a difference, but it's too early to tell. I did hear the popping at idle again this morning but have not noticed the misfire/stumbling at steady cruise or light acceleration. Next step will be to try the stock program again and if it's still doing it, I'll be looking into the coils. Mine were swapped front to rear by Kirk a more than a year ago & a couple had been replaced by the previous owner.