Engine Rough Cold Start

timjimmy

Active Member
Jul 7, 2013
215
12
29
Clarksville, TN
I have an '06 GT with Kooks headers, catted x-pipe, Detroit Rocker cams, FRPP intake and throttle bottle, C&L Racer intake, Brenspeed 93 octane tune, and Performance Automatic 2800 RPM torque converter. For about the last 8 months I've had an issue where, when starting the car in cold or wet conditions, if I shift into drive without letting the engine idle and warm for several minutes the engine will die. It then requires throttling the engine to get it started and it runs rough, requiring me to feather the throttle for a few seconds until the engine smooths out. Today, in sunny, 50 degree conditions, it took me probably a dozen starts before the idle smoothed out and I could take off. This time, the engine would even choke and die in park unless I throttled it. Upon starting, it would release a cloud of smoke and the exhaust had a pungent, sharp smell. It will also smell slightly of fuel. Ordinarily I would think it was a fuel issue, but I'm not getting any check engine lights. Could this be an issue with the tune? I'm running stock style flags with stock gap, and factory injectors and oxygen sensors.
 
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cmann

Member
Nov 26, 2014
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6
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Have you cleaned your throttle body lately? A dirty TB can cause all kinds of idle and drivability issues.
 

racerraj

Founding Member
Dec 17, 2001
482
30
39
Dickson, TN
Tim, My 06 GT is stock and does that, though maybe not as much. It was worse with the factory plugs. I run Champion 7989s and it got better. When it started doing it again I pulled the plugs and closed the gap some (Seems like I went down to .043, but I will verify. Anyhow, it does it less with a tight gap.
 

timjimmy

Active Member
Jul 7, 2013
215
12
29
Clarksville, TN
Have you cleaned your throttle body lately? A dirty TB can cause all kinds of idle and drivability issues.
It's only about 8 months old, but I'll pull it and check.
Tim, My 06 GT is stock and does that, though maybe not as much. It was worse with the factory plugs. I run Champion 7989s and it got better. When it started doing it again I pulled the plugs and closed the gap some (Seems like I went down to .043, but I will verify. Anyhow, it does it less with a tight gap.
I put Champions in during August 2013, but I'll check the gap.
 

timjimmy

Active Member
Jul 7, 2013
215
12
29
Clarksville, TN
Sounds like a problem with the tune especially for cold start, open loop operation.
That makes sense. It seemed like an O2 sensor problem except it hasn't tripped any codes. I'll give Brenspeed a call after the holidays. Come to think of it, it did start back in March when I installed the newest tune with the manifold and throttle body.
 
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