Midway through my third 25-minute session at a road course today (Summit Point), my car -- a 1M with 41,000 miles -- developed a "hitch" under heavy throttle and would not rev smoothly past 6,200.
Initially, it would stumble only in third gear, and at times felt like it was hitting a rev limit. Sometimes it seemed to last for 3-4 seconds, and would eventually make it way past the rough spot and resume accelerating. And sometime it would rev right on to redline without a hitch, even in 3rd gear.
After experiencing this 5-6 times, I also began to detect a roughness and loss of acceleration in 4th gear. Also, the range it which it was stumbling seemed to widen to approx. 5,800-6,200.
I brought the into the paddock to check for codes after this happened several more times over 2-3 laps. Surprisingly, according to my to-date completely reliable P3 vent gauge, there were no codes.
I suspect a failing coil pack because this only happened under heavy load under track conditions on a humid 90 degree day. Although my oil and coolant temps were fine, I figure that heavy usage and high under hood temps may have caused a tiny fracture in a coil pack. FWIW, I had no problem accelerating through the gears under far less stressful conditions on my drive home.
Although the problem could be caused by spark plugs, I'm ruling that out since they were replaced just 1,300 miles ago.
But before I fix on the coil packs (which I can replace for about $300), is there any chance the issue might be a dirty/clogged injector?
I appreciate your advice/suggestions about how I might proceed.
Thanks.
Neil
Initially, it would stumble only in third gear, and at times felt like it was hitting a rev limit. Sometimes it seemed to last for 3-4 seconds, and would eventually make it way past the rough spot and resume accelerating. And sometime it would rev right on to redline without a hitch, even in 3rd gear.
After experiencing this 5-6 times, I also began to detect a roughness and loss of acceleration in 4th gear. Also, the range it which it was stumbling seemed to widen to approx. 5,800-6,200.
I brought the into the paddock to check for codes after this happened several more times over 2-3 laps. Surprisingly, according to my to-date completely reliable P3 vent gauge, there were no codes.
I suspect a failing coil pack because this only happened under heavy load under track conditions on a humid 90 degree day. Although my oil and coolant temps were fine, I figure that heavy usage and high under hood temps may have caused a tiny fracture in a coil pack. FWIW, I had no problem accelerating through the gears under far less stressful conditions on my drive home.
Although the problem could be caused by spark plugs, I'm ruling that out since they were replaced just 1,300 miles ago.
But before I fix on the coil packs (which I can replace for about $300), is there any chance the issue might be a dirty/clogged injector?
I appreciate your advice/suggestions about how I might proceed.
Thanks.
Neil