[SuperSound]

Originally Posted by Goal seeker

Pulling a plug wire would trigger a CEL because it's going to pick one up every other rotation. Do you think the EMS would react as fast on something that happens intermittently, and only when it's cold? My wife had a 2014 Grand Cherokee with a cylinder head problem that was notorious on the 3.6 Pentastars. I noticed a misfire a number of times before the CEL actually came on. Different make, different reactivity?

It's definitely fast enough, the question you meant...is it enough to trigger a code. Here's the code it would trigger and expectations generally:

"If the percentage of the increase or decrease in revolutions per minute (RPM) is between 2 percent and 10 percent, the Check Engine Light will come on. If the percentage of the increase or decrease in revolutions per minute (RPM) is greater than 10 percent, the Check Engine Light will blink on and off, as to alert the driver of a more serious misfiring problem. The P0300 trouble code indicates that there is a misfire in random or multiple cylinders."

Think about the programming for a sec. Based on the OP's description, if it happens that infrequently it's probably less than 1% in the 5-10mins when the engine is cold and running it's cold start program. To an engineer, that is not a problem. The problem would occur if it did not stop and continued which would trigger a code. Remember these cars are turned for emissions even under cold start. What some think is a miss could simply be the program adapting the timings/fuel, etc... as the engine temp increases.

But I have an even better reason to tell you not to worry, I've had 3 DI cars back to back. A VW 2.0T, BMW 2.0T, and now my LT1. Guess what, all 3 have this same issue on cold start. There are even threads about it on the BMW forums with lots of convinced it was a miss...only to spend months with their car in the shop and no fix. Then come to find out they were all new to DI. Some even noticed it on other DI cars they drove but assumed BMWs were perfect and shouldn't have this issue.

I won't sit here and tell you it isn't a miss. Instead I'll assure you if that is the only time you notice it and it doesn't trigger a light then you really have nothing to worry about. The engineers programed the conditions to trigger a code for a reason. Anything less than 2% isn't an issue.