Cold Start Rough Idle

916MKIIIx2 · 06-01-2011, 05:47 PM

I was able to check the main coil on the coil packs but after reading there is a secondary coil inside that is... uncheckable, or atleast I can't figure out how to check the secondary, after checking the mains they tested good.

Doesn't feel like a timing issue but im no pro, its next on the check list.

El Supracabras · 06-01-2011, 07:04 PM

The secondary winding can only be checked using an oscilloscope as far as I know. There is also a device that measures Kilo volts using an inductive clamp somewhat like a timing gun. Though i'm not really sure if it will tell you if the coil is bad, only that there is increased or decreased resistance to current inside the cylinder. I'm sure someone here knows more about it than myself. Hopefully they will comment. Definitely one of those cases where having a known good part to swap or compare would be useful.
You shouldn't use the "feel" method especially with a computer controlled car. The computer can change the "feel" by adjusting fuel and timing to compensate for discrepancies (issues, driving habits) even while you drive. They are surprisingly active little boxes for the technology. The only way to know for sure that the timing is correct is to actually check it which is very easy. It may not be the cause of your problem, but it would be free to eliminate it as a suspect. Also make sure the crank pulley is in good condition, a worn and shifted pulley will throw off the timing mark.

Sonyps307 · 06-01-2011, 11:54 PM

Check the cold start time switch can cause this. Mine is doing the same thing now and I already replace every vacuum line on mine so on to the next thing now.

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06-01-2011, 05:47 PM	#1
916MKIIIx2 3" Exhaust Join Date: Nov 2008 Location: California Posts: 152	I was able to check the main coil on the coil packs but after reading there is a secondary coil inside that is... uncheckable, or atleast I can't figure out how to check the secondary, after checking the mains they tested good. Doesn't feel like a timing issue but im no pro, its next on the check list.

06-01-2011, 07:04 PM	#2
El Supracabras 3" Exhaust Join Date: Feb 2010 Location: Chicago Posts: 240	The secondary winding can only be checked using an oscilloscope as far as I know. There is also a device that measures Kilo volts using an inductive clamp somewhat like a timing gun. Though i'm not really sure if it will tell you if the coil is bad, only that there is increased or decreased resistance to current inside the cylinder. I'm sure someone here knows more about it than myself. Hopefully they will comment. Definitely one of those cases where having a known good part to swap or compare would be useful. You shouldn't use the "feel" method especially with a computer controlled car. The computer can change the "feel" by adjusting fuel and timing to compensate for discrepancies (issues, driving habits) even while you drive. They are surprisingly active little boxes for the technology. The only way to know for sure that the timing is correct is to actually check it which is very easy. It may not be the cause of your problem, but it would be free to eliminate it as a suspect. Also make sure the crank pulley is in good condition, a worn and shifted pulley will throw off the timing mark.

06-01-2011, 11:54 PM	#3
Sonyps307 Lexus & 550's Join Date: May 2010 Location: Baltimore Posts: 526	Check the cold start time switch can cause this. Mine is doing the same thing now and I already replace every vacuum line on mine so on to the next thing now.