Cold Start Rough Idle

[916MKIIIx2]

I've never had so much trouble ordering a common part before, I have been waiting for pepboys to get me this fuel filter since monday or tuesday damn. Let you know how it runs when I get it.

[916MKIIIx2]

Ok, So I put in the fuel filter and it helped, but did not fix the rough idle on start up. So I pulled out all the spark plug wires again took them up to wyotech and tested them, all came back good, tested all my spark plugs also came back good at both places I tested them. So I said fuck it, since I had one extra spark plug, started with replacing cylinder #1 spark plug, still rough idled, then moved the good plug to cylinder #6, rough idle went away but now I can really feel the miss fire, I almost want to say its inconsistently missing 2 cylinders... Coil pack? If I remember correctly the coil packs are 1 per 2 cylinders, get back to me please, the problems almost fixed!

[El Supracabras]

Yes, the gte uses a wasted spark ignition. The ge uses one coil connected to a distributor cap. I know 1 and 6 share a coil but dont remember the order of the rest. Its posted in numerous places. There are tests to determine a bad coil in the tsrm. You can sometimes spot tiny cracks in the plastic and epoxy on them if you just take them off and look closely at them. I've even seen the plastic surrounding the connector terminal crack and corrode inside causing intermittent misfires.
Have you checked the timing? I've noticed on many cars that prior owners/mechanics will adjust the timing to mask other problems (vacuum leaks, tune up, bad sensors,etc.), so when you start fixing those problems the timing sometimes winds up needing adjustment. My opinion is, it's always a good idea (though not always necessary) to check timing after repairing things relevant to drivability issues. Try checking it, it's free and who knows, you might get lucky.

[916MKIIIx2]

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]

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]

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.

[ochowdero]

same happened to me,
i replaced the bvsv (becuz mine was cracked, maybe this is happening to you?{its located right above the radiator, to the left if your facing the engine)
its part number 23262
http://www.cygnusx1.net/Supra/Librar...spx?F=1708&P=3
you can get this from driftmotion.com or rock auto.

i did that and it still didnt work...
i noticed my valve covers were leaking...BAM.. did a valve repair job and im on my way...

hope this helps..
also if this is an automatic car then your syncros? may be bad...people rule that out but honestly even with the valve cover repair and the bvsv it still did it abit...i did an auto to manual and i dont have that problem anymore.