Hey guys Ok so yesterday as I'm driving around in the morning at about 9:30, I'd been driving around for a good 15 minutes before my car started acting funny. It started riding real harsh and would shake while I was in gear at the stoplights. Also, when I accelerated the wheel shook as did the car at around 2-3k rpms and 35-45ish mph. Then, as I'm driving more the CEL starts flashing on me and I'm like oh shit. It flashes and then stays on and my TCS comes on as well. So I take it to get the codes read and it pops up as cylinders 1,4,and 5 are misfiring. So I head out to O'Reilly to get a new set of spark plugs cause its time to replace them. I switch all 6 of them just to be sure. I go to turn on my car and the same problem is occurring as the CEL is still on. So I figure its the coil packs. About an hour ago this morning, I wake up and decide to test my coil packs just to make sure I dont need to replace all of them (which hopefully I dont). Anyways, I turn on the car and let it run for a few minutes and now its idling at just about 500 rpms. I start with cylinders 4,5,6 which are toward the radiator in the front. I was reading in another thread that if you remove the coil packs while the engine is on and see if the rpms change, then you can pinpoint which coil is misfiring. So I start with cylinder 4 and the rpms drop just a bit id say it moves a tad past under 500 rpm but still a noticeable drop. The same goes with cylinders 5 and 6 except when I removed the coil pack on 6, the CEL started flashing. So I proceed to remove cylinders 1,2,and 3. I start with 1 (rear passenger side) and once I remove it nothing happens, no rpm drop no nothing. I double check to make sure so I plug it back in, check the rpms and remove it and check the rpms again. Once again, nothing. Could this be the bad coil? I continue on with 2 and 3 and they seem fine because once again the rpms drop a tad under 500. However, once I remove cylinder 3, the CEL starts flashing as it did when I removed 6. Could this be because of the bad coil in cylinder 1 causing the others to misfire? Just to be sure I went ahead and went through each cylinder double checking again and once I pulled out 6 the CEL didnt flash like the first time and neither did 3. Now, I'm thinking that the coil pack in cylinder 1 is bad because it was the only one that didn't affect the rpms? Any insight or feedback would really help because I want to know for sure so that way I can just replace the coil pack in cylinder 1 and save some money unless it is better to replace all 6 at once. Thanks!

 

Replace just the #1 coil since when you unplugged that nothing changed.

 

Ok I'll start with that and see if the problem persists.

 

Make sure you reset the ECU after you replace the coilpack.

 

and all i got to do for that is unplug the fuses under the passenger side dash correct?

 

there is a fuse compartment on the very end of passenger side of dash
open car door to access
remove CLOCK fuse for a minute to reset ECU after each coil movement to another spot for testing,, or replacement with new coil

 

so you say to reset if after each coil movement to another spot? Should I be doing this instead of what I did earlier since I already removed each one before to test? However, I didnt move them to different spots for testing just the same spot.

 

No. Since you removed each one but at each one the idle changed except for 1 you pretty much eliminated and found the one that is bad.

 

Ok I thought so. I was just double checking because it seemed unnecessary at this point but now I see he was just putting it out there as a general tip, should have read closer lol.

 

I do that a lot..speak in general terms,,, for future referance

we used to do the `move new coil around until car runs better`,,now most just pull the power lead to coil and watch for small idle change
No change = bad coil

AFTER you do install the new coil: reset the ECU by CLOCK FUSE method-
so the system clears any codes and self test everything

NO, a code reader does not do the same clearing as a forced reset

 

So once i replace the coil, does it matter if i turn on the car or not before resetting the ecu? Or should i reset the ecu then wait to turn on the car?

 

reset ECU-to clear all codes and memory of running with a problem-

then start car
otherwise its going off bad information

 

Alright. 87$ for one coil pack... im hoping this fixes it. Ill update in a few hours once im done.

 

It worked! She runs great now much better response cause i can actually utilize the new spark plugs as well without worrying about the misfires. Im going to seafoam it in the next week here too. Fuck yea! Thanks for all the helpful tips and advice everybody.

 

$87 dollars!...where'd you buy the coil at?

 

dealer full price... plus 20% ~desperate for the part fee?!

 

Yea really had no time to search for a cheap used one and i needed it today because i had to have the car for work so i just pulled the trigger and bought it from the dealer.

 

others in need should try local parts stores for new coil, about 50 bucks

 

so got a steady CEL+TCS light on today on my way into work. sure i won't know where to start looking until i get codes read, but let's say, hopefully, it is misfiring related(& not tranny related(didn't notice anything strange w/ tranny))...which way does the cylinder number go on a '03TL ?

windshield
-----
123
456
-----
radiator

Correct?

 

thats the correct order

remember codes are clues not diagnosis--but will point you in the direction most times
If it says multi cyl misfire- buy 1 coil at local parts store and start the testing procedure to confirm which one is bad

 

yep. that's the route i'm hoping i have to go
thx