Good day everyone. New here, and was hoping to get some help and insight with your expertise!

Some background: I have a '99 TL with just over 250K miles. I'm fairly mechanical, and do most of the work on my own vehicles. This TL was my father's, and I inherited it when he passed away a couple of years ago. He was very mechanical as well, and the car has a lot of his personal touches in it.

The car was running quite well up until one day last week. It started perfectly as it always does, and I allowed it to idle for about ten minutes, as it was about 20 degrees here, and I wanted a little heat to start off my commute to work. I didn't notiice any issues on start-up. As I backed down the driveway and started accelerating down the road, I noticed problem right away. The car was shaking pretty intensely and felt sluggish. I allowed it to get up to operating temp, and the problem persisted. I then got a steadt TCS light, and flashing check engine. I was having active misfiring, and turned around and went home.

Finally got around t o checking the codes today. Misfire codes in cylinders 1, 4,5, and 6; along wiht the multiple cylinder misfire code (p0300) and a p1259 code. I tested the coil packs on the problem cylinders with a volt meter, and they seemed to be functioning. They all read around 2 ohms. I've done some research already, and a lot of people have had this same issue, changed out a coil pack, and the issue waas resolved. Is it possible that even if the coils seem to have tested good, that one of more are still in fact bad? Could one bad coil caue that much of a disruption, and a CEL reading of multilpe cylinders misfiring? IF it is not the coil/s, what are some other possibilites that would cause such a sudden disruption like that?

Any ideas help! Let me know if there is any other information I can provide that may help you!! Thank you!

 

i had similar: horrible shaking and sluggish car, multiple misfire codes, and the flashing check engine light. In my case it was a single coil pack. I narrowed it down by disconnecting each coil pack's electrical connector (one at a time) while idling and if the idle doesn't change that's the problem coil pack. Give it a shot. Your problem could be one coil or multiple.

but i didn't get the p1259 code.

 

Single coil pack often causes random misfire codes.

The usual test that is done is have the car running and unplug the coils one at time and see which one doesn’t cause a dip in engine power, thats the bad one.

 

p1259 code:

P1259 - Acura Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis (dtcdecode.com)

 

Not on my TL but on my Protege5, I had random misfires. Did the test above and narrowed it down to one coil pack (out of two). While the coils ohm'd out OK, there was a crack in the insulation near the spark plug on one of them. Since the caps were removable, I pulled them and could see the arcing down in the cavity. Closer inspection revealed the crack and associated arc trail.

So I'd pull the coils and carefully visually inspect them, pull the plugs and check them as well. You can swap the coil packs around but since you're getting multiple misfires, that may not help narrow things down.

 

I had this same problem recently and there were 2 problem coil packs. Even though they all tested good, the part where it’s insulated had cracked resulting in the misfire. and one had separated from the insulator completely, that was quite the mission removing it lol.

 

Well I re- checked the packs by pulling the connectors while it was running, on your guys advice. Cylinders 4,5, and 6 all caused a drop in rpm. Cylinder 1 on the other hand, did nothing when I pulled the connector. Looks like I've found at least one culprit.

 

Cool. If you wanna replace them all, I got NGK ones from rock auto for about $150. I also replaced my plugs while I was in there.