Shaking at idle - coils or mount?

[Shua586]

I've searched the forums on shaking at idle and it seems like the consensus is either bad coils/plugs or a faulty motor mount.

Background: Car (2004 6S) was running fine yesterday. It's been raining a bit here in Tacoma, especially in the past couple days. I park my car under a cover. Today I drove about 5 minutes and parked uncovered in the rain for 45. When I started it again, the car was shaking very noticeably. I checked under the hood - the motor was shaking but I do not know if it was more than usual - it also seemed a bit quieter, though I cannot say that definitively. It also pulled a CEL. I shut it off, let it rest for a minute and turned it back on. It was still shaking, but less so than before - CEL still flashing.

I then drove back to my apartment (5 minutes), shaking continued to be noticeable at idle. The CEL varied between flashing and solid. At home, I did a reset (disconnect battery, drain, etc). The CEL went away but I still noticed some shaking at idle, though not as intense at first. I preemptively drove it to Auto Zone in case I needed the CEL read if it popped back up. In the 5 minute drive, the CEL did not come back on. I shut off the car in the parking lot, let it rest for a minute, and turned it back on. No change. At this point, I tested revving the engine - the shaking becomes more noticeable between 1 and 1.5 RPMs then returns to the previous intensity.

I drove down the street, parked the car at the coffee shop I now write this from and have not started it up again. It's been a couple hours and I will be driving again soon so I will edit the post if I get any new results.

EDIT: When I went to leave the coffee shop, I started my car and it was shaking as bad as originally. I shut it off and we took a friend's car. I just picked up my car and drove it back to the apartment. Same shake as before. When I got back, I did a little testing. First off, after it warms up, the shaking reduces significantly (giving evidence that it may be a misfire/plug/coil problem as indicated in The Great NY's post in a previous thread). Secondly, if I rev slowly, it hiccups at 1,000 RPMs. If I hold it there, the shaking is worse than at idle - when at standard operating temperature, I have not tested this when cold.

Any thoughts? Coils? Plugs? Mount? Gremlins?

Thanks,
Shua

[Shua586]

=/ Anyone?

[MY_LO_MAZDA6]

so you didn't get the CEL checked out? i would do that asap.

i would say it isn't the mount, cuz that wouldn't give you a CEL. i would guess for a bad coil. how many miles are on the car? cuz stock coils have been known to fail, especially on a high mileage engine.

fyi...i have 6 good stock coils for sale if you need one, or the whole set.

[Shua586]

QUOTE (MY_LO_MAZDA6 @ Oct 18 2009, 04:42 PM)

so you didn't get the CEL checked out? i would do that asap.[/b]

It ended up flashing a CEL again the next day. It only happens when I am in gear and have my foot to the gas. I checked it at Auto Zone and it appears to be a misfire in cylinder 3 (P303). It's gotta be the coil, plug, or wires. My guess is the coil. BTW, they are all Sniper coils. I already had to replace 1 a few months ago. When I get back from my trip to San Antonio, I'll switch the Sniper for the stock coil and see if the problem persists. Of course, it's one that requires the removal of the IM. Woo!

-Shua

[MY_LO_MAZDA6]

o wow, that sucks. did you get a bad batch or what? one thing you could do is to make sure it didn't randomly come "unsnapped". like press down on it to make sure its in there good.

sorry to hear its one in the back. just do the EGR Mod and removing the IM is MUCH, MUCH easier.

[karlt10]

In my Integra it was a shot motor mount.

What does your throttle body look like? Does it look like you could grow tomatoes in it?

There's not many, but could be as simple as a vacuum leak/line.

[The Great NY]

shaking at idle and a misfire code. leads me to think its the coil on that cylinder. if you want to be sure, put the coil on cylinder 3 on cylinder 1 or 6 or any other cylinder and see if the code changes cylinder position.

if it doesnt. get some plugs