HarryD

Hey guys,

I'd like to think that I am mechanically adept, but this one is *really* bothering me, I have zero ideas here.

Here's a video of the symptoms:
http://youtu.be/0UvraTFpOuE

My car is suffering from shakes at idle, puffing sound out of exhaust:

• 2002 AP1 w/ 98k miles (owned since ~50k)
• NO CEL
• AC off
• Not touching the clutch (in neutral)
• Radio/everything else off
• Compression checked 10k miles ago, 220 psi across the board
• Valves adjusted 40k miles ago
• New OEM spark plugs, proper plugs, proper torque
• New OEM engine mounts + tranny mounts
• New OEM fluids all around
• IAC cleaned 10k miles ago

The first time it happened, I thought it was a little earthquake (being in California), but now it happens randomly every 5-20 seconds. Like if someone is pushing the car, a quick shake, not constant shaking, just a quick jerk. And then lots of smooth idle. And then randomly repeat.

Most of the time the idle does not blip or move when this happens (sometimes it does 1 bar)... More pronounced at [AP1] 1 bar cold, but also happens at 3 bars fully warmed up.

Aside from this, the car feels strong. I redline multiple times a day, every day (after fully-warming up).

But what the heck... Any ideas?? What should I check, where do I even start??

windhund116

Air cleaner filter?

Reckon

Perhaps the engine mounts are reaching their lifespan? And while not directly related, has the MAP whack been done?

windhund116

Check for vacuum leaks, too.

HarryD

• Air filter was replaced <5k miles ago
• Idle is fine, map was whacked <20k miles ago, was never an issue.
• I replaced all the engine + tranny mounts myself <5k miles ago, new Honda OEM--surely they didn't break in a few months?

I did have a vacuum leak once when I was cleaning my IAC and one of the vacuum lines came loose, but that gave me a CEL and I immediately plugged it back in.

Any other ideas?

HarryD

I stopped in an s2000 shop and while they refused to sit in my car for 1 minute to "feel" the shudder/shake, they said try a valve adjustment or fuel injectors??

Reckon

You did the VA last about 40k miles ago...not sure that would really cause the shaking/shuddering. Fuel injectors aren't a known issue for the S2K either.

What about your fuel pump?

HarryD

How do I check a fuel pump? It's getting worse every day, and now it's happening while driving, too. Still random, still 100x worse on a cold start.

It feels like a ticking time bomb and I hate this feeling. It's not normal.

Could it be rod knock, even though there's no sound change?

Billman, any ideas?

HarryD

Possibly related, or unrelated, but I had a 5-6 year old battery die on me a few weeks ago. This shaking started after that, but has been getting worse daily.

Can an alternator or bad battery connection cause the engine to shake so violently so randomly?

Car Analogy

It shouldn't. If the alternator randomly cuts out completely for a few seconds, the battery can easily run the ignition. Likewise, if battery were to go totally dead somehow for a few secs, the alternator can easily run ignition. So neither by itself should be able to cause this issue.

The rapid onset, and just as quick resolution of the symptoms makes me think misfire. But you'd expect it to throw a misfire code.

You've removed the coil packs several times (new plugs, VA, etc). Maybe the coil pack electrical connectors are damaged, and intermittently losing electrical contact. They are known to get brittle and break. You can buy just the plastic connector and swap it onto your coil pack harness. Search on this form for vendor of these.

But again, I wonder why you wouldn't get a misfire code.