I have a 2004 honda accord. It has 200k+ miles. I noticed a difference in the idle back in summer when i turned my ac on but it wasn't too bad, over the last couple months its gotten worse and now is vibrating really hard when i put it in gear and i am stoppped. If i put in N or P it stops for the most part. But if i have it in gear and turn ac or heat on, it ridiculously shakes. My rpms do not move. I have an aftermarket cold air intake on the car so the only code its throwing is for the MAP sensor because i don't have one. Is that my problem? Should i take the aftermarket off or is it something completly different?

 

You should have a map sensor in the vehicle, because that is how the PCM knows the amount of air entering the engine. Having a map sensor will help the engine, but it doesn't sound like your problem.

In my opinion, a cold air intake doesn't gain you significant power and can easily cause water to pulled into the engine. A stock setup is my preference.

Since you are having issues with shaking when putting the car into gear, I'd look at the motor mount. The front mount is vacuum controlled, so there could be a torn motor mount or a vacuum leak going to the motor mount. I believe only the front motor mount is vacuum controlled, but the rear mount might be. A vacuum issue is also likely, because your symptoms are happening at idle.

 

MAP sensor is on the intake manifold, not on the aircleaner pipe. So having a CAI doesn't take away the MAP sensor. Check the code number again (what's the actual number?) & check the wiring plug for the MAP sensor.

It looks like only the front engine mount is vacuum-operated, and that's only with automatic transmissions (V6 and 4cyl both). So that vacuum-controlled mount seems like the most likely problem.

Since the RPM holds steady, that means your IACV is working. Just to rule it out, check whether shaking is caused by anything funny with the external drive belt. Have someone hold the brake & shift it into gear. Turn on the AC & watch the drive belt. Does it look like any of the pulleys begin wobbling under the load of the AC?

 

Might also be this:
Engine - Vibration In Idle

04-024

May 6, 2010

Applies To:
2003 Accord L4 A/T-ALL
2004 Accord L4 A/T 2-door-From VIN 1HGCM7...4A000001 thru 1HGCM7...4A009608
2004 Accord L4 A/T 4-door-From VIN 1HGCM5...4A000001 thru 1HGCM5...4A057899
- From VIN 3HGCM5...4G700001 thru 3HGCM5...4G703063
- From VIN JHMCM5...4C000001 thru JHMCM5...4C028489

Engine Vibrates While Idling In Gear

(Supersedes 04-024, dated May 4, 2004, to revise the information marked by the asterisks)

*REVISION SUMMARY

Under PARTS INFORMATION, the engine idle smoothing kit was replaced with individual parts.*

SYMPTOM

Excessive vibration is felt in the seat and steering wheel when the transmission is put in Drive or Reverse. The vibration may be worse in cold weather or with loads, such as with the A/C on or when the steering wheel is turned.

PROBABLE CAUSE

Not enough engine damping.

CORRECTIVE ACTION

Based on the VIN, do either REPAIR PROCEDURE A or REPAIR PROCEDURE B.

REPAIR PROCEDURE A:

Replace the front engine mount. Loosen and then torque all engine mounting bolts.

REPAIR PROCEDURE B:

Replace the front engine mount, loosen and then torque all engine mounting bolts, and install a heavier front bumper weight.