Hi.

When the A/C is on and wait on the stop sign or red signal, the rpm go up and down between around 450 and 550 rpm. I feel the vibrations by my hands on steering wheel. As soon as the rpm goes up, the vibration is disappeared and car is just fine. What is the problem?

Thanks.

 

idle sounds a bit low. should be closer to 750 rpm

 

Your car's idle needs to be adjusted. It's rumbling at low speeds because it's hesitating to want to shut off.

Whenever the A/C is on it will always lower your idle a little because some of the power is being used for the A/C motor. Even with the A/C on though, it should not be as low as you are describing.

You need to take it to a shop to get the idle speed adjusted

 

Whats idle at without the ac on?

Dont touch the idle adjustment screw, especially if it still has the factory paint seal over it.

Im wondering if its the IACV.

 

We need to know what your idle is when the A/C is turned off

 

Around 600 rpm at the "N" and 500 rpm at "D".
Also I just found out the rattle noise when the gear shift from "N" to "D".

 

Your idle is quite low. It should be ~750 with no accessories on.

 

Finally I got the codes p0170 and p0172 in this afternoon.
What did I wrong with the valve adjustment?

 

Fuel trim malfunction and system too rich on bank 1.

 

P0170: Fuel trim malfuction (bank 1)
P0172: System too rich (bank 1)

Can anyone help me figure this out?

 

Replace your IAC valve.

 

I found out an unpluged vacuum hose. After the hose put back to engine, the CEL is gone. However the CEL comes up again and blinks when the rpm goes over 4000. Also the engine loses the power.

 

What if the crank pulley was turned without removing spark plugs? I think the timing belt is off while I am turning the crank pulley.

 

03 CL Sport, 158k
Erratic idle from 500rpm - 2k rpm
Engine light goes on and off
Removed throttle body and then IAC.
Iac was crudded up and would only rotate 90deg instead of 360deg.
Drilled out two 5pt bolts (did not have socket) and removed solenoid. Valve was sticking from crud. Cleaned with carb cleaner. Now retates freely 360 deg.
Replaces solenoid (watch which way vane installs) and used new allen bolts.
Installed IAC to throttle body and body to engine. Fired right up and idles perfect at 1k.
Saved $160 for new IAC on EBAY and $260 for new one at Acura.
Easy job took about an hour.

 

Here is what happen end up with my stupid valve adjustment DIY.
When the front crank pulley was turn, I forgot to remove the spark plugs. I force to turn the pulley and then adjust the valves at each turns. It turn out that the engine didn't even start at the last night.

My car is in the shop now. A mechanic shows me all the front valves (exhaust and intake) are bent because the valve too tight. I don't know what I did wrong. I followed the manual exactly except for removing the spark plugs. The engine needs all new front valves and readjusts them too. It costs me $1500.

Thanks,

 

Sorry to hear. I know what it's like to have bent valves; however, mine was due to the crappy tensioner Acura used initially back in the day when the car was newer.

 

I brought my car from the shop today. It cost me $1342.

*Problems & Fixed: All six intake valves bent in the left cylinder head. Removed left cylinder head to have cylinder head mechined. Had all six intake valves replaced with valve stem seals.

- Intake valves: $82.20
- Head bolts: $64.56
- Head set: $186.33
- Coolant: $15.50
- Work requested (Machine shop): $325

If anyone plan to adjust the valves, please reconsider it seriously.

Thanks.