2008 Honda Fit

Engine Performance problem
2008 Honda Fit 4 cyl Front Wheel Drive Automatic 26000 miles

This happen suddenly when I do few thing

1) install back my catalytic Converter and sensor.

2) Install Extra piggyback

Now when my car stop at traffic light with gear at D mode, the car virbration and RPM drop to 600.

Tuner try to tune up also same problem.

Noisely from under car, I told them that maybe exhaust leak, but they can't find. What happen.
September 6, 2009.

Hi clanbuster,

Is the MIL indicating?
Did you try to retrieve for trouble codes?

Sep 6, 2009.
Sorry, what I MIL?

There is no engine check light.
I only had super high vibration when come to stop with gear at D mode. RPM too low

Sep 6, 2009.
MIL = Malfunction indicator light = Check engine light.

Does vibration goes away if you increase the idling speed?
What is the idling speed when gears are engaged and when in neutral?

Try the PCM relearn procedure to see if it helps.

The idle learn procedure must be done so the ECM/PCM can learn the engine idle characteristics.
Do the idle learn procedure whenever you do any of these actions: • Replace the ECM/PCM.
• Reset the ECM/PCM.
• Update the ECM/PCM.
• Replace or clean the throttle body.
• When the engine or transmission is disassembled.

1. Make sure all electrical items (A/C, audio, lights, etc.) Are off.
2. Reset the ECM/PCM with the HDS.
3. Turn the ignition switch ON (II), and wait 2 seconds.
4. Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, or until the engine coolant temperature reaches 194 °F (90 °C).
5. Let the engine idle for about 5 minutes with the throttle fully closed.

NOTE: If the radiator fan comes on, do not include its running time in the 5 minutes.

6. Verify on the HDS data list that the idle learn procedure is complete.

If you do not have the HDS, a scanner would do to check and erase DTC if any.

Sep 7, 2009.
What is HDS, where to purchase?

Anyway, I did nothing and the idling speed is ok now.

Now the problem is when can reach 2500 RPM, there is loud " toh toh toh" sound from engine, the car jerk jerk, but when car reduce 2400 RPM, nothing happen.

So my let my ECU re-learn, should I keep with this speed at 2500 RPM until stable?

Sep 8, 2009.
HDS is Honda Diagnostic System which is too pricey for DIY.

Keep rpm at 3,000 until radiator fan comes on, then release throttle and let it idle for 5 minutes, excluding time when radiator is running.

Don't drive the vehicle, relearn is done with engine stationary.

Sep 8, 2009.