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JMBSI · Sep 6, 2009, 11:25 AM

My 2002 Honda Civic is losing power when the engine is cold. When I am drive down the road and the engine gauge reaches 3000 RPMs it lose power. Once the engine has warmed up the problem goes away.

If I leave it in the driveway it and let it idling after 1 minute it wants to stall now this continues for 5 minutes and then the engine runs fine..

Any thoughts on this I have changed the spark plug and have placed a volt meter on the battery which read 14 volts while the engine is idling.

Any help would be appreciated.

JMBSI

TxGreaseMonkey · Sep 6, 2009, 11:49 AM

Replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. They become corroded, due to not changing the coolant frequently enough, flood the engine, and waste a tremendous amount of fuel.

JMBSI · Sep 6, 2009, 01:55 PM

I was told that it could be the secondary CO2 sensor.

JMBSI · Sep 6, 2009, 02:11 PM

Originally Posted by TxGreaseMonkey

Replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependant resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. They become corroded, due to not changing the coolant frequently enough, flood the engine, and waste a tremendous amount of fuel.

I was told that it could be the Secondary CO2 sensor or a relay in the timing what do you think.

TxGreaseMonkey · Sep 6, 2009, 02:33 PM

Did you check for codes?

JMBSI · Sep 6, 2009, 07:52 PM

Originally Posted by TxGreaseMonkey

Did you check for codes?

Yes the engine light did come on however the code said high voltage secondary C02 Sensor. But then I was told the CO2 sensor only operates when the exhaust heat up. I don't know what to think any more the more insight that is provided the less money that I invest in.

I appreciate your insight

TxGreaseMonkey · Sep 7, 2009, 06:57 AM

Setting a trouble code often means a sensor is reading out of range. It may read out of range because it is bad, or because some other problem is causing the engine to be out of balance (e.g. a bad ECT Sensor). A code dump alone may not pinpoint the problem.

What was the exact code? If it was P0138, I would:

. Check the wiring to the rear catalytic OXYGEN Sensor.

. Replace the ECT Sensor (cheap and easy).

. Replace the rear catalytic oxygen sensor, if the problem persists. This should be pretty straight-forward. Go with a Denso oxygen sensor--stay away from generics.

. Change coolant with a 50/50 mixture of G-05 antifreeze and distilled water.

The cause may be a bad ECT Sensor (caused by the coolant) and the effect a Code P0138. ECT Sensors become corroded by not changing the coolant frequently enough and by not using distilled water. Then, phosphate scale (insulator) develops on the ECT Sensor and causes problems.

JMBSI · Sep 7, 2009, 07:41 AM

Originally Posted by TxGreaseMonkey

Setting a trouble code often means a sensor is reading out of range. It may read out of range because it is bad, or because some other problem is causing the engine to be out of balance (e.g., a bad ECT Sensor). A code dump alone may not pinpoint the problem.

What was the exact code? If it was P0138, I would:

. Check the wiring to the rear catalytic OXYGEN Sensor.

. Replace the ECT Sensor (cheap and easy).

. Replace the rear catalytic oxygen sensor, if the problem persists. This should be pretty straight-forward. Go with a Denso oxygen sensor--stay away from generics.

. Change coolant with a 50/50 mixture of G-05 antifreeze and distilled water.

The cause may be a bad ECT Sensor and the effect a Code P0138. ECT Sensors become corroded by not changing the coolant frequently enough and by not using distilled water. Then, phosphate scale (insulator) develops on the ECT Sensor and causes problems.

Thank-you I will complete the repairs that were suggected. Once again thank-you.

TxGreaseMonkey · Sep 7, 2009, 07:56 AM

Here's what the ECT Sensor looks like and costs:

http://www.autozone.com/autozone/cat...ext=ect+sensor

The ECT Sensor has 2 wires going to it, while the ECT Switch has only 1. This should help you identify the proper component.

After you make the repairs, use a code reader to erase the code(s) and reset the ECM.

Spiritualquest · Oct 26, 2009, 01:04 PM

Will the sensor going bad always trip a code? We have 50 percent power after changing the catalytic and sensors (they really needed to be changed), but there is no code. Car works just fine, but just low power.

TxGreaseMonkey · Oct 26, 2009, 05:19 PM

No. I've seen many situations where sensors (and ECMs) were so bad that the car wouldn't run, yet a code was not thrown.

Spiritualquest · Oct 27, 2009, 01:26 PM

Could there be any other issue? The mechanic has brought the car up to temperature, but it still has less power. Taken off the sensor, and it looks fine. Any other suggestions? Fuel pressure is fine. Compression normal. Rear O2 sensor was bad from the parts store, and used the old one. They said it was not bad, but could it be bad still?

Just don't know where to go from here

TxGreaseMonkey · Oct 27, 2009, 02:04 PM

Are you using the exact NGK spark plugs that came in the car?

Have you checked/replaced the ECT Sensor?

Spiritualquest · Oct 27, 2009, 02:19 PM

Yes, it still has the original plugs. Plugs were tested good. No, I have not replaced the sensor. Sensor was taken out and it was not corroded. Could it still be bad even if it is not corroded or shows signs of being bad?

TxGreaseMonkey · Oct 27, 2009, 02:21 PM

Is your car a 2002 Civic? What engine and how many miles are on the car?

Your problem may just be that you need to install a new set of NGK spark plugs.

Spiritualquest · Oct 27, 2009, 02:38 PM

Yes, 2002 Honda EX. 4 cyl. 2.7, I believe. Mechanic says the plugs are fine, but he admits that he does not know anything about Hondas. Could the back flow of exhaust foul a plug?

Are they expensive to replace?

Spiritualquest · Oct 27, 2009, 02:40 PM

Sorry, approaching 200K miles. Good reliable civic up to now.

TxGreaseMonkey · Oct 27, 2009, 04:36 PM

I believe replacing the spark plugs, with the same NGK plugs that came in the car, could solve your problem. Even platinum plugs should be replaced at about half the recommended mileage.

Most performance-related problems on your generation of Civic will be related to spark plugs, coils, and crankshaft position sensor.

Spiritualquest · Oct 27, 2009, 05:07 PM

Thank you. I told my wife to order an ECT sensor, new plugs, and a new O2 back sensor. We are changing mechanics. Seems like he wants me to do his work for him. I am going to find someone that has some mechanical sense without the computer. Why is it that mechanics that don't have a computer can't figure out what is going on with a car? Oh well. Car has never had a tuneup since 13K miles, and so it is really due. Anything else you can think of that I might do to it?

Spiritualquest · Oct 27, 2009, 05:15 PM

What would be the symptoms if the crankshaft position sensor went bad?