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

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.

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

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.

Did you check for codes?

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

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.

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.

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

http://www.autozone.com/autozone/catalog/parts/partsShelf.jsp?categoryDisplayName=Climate+Control&fromType=parts&fromString=search&parentId=52-0&currentPage=1&filterByKeyWord=ect+sensor&isSearchByPartNumber=false&navValue=15200113&categoryNValue=15299999&fromWhere=&itemId=113-0&displayName=Coolant+Temperature+Sensor&searchText=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.

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.

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.

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

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

Have you checked/replaced the ECT Sensor?

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?

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.

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?

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

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.

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?

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

Make sure she orders the ECT Sensor, not the ECT Gauge Sending Unit or the ECT Switch. With a bad Crankshaft Position Sensor, the engine may not start, may be hard to start, or it may die unexpectedly. Personally, I would first try replacing the spark plugs and skip the ECT Sensor for now.

Once you get it running okay, here are some recommended maintenance items:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563.html#post219991

I used the link you gave earlier for the ECT Part #SU 5584. We ordered it as a standby part. Plugs first, then O2 sensor, and ECT last. Both sensor and ECT sensor can be taken back. We just want to be prepared. Thank you for all your help. I will let you know as soon as I get it going what solved the problem.

Blessings.

My mechanic took the car to Autozone and said that a code came up show a MAP sensor. What I was told that the seal sometimes go bad and you get a vacuum loss. What do you think about that?

Replaced all the sensor parts, and still no joy. MAP sensor is showing on the diagnostics. Turning to that next.

Very possible. Did you replace the O-ring to the MAP Sensor? These sensors (transducers) are extremely reliable. Clean the connector--it's okay to spray this connector with WD-40.

Did you replace the spark plugs?

Changed plugs. Did all that was suggested. O-Ring on the MAP sensor was fine. Will suggest cleaning the connector. Trying to locate a MAP sensor. Will come in on Monday.

Ok, replaced the MAP, and no joy still! This is very frustrating. Mechanic says that there is a little foam in the oil. Water? Compression test was good @ 100 lbs per cylinder. He says that it seems like there is a potato stuck in the exhaust like it is not breathing. But no change when the manifold was cracked off. Idles good. But no power when revving it up. Any other suggestions?

Blessings

You may need a new mechanic. The compression looks way too low.

Compression Test. Crank engine over at least 7 compression strokes. In a healthy engine, compression should build quickly. Low compression on the first stroke, followed by gradually increasing pressure on subsequent strokes, indicates worn piston rings. Low compression readings on the first stroke, which doesn't build during successive compression strokes, indicates leaking valves or a blown head gasket (could also be a cracked head). If adjacent cylinders have equally low compression, there's a good chance the head gasket is the problem.

Cylinder Compression Pressure:

Standard: 184 psi
Minimum: 135 psi
Max. variation between cylinders: 28 psi

A leaking head gasket and water in the oil (foaming) go together. If tests confirm this, check the head for warping and the valves for damage. It could get expensive ($2,500).