Honda Civic, Acceleration Problem

JUST AS A GUESS. It sounds to me like your computer detects something bad wrong and is putting the car into LIMP mode. This shuts down everything which is not essential so you can get the car into a shop. If you can find someone with a CODE READER, they can connect to the computer and find out where the problem is. Without the codes, it would be dang near impossible to troubleshoot. The problem could be anywhere. If you could get us the codes, we could possibly help you. There are people here much better at this than myself.

Merry Christmas

Bill

The 2003 Honda Civic DOES NOT have a limp home mode.

Thank you! That is why it was just a guess.

Bill

I had a similar problem on an old Fiesta 1978 where the converter started coming apart and at times would plug the exhaust. It was intermittent and symptoms were loss of power and rpm. This car had no computer but when I shook the exhaust pipe you could hear something rattling. If the codes do not show a specific sensor causing it take a rubber hammer and tap the converter to see if you get a rattling sound.

Hello.I agree with a previous post that the Catalytic Converter is blocking the exhaust.Seeing if it rattles by bumping it is a good test however if it does not rattle it still can be the problem from overheating/melting.When you are having the problem look underneath and see if the Cat is glowing red.Sure way to verify is to open the exhaust before the Cat and see if problem goes away.Like to hear how you are making out.

There is somewhere in one of the service manuals for that car a spec for pressure drop across the Cat Conv. I once watched a tech drill a small hole at the inlet and outlet of the Cat Conv and install a pair of pressure gauges. He then ran the engine at various speeds while watching the gauges to determine if there was a blockage. He finished by plugging the holes with stainless screws.

You can check for a restricted exhaust system without drilling holes. Connect a vaccum gauge to intake manifold vaccum and the gauge should start out around 25 in of vac. and steadly drop off as engine rpm is increased to around 2k-2.5k.

Let's do this : Your vehicle has a ECM and EFI . Computer module and Electronic Fuel Inject. 2003 - Lack of acceleration , probably accompanied by overheat (chk eng ).

To remedy : 1 - replace NGK stock plugs with anything else , and throw them away . AC Delco , Champion , most domestic suppliers will list this vehicle .

Go Bosch if you want performance .

2 - Try it again.

You have dirt in fuel tank that prevents proper fuel supply through partially blocked fuel filter in fuel line or in carburetor. Just clean tank from sand or other dirt plaguing your fuel system.

Also it is possible that the back flow valve is so dirty that does not opens properly.

Another alternative is that the carburetor is not properly tuned.

This is not an all-inclusive list, and it is possible under some circumstances to add or delete items. It is a basic performance testing menu.

Basic testing sequence:

Pre (cold) start attempt:

Check for proper battery voltage

Install fuel pressure gauge

Check for pressure and volume (check spec table in repair manual)

Install engine analyzer

Check for spark at a minimum of two cylinders

Check for injector pulse at a minimum of two cylinders

Pull codes

Check ECM/ECU data stream

Attempt to start: if starts and runs:

During running, recheck:

Fuel pressure/volume

Primary/secondary ignition scope traces

Injector operation (on scope)

ECM data stream

If potential problems are not uncovered during this inspection, reply with your results to allow further consideration of your problem and potential avenues to investigate.

Hello,back to the problem."the rpm does not go beyond 3000 and (noise comes out of the exhaust like its leaking)".This last part confirms you have a blockage in your exhaust system,most likely the catalytic converter although a collapsed muffler or crushed tailpipe will also cause similar effect.If you open the exhaust before the cat and test drive there should be a noticeable improvement indicating that the exhaust is restricted in the cat or afterward."When the problem starts, the check engine alarm comes up".The next question is why is it restricting the flow of exhaust.If the Cat rattles as posted above the honeycomb looking stucture inside the cat has broken and turns sideways restricting the flow.If you are seeing black smoke from the exhaust it is an indication the fuel air mix is too rich and can black soot block the flow.Get someone to pull the codes from the ECM.Pay particular attention to codes relating to too much fuel,02 Sensors,coolant temperature sensor,etc.Check the wiring to these sensors as a wiring problem can feed the ECM a continuous lean signal resulting in too much fuel.Also should pay attention to codes relating to the variable valve timing and variable valve timing control solenoid which can cause the ECM to not permit the use of high lift camlobe operation via oil pressure through the solenoid which would normally occur above 3000 rpm which some mechanics call limp in mode.If i remember correctly your honda dealer has technical service bulletins relating to both 02 sensor and VTEC.You should also know that low oil pressure can also cause similar effects.If the ECM does not see an immediate increase in oil pressure following the VTEC Solenoid opening it will set a code and limit fuel delivery which some mechanics call again a limp in mode.OK it's nap time.Like to hear how you are making out.

bad 02 or temp sensor go's bad and makes the car run rich and clogs the cat.the rattle is the broken ceramic in the converter. this made my wifes 60,000 mile Honda crx burn beyond repair

If the check engine light comes on, you must read the codes generated. My guess is that one of the VTEC codes will show up. If the sensor or solenoid is malfunctioning, or if the filter screen is clogged, you get symptoms like you described. Even a very long time between oil changes can effect the VTEC system.

There are many threads on the web, such as this one, dealing with VTEC issues.

Without reading the codes, there is little point in trying to fix the problem. What made you want to change the exhaust manifold?

not all malfunctions will cause the check engine light to come on but will show up on the diagnostic equipment.

True, although in this case, the OP said the the check engine light came on, so there is certainly a code generated... and it is pointless to start replacing things like exhaust manifolds without first knowing what the codes are.

Exactly

Some years ago, before a fix was devised, Piper aircraft (PA28-140) had a problem that would cause the engine to loose power in flight. The baffles in the muffler would work loose (rust) and fall down on the exhaust port and limit the flow of the exhaust. This sounds a lot like the problem you describe, be it the Cat or the muffler.