Engine Rough Idle Problem- Really Need Help

[Quebecker]

Hi,

I'll start with info on my car.

Honda Civic 2004 EX, 1.7L, 4dr, Auto Transmission
160,000KM

Recent work done:

- I changed the plugs
- I changed air filter
- I cleaned the IAC Valve
- I cleaned the throttle body
- I cleaned the EGR Valve
- Ran injector cleaner through it one time
- Changed the AFR sensor and O2 Sensor
- Changed Timing Belt (125 000 km)
- Reseted ECU and processed to a Idle Learn procedure

- Removed all the HHO parts (reactor, EFIE, ....)


I have a real problem with my car. :confused: When the engine is hot (after warmup enrichment phase), the idle is rough when I come to a complete stop, whether I'm parked or stopped at a light. I can definitely feel it vibrating. The engine shake (almost ready to stall) and I can see my exhaust pipe is vibrating quite a bit (more than normal). This is less perseptible on the "P"ark position and amplified one the "D"rive position

I can't feel it when I'm driving. It's OK when the car is cold (durint warmup enrichment step).

When this happens, I noticed that the Short Fuel trim go down to about -15 to -20%. NO CHECK ENGINE LIGHT. The RPM is about 650-750.

Weird: When this happends, If I rev the engine to 3500 to 4000 rpm then the STFT value return to a more normal reading to about +5% to +7% and after that, the engine is OK. the rough idle stop until next time.

When I slowed down, the ECU is in open loop and no problem but when the car is to stop/red light he returned to close Loop and the vibration happend.

To make a test, I purposely disconnect a sensor (AFR sensor) so that the CEL comes on and the computer is in OPEN LOOP. During these two weeks of testing, the rough idle problem never happend.


Other than that, there are no other noticeable problems. The car has lots of power, and gas mileage is normal.

If you can help me, it will be very very appreciate ;)


DATA - TEST #1 (11h53)
http://img163.imageshack.us/img163/5856/data20130226115323.png

DATA - TEST #2 (12h47)
http://img266.imageshack.us/img266/5976/data20130226124700.png

[myoldyourgold]

Are you are sure it is a engine problem. Check the motor mounts especially the one on the transmission. When that one goes the engine shakes like crazy. When you come to a stop and you put it in neutral does it smooth out?

[koya1893]

Hi,

I'll start with info on my car.

Honda Civic 2004 EX, 1.7L, 4dr, Auto Transmission
160,000KM

Recent work done:

- I changed the plugs
- I changed air filter
- I cleaned the IAC Valve
- I cleaned the throttle body
- I cleaned the EGR Valve
- Ran injector cleaner through it one time
- Changed the AFR sensor and O2 Sensor
- Changed Timing Belt (125 000 km)
- Reseted ECU and processed to a Idle Learn procedure

- Removed all the HHO parts (reactor, EFIE, ....)


I have a real problem with my car. :confused: When the engine is hot (after warmup enrichment phase), the idle is rough when I come to a complete stop, whether I'm parked or stopped at a light. I can definitely feel it vibrating. The engine shake (almost ready to stall) and I can see my exhaust pipe is vibrating quite a bit (more than normal). This is less perseptible on the "P"ark position and amplified one the "D"rive position

I can't feel it when I'm driving. It's OK when the car is cold (durint warmup enrichment step).

When this happens, I noticed that the Short Fuel trim go down to about -15 to -20%. NO CHECK ENGINE LIGHT. The RPM is about 650-750.

Weird: When this happends, If I rev the engine to 3500 to 4000 rpm then the STFT value return to a more normal reading to about +5% to +7% and after that, the engine is OK. the rough idle stop until next time.

When I slowed down, the ECU is in open loop and no problem but when the car is to stop/red light he returned to close Loop and the vibration happend.

To make a test, I purposely disconnect a sensor (AFR sensor) so that the CEL comes on and the computer is in OPEN LOOP. During these two weeks of testing, the rough idle problem never happend.


Other than that, there are no other noticeable problems. The car has lots of power, and gas mileage is normal.

If you can help me, it will be very very appreciate ;)


DATA - TEST #1 (11h53)
http://img163.imageshack.us/img163/5856/data20130226115323.png

DATA - TEST #2 (12h47)
http://img266.imageshack.us/img266/5976/data20130226124700.png

From your original post I did not see you mentioning about the plug wires or cap and rotor, unless this model has the COP system. It sounds like the same situation on an accord I was working on last week, it was the cap and rotor. They had a lot thermal corrosion on the rotor tip and the cap terminals.

[Quebecker]

From your original post I did not see you mentioning about the plug wires or cap and rotor, unless this model has the COP system. It sounds like the same situation on an accord I was working on last week, it was the cap and rotor. They had a lot thermal corrosion on the rotor tip and the cap terminals.

Hi Ben,

it's a ignition coil cop

[Quebecker]

Are you are sure it is a engine problem. Check the motor mounts especially the one on the transmission. When that one goes the engine shakes like crazy. When you come to a stop and you put it in neutral does it smooth out?

Hi Carter,

Yes, when I come to a stop or red light and I put in neutral, it smouth out.
Still present but much less noticeable

But, if it's that, why it stop when I rev the engine to 3000-4000 for a couple a secondes ? Very weird

Also, I'd be surprised if it is a broken motor mounts because when the problem happens and I stop the car, the next start is very difficult.

Thanks

[myoldyourgold]

This tells me it is the motor mount and most likely the one on the trans. When you rev it up the torque locks the engine in one position and it does not vibrate. I would check all the mounts but the bigger ones usually do not give trouble. You might have some other problem. Have you checked the compression in each cylinder?

[Quebecker]

This tells me it is the motor mount and most likely the one on the trans. When you rev it up the torque locks the engine in one position and it does not vibrate. I would check all the mounts but the bigger ones usually do not give trouble. You might have some other problem. Have you checked the compression in each cylinder?

Here is the next steps !!!

- checking compression
- ajusting the valves
- cleaning pvc valve

Regards

[koya1893]

Here's something you might want to consider, I recently did some work on a Lincoln LS (replacing complete timing chain and tensioners) which has the Jaguar engine 3.9 DOC. It ran rough during idle (low rpm) but when the rpm increased it ran perfect, now those engine we're known for their timing chain tensioner going bad and the sign for that is rough idle and thicking noise. so you might want to look at your valve timing system, I believed you have a timing belt on that motor. I could be wrong.

[Quebecker]

Here's something you might want to consider, I recently did some work on a Lincoln LS (replacing complete timing chain and tensioners) which has the Jaguar engine 3.9 DOC. It ran rough during idle (low rpm) but when the rpm increased it ran perfect, now those engine we're known for their timing chain tensioner going bad and the sign for that is rough idle and thicking noise. so you might want to look at your valve timing system, I believed you have a timing belt on that motor. I could be wrong.

You're right !!!!
This car have a timing belt
I changed the timing belt Ã* 130 000km

[koya1893]

You could try focusing on a vacuum leak, take a can of carb cleaner and spray all vacuum line attached to the intake. I am sure you know the reaction when the spray reach a leake.

[motocross1550]

if the fuel trims go negative it means its running rich, not as many things cause it to run rich as lean. my car had a similar problem and i flushed the injectors and it fixed it. also worked on a truck that idled rough and a flush only fixed it for a few days. pull the fuel rail and cycle the key from off to run a couple of times. don't crank it over and see if any fuel is spraying out of any of the injectors. none should come out