Twilight

Hello,

2004 Honda Civic EP3 Type-R with K20A2- engine. 128.000ml.

I'm having hesitation problems with my car. The hesitation itself is very mild but noticeable.. The problem occurs when opening the throttle, it is best felt after changing gear and it hesitates right after you've opened throttle. It sputters for a few hundreds of a second and it is clearly heard trough the exhaust like its running at wrong A/F- ratio. (1) When the engine is cold, there is no hestiation at all. (2) When the cold- idle cycle is going to end, hesitation does occur. (3) When driving above 5500rpm, there is no hesitation. (4) It happens every time the engine is running at normal operating temperatures. (5) WOT does not eliminate the hesitation. (6) It returns normal MPG, at 30mpg in my driving conditions.

I've limited the source into eight different possibilities;

1. Throttle position sensor (TPS) fault
2. Intake air control valve (IACV) fault
3. Exhaust gas recirculation (EGR) related fault
4. Lambda- sensor fault
5. Ignition fault
6. Manifold absolute pressure (MAP) sensor fault
7. VTC oil control valve
8. Fuel filter

1. I've heard TPS- sensors go wrong, but I have doubts since it works fine when the engine is cold. I'll have to plug it in into Honda Diagnostics system and measure the throttle position sensor.
2. This seems most likely, the car is been running for nearly 130.000 miles so carbon deposits and other dirt may cause some problems. The engine does not hesitate when the engine is cold (I assume IACV is open) but starts to hesitate when the engine is starting to warm up (I assume IACV is closing).
3. Exhaust gas recirculation valve might be stuck open for a bit, but it seems unlikely since the car works well when cold.
4. Lambda- sensor could also be the cause, but feels unlikely because the hesitation only occurs during opening of the throttle but the engine works well after that.
5. It could be ignition related, plugs or coils, but seems unlikely since it works well during start- up, cold, hot and under loads.
6. MAP sensor, seems unlikely since it returns normal MPG and engine works well in other loads.
7. VTC oil control valve, I'm actually not that aware of the problem, but it seems that some symptoms could relate to that.
8. Fuel filter, there is a filter inside the fuel pump assembly. I might need to replace it, I don't know whether has it been changed or not.

Please let me know if you would have some ideas how to fix the annoying problem. I don't want to be spending unnecessary time under a Honda bonnet so I thought I ask from you here.

Thank you,

I might add an video from the fault if it helps.

-Ville

spd8r

Check your fuel pressure. When's the last Time you did a fuel filter.