Honestly this is the type of problem that is almost entirely impossible to
diagnose online. There are many things that could be the cause of this and
without seeing the car anything I tell you would simply be a guess and then
you would continue to replace parts you don't need. That adds up fast.
My concern is that the Honda dealer can't or won't identify the cause. When you say that do you mean they don't know what the problem is or they can't duplicate it?
My best advice is to forget the dealer and go to a good shop that has ASE certified techs. You'll find independent shops tend to be more willing to work with you to diagnose and repair your car.
I am currently having problem with my Honda Civic 1.6 EFi Automatic. My car jerks (like when you are driving a manual car and you don't release the clutch properly when changing gear) whenever I am driving at the range of 35 - 45km/h. If I were to shift to D3 or accelarate, then the jerk will go away.
Changed the Fuel filter, Spark plug, tested on the Rotor head, coil, spark plug cable and none of these seems to be the root cause. Sent my car to the Honda service center and they also could not identify the root cause.
Could it be the gearbox?
Desparately need advise! :(
Actually, the Honda mechanics could simulate the problem but they just can't tell me the cause. I don't know if the following could help you understand my car's problem better:
When the engine is cooler (when I start driving) it doesn't jerk and only when the engine got warm up (5-10 minutes later), then the jerking will be obvious. Also, when it jerks, if I accelarate, or shift to D3, then the jerking would stop.
Anyway, I'll be sending my car to one of the outside mechanics that uses diagnostics program that could help to identify problems.
Please, by all means inform me should you have any clue. Thanks!
Way outside guess here but let's see how close I am. It sounds like it
might be the torque converter locking and unlocking. I base that theory
1. When you accelerate or downshift the PCM automatically commands the TC to unlock.
2. The PCM won't let the TC lock until the trans fluid reaches a certain temperature (not sure what that is on your car, probably around 150F).
3. In D4 at that speed range the engine is running at a lower RPM so it would be more noticable than a higher speed.
Now the question is what the root cause is, and that could be several things. Let me know what fixes it and how close, or far off I was.