It seems from going over all the relevant threads, that a significant number of people running JDM engines in the US experience a bad hesitation/stumbling/misfiring/low power problem at lower RPMs (1000-4000rpms).

People have gone crazy going through great efforts to solve this problem with little sucess, including replacing or cleaning components in all the following categories:

IGNITION
spark plugs, wires, distributor, distributor cap & rotor

AIR
PCV valve, EGR valve, EGR intake ports, throttle body

FUEL
fuel filter, fuel pressure regulator, fuel injectors

SENSORS
knock sensor, MAP sensor, TPS sensor


Whenever someone seems to solve the hesitation problems, it is temporary or an inconsistent fix. Not all cars with the hesitation are probably having the same problem, yet the high frequency of JDM engines with hesitation suggests there is a common thread.


The one thing that JDM engines do all have in common is higher compression, and that the engines and their ECUs were designed to run the higher octane fuel available in Japan.

I'm beginning to agree that this is the most likely explanation. I think the root cause of the hesitation is the knock sensor sensing knock due to the lower octane fuels available in the US detonated in the higher compression engines. My hesitation problem is especially bad, and I am running an S Spec H22 with 11.0 compression.


So if anyone has more info on this, let's make this thread useful.

- If you've done a swap, state what kind: regular JDM, Type S, S spec, OBD1, OBD2, etc.
- If you are having the hesitation problem, say so and describe it.
- Any new definitive fixes, theories, etc. For example, if you are using octane booster has it consistently solved the problem? If you are running a P28 or P72 with P13 knock board and a Hondata, has that solved your problem? Has getting your fuel injectors balanced been a long-term solution?

 

i have done a swap but the only thing is that the rev limiter kicks in at 2500 it just shuts the engine off

 

hrmmm.. well I think your right.. I beleive in japan the min octane that they use is 93.. since we only have 91 you would think that knocking may occur. after doing a jdm gsr swap into my ek I noticed that when you press down on the throttle that it isnt as consistant as you think. sometimes it would take a while for the car to go and sometimes on the better days theres no hesitation. I have a bone stock jdm gsr with a jdm p72 ecu obd2. maybe we can bypass the knocksensor with hondata? but is the knock sensor really causing the lagg?

 

I've heard ppl adding toluene to their gas to up the octane, why not try that and see if the hesitation abates?

 

bump this thread! I have the same problem it is driving me crazy. Here in Canada we have a gas station that carries 94 octane. It's the only fuel I use and this problem still happens. Somedays the car is sluggish, some days it feels like it "wakes up". Its a strange thing. Someone must know the answer.

 

ttt