Hi, I'm new here and this is my first post. Anyway I had a few question, I did search, but really couldn't find anything. Ok 94 on a rebuilt motor, the car runs great! Except for third gear and on, at 2500 rpms, the car studders spits and pops anything than 25% or more throttle.



Background on the car; 94 rebuilt JDM motor (guy bought another motor rebuilt it as the one in the car was going out). What been done to the car; GReddy FMIC, (no GReddy intake elbow though), 3in" downpipe with center cat delete, koyo radiator, 3in Racing beat exhaust, GReddy BOV, that should be it engine wise.



What I've done, added ground straps, replaced the fuel filter, rewire fans to IGN.



So first and second will go through 2500 and on like normal, in third, fourth, and fifth, she'll sputter at 2500 rpm. But lets say I take second to five thousand RPMs, shift into third, and I'll be higher than 2500 rpms, and the car runs perfect. If I'm at 2500 rpms, I can add about 10% throttle, and she'll go through it, it takes a bit but otherwise it'll go through, and this seems to end @ 3000 rpm, at 3000 rpms, I can floor her again and she'll drive normal.



The idle is good, no hard starts, no flooding. Just this stupid problem at 2500 rpms. I've tried to ground out the UIM, and I've added a few ground straps, and it feels a little better but still not perfect. I've changed the fuel filter too, and no avail. If someone could help me out where to start, or some key words to search lmk please.



Also, the motor is fresh and has about 100 miles on it, any other precautions I should take as far as break in period goes?

 

No one? I have another question, if the plug wires were swapped could this be an issue? I'm not really sure if they are put in the right order...

 

seems to be common on fd's . I have the same problem right now . i had found some information some time ago before my problem popped up . you can find some information if you look for fd's 2500 rpm hesitation . has got something to do with the vacuum hoses and solenoids if im not mistaken. In fact my problem popped up after i have rebuilt the motor and changed the vacuum hoses.

 

It is pretty normal for FDs to do that although it should not be severe. A little "hiccup" at 2500-3000 rpm is all it should be. Get a grounding kit and replace your O2 sensor.

 

i kno what your talking about, i have 4k on rebuilt and does it too, not much of a problem but just annoying. have you fixed it yet?

 

check your injectors i had a similar problem & it turns out one of my secondary injector was burn, also try changing your fuel filter it may be clogged.