Okay, I have a jdm b16 motor I bought from hmotors. The motor had about 50k miles on it when I bought it, and I've put about 3100 miles on it so far. This might sound weird, but the car hesitates/sputters when I push the pedal in past a certain point at 2500-2700 rpm, at about 3100 rpm, and about 4000 rpm. After 4000 rpm, I can accelerate normally no matter how far I push the accelerator, whether it be to the floor or if I ease into it. My spark plugs and wires, fuel filter, walbro pump, and distributor cap and rotor have about 3100 miles on them. Can you guys think of what could be causing this like bad ignitor, coil, tps sensor, etc? Also, timing is set perfectly because my belt and tensioner were replaced quite recently as well by a friend. And I've checked for vaccum leaks as well. I don't have any. Thanks for any help you can give me guys.

 

I have also experienced random hesitation with a JDM b16. Like you I had it completely tuned up in every way. The engine ran great for years, but for some reason had the hesitation at times. Only at part throttle at lower rpm. I autocrossed with success and achieved excellent fuel mileage.

I recently discovered some burnt/worn parts inside the p30 ecu. Could have been the problem, although I dont run this engine anymore. Maybe check out your computer.

 

It's funny you should bring up ECUs. When I was using the jdm p30 that came with the swap, the hesitation only occurred at the 2500-2700 rpm point. However, I just recently bought a chipped ecu from phearable.net, and that's when the other two hesitation points came. So I really don't know what direction to go in.

 

check all electrical grounds... maybe disconnect the manifold o2 sensor completely and see if that makes a difference.

 

I know all of my grounds are good to go as well. I will look into o2 sensors though. Do jdm b16s(sir2) have 2(primary and secondary) o2 sensors? If they do, where is the other one besides the one on the exhaust manifold? Thank you.

 

Update: Went for a drive today and at certain times during the drive the car nearly came to a stand-still rpm-wise. I'd be going about 50 mph in 5th gear and the car just didn't want to accelerate any faster. I had to completely let off the gas and then push the gas back down a pretty good amount again. I also tossed out some pretty big backfires while shifting upwards to 7-8k rpm.

 

Did you TRY driving with the o2 sensors disconnected? Should rule them out entirely by driving without them attached, that way it'll be driving on pre-configured fuel trims. It'll run rich for sure but if it's still doing this issue, even to a smaller extent, you'll be able to rule that out entirely. Maybe you have a sticky IACV valve? hmm.. I dunno

 

Yeah, I plan on driving with the o2 sensor disconnected tomorrow and see how it feels. I feel like a noob. I only have one sensor. I'm running the kiddracing header right now. And my iacv is as clean as a whistle. I cleaned it twice when I was troubleshooting my roaming idle about a month ago.