heres the rundown
new NTK sensor
new header new donut gasket
stock cat
don't see any exhaust leaks
stock ecu
all new seals no coolant or oil leaks
no vacuum leaks
new spark plugs and coil and cap/rotor
valve lash adjusted twice
compression 210 in all cylinders
timing is on point

I have scangauge hooked up and when in low/mid throttle it bogs really bad in that rpm range then suddenly after 3500rpm it runs normal and vtec is good and hard acceleration is good no lag.

scan gauge shows primary o2 reading .1volt during lag and then .9 when its normal...

I just took header off and checked to see any holes in gaskets but didn't see any leaks on the header gasket or around o2 sensor

what can it be? it feels like a bad o2 or exhaust leak but I checked both already

 

Do you have a friend nearby with another stock ecu you could try swapping out with? That would eliminate that as a possibility. What kind of new header is it? I've put a Ebay header on a sohc civic before and bogged in the lower rpms.

 

that's the only ecu that I could find lol. they are hard to come by

b16a2 stock p2t ecu all stock except basic boltons

 

Check your tps and map sensors?

 

I checked with obd1 neptune ecu. no abnormal readings on any sensors.
No pending codes ever show up
and only does it at part/light throttle
If i step on it a bit harder it doesnt do it.

Could it be that tps sensor is not properly calibrated so it gives wrong voltage at part throttle/
Its a stock unmodified throttlebody but its not from this engine and ecu is also not original to this engine
i bought a longblock stock intake manifold and ecu separate on craigslist
Nothing is burned inside ecu i checked and sniffed

 

fuel filter? bad iat sensor? mis calibrated tps? I would start there, no particular order. Same thing was up with gsr before, took it for a tune and right away found out the iat was bad.

 

I replaced iat sensor and tried on intake manifold also. no luck. the iat temps look pretty consistent in scan gauge.im gonna try recalibrating the tps see if that does it.

 

forgot to add. it accelerates fine when cold. but once its normal temp it starts lagging

I mean its obvious that its fuel starvation I just cant figure out where the problem is lol

 

calibrate that TPS

.48-.5 at closed throttle and 4.5 at WOT

use the paper clip method, its the easiest way. If not that then change the fuel filter, then pump.

 

I have neptune. Already been calibrated.
It might be bad ait or both of them i switched to manifold iat and its slightly better

 

I would adjust the tps at the tps and not the ecu. Also check your dizzy make sure everything is good there. Could be the fuel pump soon as it heats up it can be cutting out, but not a specific rpm rang tho. Im guessing dizzy, crank sensor could be messing up.

 

I had that same problem

check your jacks by the ECU.
depending how the harness was run, when someone mashes that area it pulls a little and caused that problem

BTW do you have a jumper harness ?

 

As long as the ecu sees 0-100%, it does not matter what the voltage is.

From what I have experienced, The TPS is not used for fueling or ignition. It's only used as an input to the ecu. for instance, knowing when to turn off the AC compressor; when to engage fuel cut decel, vtec, nitrous control, map switching,etc. it doesn't not directly effect fueling as our EFI system uses the map sensor as primary map load.

The only time I have used the TPS for fuel and ignition control is with itb with alpha-n or straight TPS based since vacuum is so low. It can be setup to use the map sensor for idle and TPS for anything off idle, however, using TPS primary with itb is much simpler.

Anyway, your problem is likely not TPS based. I'd pay more attention to what sensors are involved between open and closed loop since your problem only shows it's face in closed loop and operates "normally" during open loop. Thus further proving why it drives better when it is cold consider it takes time for a cold engine to enter closed loop after initial startup.

 

^^good info.

 

=+1

 

have you tried doing some partial tuning in that section that your having the problem?
your either running to lean or rich since you started that you dont have the problem when the motor is cold but, when the motor is warmed up it happens. how is the air/ fuel in that area?

JD TUNING