Intermittent stalling, I'm stumped

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jja2116

New Member
This is a B16B swapped into an 00' Si. Just completed it, had it running great, was traveling for 2 weeks and now I have a weird stalling problem, and sometimes hard starting.
-If I give it gas very gradually it's fine
-When I wind it up into VTEC no problems (plenty of power)
-If I hit the throttle quick from idle or in the lower 1/2 of the RPM range sometimes it hesitates/stalls. If I take my foot completely off the accelerator it recovers immediately.

The hard starting would make me think IACV, but the fact it stalls in the 2-4k rpm range makes me think it's something else, can IACV cause problems at partial throttle? I feel like the clue is in the fact it will be running fine and when the throttle plate opens quickly letting in more air it's like it doesn't fuel it correspondingly and just dies, but then sometimes it doesn't do it at all. TPS is fine, fuel pressure looks OK, No air blockages, No codes, plugs look great.

I think the two clues are in the fact it sat for 2 weeks, and that sudden changes in throttle position cause this. Please help.
 
Time for a tune up, that would clear most factors.

change plugs, cap, rotor, pcv valve and wires. Also clean out TB, IVAC, and IM. Check for vac leaks
 
I was hoping for some magical insight beyond completely overhauling all my ignition and fueling components, many of which were done as a matter of course with the swap already. I finally figured it out, the intermittence and duality was driving me nuts and pointing at something beyond the usual suspects. Turned out it was the MAP sensor, I had checked my sensor, but it was an issue with the connector, a bad contact was causing it to flake out, and flicker. Fixed the connector, all better. Thanks,
 
Hook up a scanner and monitor TPS and MAP voltage, and check fuel pressure with KOEO and KOER.


edit: nevermind, looks like you already got it
 
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