Hey guys, after countless hours of reading and messing around with this car for about a year I finally gave up and figured I'd post on here.

2001 w/ original 80k F20C engine

Here's the situation:
- Cold start, first drive zero issues.
- Heat soaked (after a track day, during a track day in the pits, after I drive it and let it sit for a while) = car will stall coming up to a stop sign/stop light when the clutch is pushed in. I can negate this by doing a very, very gradual in-gear coast down and push the clutch in at ~1k. But if I'm in the pits coming up to grid and have to push the clutch in first gear the revs will fall and either stall or almost stall. In the case of my last track day even after a long drive on the interstate home, it never stopped doing it. So I really believe it only does it when the engine has been completely heat soaked. For example, leaving it sit for a few hours with the hood open it will not do this when you drive it again. It should be noted that sometimes it just idles low when I perform this maneuver and figures itself out. I've read that I shouldn't blip the throttle to keep it alive, so I don't. It should also be noted that when it does stall, it doesn't even TRY to hold it up. Just straight to 0.

What I've tried so far:
- Cleaned IACV (disassembled, carb cleaned, spun the rod)
- Cleaned Throttle body + channels to the MAP sensor + new TB gasket
- Checked all the vacuum lines I have left (PCV is capped as well as the air pump deleted). I did find that the air pump capped piece on the intake manifold was melted away in a part, but replacing this did not fix my issue. I blew into all the lines and pressure held just fine (gross).
- ECU relearn procedure (though I did not do it after I fixed the potential vacuum leak @ the air pump nipple)
- New spark plugs gapped at .042" (left them at their natural gap)
- Checked VTEC solenoid for debris (none found, probably rules out thrust bearing)
- Valve adjustment (they were a little tight, had a local member help me and verify)
- Installed new IAT sensor
- Checked TPS voltage at throttle closed (.26V) and WOT (4.46V)
- Sprayed all joints/hoses w/ Propane to look for vacuum leaks
-Uninstall Greddy Emanage
- Primary O2 Sensor
- smoke test (no leaks)
-replace injectors with another set of used injectors
-replace idle air control valve
- Checked crank end play (.006-.007" measured)
- Replace fuel regulator
- Replace Fuel pump + strainer
-Adjust TPS
- Compression test (135/140/145/145)
- Removed evap circuit

EDIT: FIXED. Exhaust Manifold cracked runner to flange stalling issue is fixed. /Thread

 

Could you just clarify please: there was a potential vacuum leak at the air pump nipple - do you have a pic or could you describe it to me more precisely. I might want to take a look at mine just in case.

A new IAT sensor might solve the issue. Only one way to tell though, unfortunately. Even in hot weather my AP1 wouldn't cut out when coming to a stop after the ECU learned its idle correctly. I did notice the revs dropping a little too low at times but it would bring them up again gradually without me having to tap the accelerator pedal.

 

Oxygen Sensors?

 

Yes. The potential vacuum leak was, looking from the drivers side, the farthest small nipple towards the firewall on the intake manifold. It had a cap on it, but the cap was melted on the underside most likely due to poor material choice. I'm not sure it wasn't sealing still but I replaced it anyway.

Well I get the IAT sensor today so I plan on throwing that in and seeing what happens.

Last night I checked the purge valve as well, it is not stuck open at least with engine off.

 

No code for it and, even being primitive, I assume I'd throw a code. They're cheap so I could try it I guess though if all else fails.

 

mine did the same until I did a proper idle relearn from fully cold. also after the relearn was done, the first 10 miles or so, I down shifted and coasted into low rpms, now blipping throttle or coming to a stop it never dips ever.

 

By proper, you mean:
1. Disconnect the battery, push the brakes to get all the power out of the system
2. Cold start, hold to 3k until the fans come on
3. Let it idle for 5 minutes not counting the fans on-time

Sound about right? Or am I missing something?

 

yep thats it. make sure fans, ac, radio, lights all off too(figured you knew this just mentioning it)

and right at the end take it for a spin, bringing revs up and back down to almost idle coasting in gear a couple times. after a mile or two turn everything on(radio ac, lights etc) and drive like normal. it should drive and idle perfect now

if it starts to falter at idle coming to stop don't help it with the pedal, it should catch it and learn. this should only happen once or twice if at all, and then it shouldn't do it anymore (learned)

good luck!

 

I'll give it another shot today after the new IAT sensor. I got a volt meter to check the TPS throttle closed value as well.

 

Do you have a light flywheel?

A good idea is also to perform a compression and leak down test.