RPM's hang when rev'ed in neutral

[2.2TLegacy]

Just curious what might make the RPM's hang when reving the car in neutral. Also happens when coasting to a stop and going from first to neutral (not on the throttle, just coasting) revs hang at 2k and then slowly drop to idle. Only happens between first and neutral and when in neutral.

Again, I searched and didn't find anything relevant to my issue.

[vrg3]

You don't say anything about what your engine setup is.

If the combination of your IAC valve, TPS, and ECU is not all stock, or either the IAC valve or TPS are miscalibrated, that could cause this weirdness.

The ECU does sometimes keep engine idle speed high when you're coasting; I believe this is to ensure that the power steering and power brakes work effectively as you coast to a stop.

[2.2TLegacy]

Stroker EJ22, Weisco forged internals, ej20g heads, vf39 sti turbo, 1996 jdm spec Sti tranny, stage 3 puck clutch with lightweight flywheel (can't remember brand right now). Sensors and ecu are all stock ej22t sensors.

I am just more curious than anything if there are a few quick potential fixes, it doesn't bother me that much.

[vrg3]

Hrm, well, I don't really know any more than what I said above... It's possible that adjusting the TPS or IAC slightly might make it partly go away.

The ECU does intentionally open the IAC valve up when you close the throttle so that the engine's airflow doesn't change too suddenly (kind of performing the same function as a dashpot on older cars), so this is probably a combination of that and the steering/braking thing I mentioned above.

[Legacy777]

Did the car originally have a manual or automatic transmission?


You can try adjusting the TPS to see if it makes any difference.

http://www.main.experiencetherave.com/s ... sting3.jpg

[2.2TLegacy]

Did the car originally have a manual or automatic transmission?


You can try adjusting the TPS to see if it makes any difference.

http://www.main.experiencetherave.com/s ... sting3.jpg

originally was a manual.

[Legacy777]

Ok, just checking. Sometimes if it's a swap, the AT/MT pin isn't pinned correctly, which may cause weird idle behavior.

[2.2TLegacy]

Did the car originally have a manual or automatic transmission?


You can try adjusting the TPS to see if it makes any difference.

http://www.main.experiencetherave.com/s ... sting3.jpg

Hey josh, is the TPS on the ej20g the same as the one from the ej22t? I have the 20g intake mani and throttle body so I dont know if that makes a difference.

[Legacy777]

Is it a 4-pin TPS? If so, it should be the same.

[2.2TLegacy]

yeah its 4 pin, PN is 22633AA060