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AKADriver · 01-31-2023, 01:00 PM

I've got a high idle only when coming to a complete stop. Idle is set correctly with the TPS pulled, and is normal if I clutch in while coasting, but as soon as indicated speed drops to zero, it jumps up to around 250 rpm above where it should be for the engine temp.

It's an original 5 speed late '93 S13 KA. Mostly stock configuration except the PAIR system is removed.

I'll try unplugging the EGR/EVAP solenoid to see if that's what's doing it, but the behavior seems opposite of what I'd expect if that circuit is the culprit - the solenoid should be open pretty much only while coasting down and closed otherwise.

It's not a leaky brake booster or booster hose or check valve, nothing changes if I get on/off the brake pedal. It's entirely dependent on indicated speed. Power steering pressure sensor is installed and working. A/C is off (duh).

My only other thought is someone somehow put an auto trans ECU in it for some reason and it's idling up because it thinks it's in Drive? I never bothered to look at the ECU ID. I only took it out once, way back in 2017 when I bought the car. Or could any of the manual transmission gear sensors have anything to do with it? It's got the reverse, neutral, 4th, and 5th sensors, reverse sensor works, one of the four seems to have a slight oil leak and I wonder if it's flaky.

01-31-2023, 01:00 PM	#23835
AKADriver Post Whore! Join Date: May 2002 Location: Springfield, VA Age: 42 Posts: 3,475 Trader Rating: (1)	I've got a high idle only when coming to a complete stop. Idle is set correctly with the TPS pulled, and is normal if I clutch in while coasting, but as soon as indicated speed drops to zero, it jumps up to around 250 rpm above where it should be for the engine temp. It's an original 5 speed late '93 S13 KA. Mostly stock configuration except the PAIR system is removed. I'll try unplugging the EGR/EVAP solenoid to see if that's what's doing it, but the behavior seems opposite of what I'd expect if that circuit is the culprit - the solenoid should be open pretty much only while coasting down and closed otherwise. It's not a leaky brake booster or booster hose or check valve, nothing changes if I get on/off the brake pedal. It's entirely dependent on indicated speed. Power steering pressure sensor is installed and working. A/C is off (duh). My only other thought is someone somehow put an auto trans ECU in it for some reason and it's idling up because it thinks it's in Drive? I never bothered to look at the ECU ID. I only took it out once, way back in 2017 when I bought the car. Or could any of the manual transmission gear sensors have anything to do with it? It's got the reverse, neutral, 4th, and 5th sensors, reverse sensor works, one of the four seems to have a slight oil leak and I wonder if it's flaky.