Here are the MAF, AFR, and rpm data vs time for cold start and engine full warm. For the cold start condition, the afr starts swinging up and down when the ECU goes into closed loop mode. For temperatures below probably 40F, the swings can become great enough that the engine will stall. If I compare the position of the spikes in MAF voltage, rpm, and AFR, it appears that the spike in the MAF voltage just slightly precedes the spike in the AFR data. That would suggest to me that the AFR is affected by the MAF signal. It would seem more logical to me though that the afr fluctuations are preceding the MAF and rpm spikes. I would have guessed that the ECU is trying to lean out the afr, and the lean condition is killing power which causes the rpm to drop and the MAF voltage to drop. Anyhow, as best as I can tell, the car doesn't stall during warmup if the air temp is above about 40F.
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Mychailo
:: 2006 Silver Mitsubishi Evolution 9, E85, 34 psi peak, 425wtq/505whp DJ ::
1995 Laguna Blue SVX L AWD 5MT (sold)
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SVX Mods: ND iridium spark plugs, Impreza RS fpr, afr tuned to 13.2:1 using a custom MAF bypass, custom exhaust, WRX 5MT w/ STi RA 1st-4th gear & stock WRX 5th gear, Exedy 13 lb flywheel & Sport Clutch, STi Group N tranny & engine mounts, urethane spacers in rear subframe, rear diff mounts, and pitch stopper, SVX Sport Strut Springs (185f/150r), custom 19 mm rear swaybar, urethane swaybar mounts, Rota Torque 17x8", 225/45-17 Proxes 4 tires, Axxis Deluxe Plus organic brake pads.
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