Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
Hi, I was working on a friend's 2012 tacoma with a 4.0. Engine light was flashing so I told him park it and I would check it out for him. Turned out it had a fried coil on no. 4 . No biggie , put a coil on it and light is off and stayed off. The oddity I have a question about is; I have an autel mp808 and it starts in open loop , switches to closed loop fine but when I snap the pedal it changes to open loop drive. Looked briefly on Toyota Nation and oddly no threads but did find a bmw thread that heavy loads or cruising it can switch to open loop drive. This happens on the toyoya in park just snapping the pedal, even lightly . Is open loop drive a normal mode on a Toyota or does it indicate it not being able to stay in closed loop under demand ?
No codes, lt is -5 on b1 and 1 on 2, uneven but not bad for 180,000 with the original plugs in it and one new coil on b2. Was in his work parking lot and the miss followed the coil swap, no one wants to be busted down at work so I just changed the coil to get him home.
Another oddity I do not know if it is the autel or the truck but under the Toyota live data there is no rpm signal, the coolant sensor temp flutters from -30 to 200ish even cold and the vehicle speed starts at 1 and counts like a stopwatch until it said the truck was goin 140 in park , even the miles since cel add up like it is moving . The tach in the truck reads 700 but 0 on the scan tool . I switched to global before doing anymore and there was the rpms, and the correct 0mph in park. The one thing that remained the same is when I give it around half a pedal it goes into open loop drive . Initial start up is just open loop in both modes, open loop drive when given gas in either. Any ideas? Thanks in advance
Closed loop control using HEGO feedback (two states; rich or lean) is centered around stoichiometry by using an adaptive jump-back strategy that is designed to oscillate between rich and lean at part throttle in order to maximize the exhaust catalyst cleaning effect of the catalytic converter in order to meet tail pipe emissions.
However, during tip in the engine will have a very fast lean excursion and stumble if fuel is not added quickly and at a very rich mixture. With carburetors this function was performed by the accelerator pump, which basically just injects more fuel in the air stream above and beyond what the engine vacuum is demanding. A fuel injection strategy will use rate of change of throttle to provide a momentary rich mixture to compensate for the momentary lean condition. How rich depends on the engine operating point and the magnitude of the tip in.
Normally, the closed loop fuel control will be turned off (go open loop) while the tip in event is active. After the tip in the engine will once again try to achieve closed loop fuel control.
