Runs lousy, have replaced all the temp. sensors,injectors,map,itack, complete tune up, only has 49k but I"m ready to junk it.....doesn't show any codes in computer, have been to four different shops, no vac or fuel leaks.. has black coating around fuel tank cover?? runs lilke its fuel starved when pushed to upper rpm scale////??? helllllllllpppppppppppp
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O2 sensors reads the amount of left over fuel in the exhaust and converts to a voltage signal so when voltage is around .800mv this is a rich condition and computer is commanding less fuel and .200mv is a lean condition computer is command more fuel. for rich condition problems check the following components. Fuel pressure regulator, leaking injectors, mass air flow meter, engine coolant temp sensor, map sensor.for a lean condition check engine vacuum leaks, exhaust leaks, air injection, map sensor, mass air flow sensor,fuel pressure regulator, fuel filter,injection
You may not have all the things I list. these are things that will make an engine run rich. ECM, 02 sensors, map sensor, mass air flow sensor, vacuum leaks, throttle position sensor, Clogged air filter, Clogged catalitic converter. You have already replaced the injectors and the ECT , so that rules them out. Check for codes. Start with vacuum leaks. Hoses and the intake manifold gaskets. If you need more info let me know. Randy
Usually it's the O2 sensor, but the fuel regulator could be stuck in the high output setting for heavy demand. Or the computer could be acting up. if you can, take it to the dealership, and have them test the computer, and the fuel regulator.
Black Engine running rich Possible Failure
-Map sensor, fuel injector or fuel pressure regulator.
Blue -Replace Faulty Transmission modulator valve
White Possible Failure. -Head gasket.
Hope this tip helps.
Check MAP sensor make sure that the vacum line going to it is good and not leaking, if you have a scan tool you could check voltage should be about 1.10 volts at idle and go up to 5.0 volt's at full throttle, also check your CTS (coolant temp. sensor) but you will need a scan tool, both of these sensor act like a chock also have your catalitic converter check if it clog it will run rich also, being if not enough air can go out, then not enough air can come in, to much gas not enough air.Hope this was very helpful.
If you are referring to the temp sensor at the intake or the oxygen sensor at the exhaust, it may cause it to flood. There could be several causes. But usually the problem may be traced to the MAP sensor or to the injectors. If the sensors are the issue the mixture would either be rich or lean. If the flooding is that bad I would check first the injectors. Have it cleaned out first and do a physical inspection on the parts.
DTC - 13
Oxygen sensor circuit open or no activity DTC - 33
MAP sensor circuit error (signal high indicating low vacuum) DTC - 54
Fuel pump circuit low voltage
Start with checking the wire leads to the O2 sensors and MAP sensor. Look for any damages to the wire harness and replace any parts damaged or faulty.
The O2 and MAP sensor take reading and sends it to the ECM to recalibrate the fuel injector pulse to adjust the amount of fuel entering the cylinders. When there is an issue to the O2 sensor or MAP sensor and even both, the ECM will be set a a factory default to run rich to keep the engine running and at times the engine may not even run. Normal fuel to air ratio is 14.7:1 - 14.7 air to 1 parts fuel and at default it could be as high as 12.5:1. Good luck and keep me posted, be glad to help you get your truck running 100% again soon and please rate. replacing the thermostat and temperature sensor would also be a good thing since the 4.3 runs best at 190".
First thing you need to do is have a code check done (most larger parts stores do this free) For the time being, ignore any O2 sensor codes...Usually that sensor reads rich condition and if too severe it throws a code of it's own but it may be false. Pay attention to temp sensor, manifold temp sensor and other fuel management items. Also, check your fuel pressure regulator...if malfunctioning default is full pressure.