AndyLowe

I have not had these symptoms, but wanted to weigh in on some ideas for you: - If you purchase a subscription to www.alldatadiy.com, you can learn from the ECM wiring Diagrams which small pins to monitor on the rectangular Diagnostic Connector, mounted on the top of your engine. I would recommend, have the engine at idle, normal temp and with a volt meter, set on DC 1 volt range, sample the two or four O2 Sensor readings. Connect your volt meter red lead to these pins, one at a time, and the black lead to ground on your engine. You want to see each O2 Sensor voltage porpoising slightly above and slightly below half of one volt, while engine is warm and idling. If you have O2 sensor readings that are always above .5vdc, they are indicating RICH mixture in the exhaust, back to your ECM. (Electronic Control Module, Brain, Computer) Lean exhaust is Low Voltage; below .5vdc. (.2, .3, .1, .4vdc) Lean would indicate a Vacuum Leak. Rich might indicate a ruptured Fuel Pressure Regulator Diaphragm or blocked air passage at the throttle plate, or Idle Air Control Valve, Bypass air route. - Because you lack power and have an EGR code, I would also recommend a nice tool, called a Back Pressure Gauge. I bought mine and rarely need it, but it is cost effective, when compared to an innacurrate diagnosis at a local shop. If you buy a Snap On EPV311A Vacuum/Pressure Gauge Set, you remove one O2 Sensor and install this tool. Now you start your engine and simply don't EVER want to see over 3 PSI when at idle or driving on the highway. (Simulate this with pressing the accelerator pedal and raise engine RPM to a similar highway speed. This will quickly eliminate or condemn the mufflers and catalytic converters. These are suspect for your low power, based on the parts you've recently replaced. Have you really opened up and inspected your Air Filter? I've seen one car a long time ago, that sucked up a plastic bread bag and reduced airflow across a semi clean air filter to approximately 30% airflow. I hope this helps~ Andy The O2 sensors are indicating ~2.25 volts or higher when the engine is warm and running rough - indicating that the fuel is running rich. I put a vacuum gage on the Fuel Modulator inlet and can see that the inlet vacuum is fluctuating up and down in rythm with the engine surging while running rough. A question is what would cause the engine to run rich and the inlet vacuum to fluctuate? O2 Sensors, are Thermo Couples. They are incapable, by themselves, of creating 2.25 volts from my experience. ( I could be wrong). Today's Modern O2 Sensors, have Heater Elements to accelerate the ability of the 02 Sensor to begin reporting useful data (voltage) back to the ECM. These Heater Elements live within the O2 Sensor, and warm them up, even when the exhaust has not risen to normal temperature. A properly operating, Heated 02 Sensor, will warm up quickly, and begin giving reliable/useful voltage inputs to the ECM for proper fuel mixture calculations. Heated 02 Sensors reduce bad emissions, overall, as they get the mixture correct quickly, from first start of the day. When a Heating Element partially shorts to the 02 Signal Line, which normally porpoises around .5vdc, it caused this normally low voltage level to be above 1 volt. In your case, you have a partially shorted heater element, on one of your 02 sensors, partially shorted to the 0s Signal, back to the ECM. Others may correct me, but I have never seen an 02 signal above .9vdc, ever. The ThermoCouple (02 Sensor)is incapable of a voltage above .9vdc. Your Rectangular diagnostic connector, on the top of your engine has a flip open lid/cover. Within this Lid is a legend for pin assignment and purpose. Find the two or four different 02 Sensor pin assignments, start and run the engine, let it get warm, and compare the four. I think you will see only one of them is above .9vdc; your defective, heater element shorted 02 Sensor. Disconnect one 02 sensor at a time, to determine which one is THE one, when the volt meter goes to zero. You will fix this! My email is andylowe@sbcglobal.net Andy

Von, I'm curious if you solved your Igniter Puzzle? My 94 LS400 had a bad ECM (Power Train Computer Module) as it would have erratic voltages to the passenger side Igniter when key was on (no need to put key in Start position). My ECM would instantly rise to 2.2vdc, for Igniter 2, when key was ON, and this was wrong. When you turned the key to start, the voltage would drop to zero and occasionally have a square wave output from the ECM of 2 volts, but not nice and even like the output to Igniter # 1. You can swap the harness connectors at the Igniters, to eliminate if you have a bad Igniter. My problem was no spark on the passenger side of the engine, and a new coil and Igniter did not fix this. When I monitored and compared signals from the ECM to both Igniters, I saw the difference. Opening the old ECM revealed a couple leaky Capacitors, but who really knows if that was the cause. I suspect a poor transistor moreso. I bought a ECM from a Salvage yard for $50 and it started right up. Andy

I have not had these symptoms, but wanted to weigh in on some ideas for you: - If you purchase a subscription to www.alldatadiy.com, you can learn from the ECM wiring Diagrams which small pins to monitor on the rectangular Diagnostic Connector, mounted on the top of your engine. I would recommend, have the engine at idle, normal temp and with a volt meter, set on DC 1 volt range, sample the two or four O2 Sensor readings. Connect your volt meter red lead to these pins, one at a time, and the black lead to ground on your engine. You want to see each O2 Sensor voltage porpoising slightly above and slightly below half of one volt, while engine is warm and idling. If you have O2 sensor readings that are always above .5vdc, they are indicating RICH mixture in the exhaust, back to your ECM. (Electronic Control Module, Brain, Computer) Lean exhaust is Low Voltage; below .5vdc. (.2, .3, .1, .4vdc) Lean would indicate a Vacuum Leak. Rich might indicate a ruptured Fuel Pressure Regulator Diaphragm or blocked air passage at the throttle plate, or Idle Air Control Valve, Bypass air route. - Because you lack power and have an EGR code, I would also recommend a nice tool, called a Back Pressure Gauge. I bought mine and rarely need it, but it is cost effective, when compared to an innacurrate diagnosis at a local shop. If you buy a Snap On EPV311A Vacuum/Pressure Gauge Set, you remove one O2 Sensor and install this tool. Now you start your engine and simply don't EVER want to see over 3 PSI when at idle or driving on the highway. (Simulate this with pressing the accelerator pedal and raise engine RPM to a similar highway speed. This will quickly eliminate or condemn the mufflers and catalytic converters. These are suspect for your low power, based on the parts you've recently replaced. Have you really opened up and inspected your Air Filter? I've seen one car a long time ago, that sucked up a plastic bread bag and reduced airflow across a semi clean air filter to approximately 30% airflow. I hope this helps~ Andy