Problem: Idling super rich and unstable
01-04-14, 02:45 AM
#26
Yes, you need that sensor. That exhaust sensor is the oxygen sensor. Put it back..
You also cant run the sensor check on the stock ECU. You must use the Power FC's Hand Controller to see all the sensors together and see if they are giving you signals or not.
Dont worry about the idle valve for now. Get your exhaust oxygen sensor back in the car and see what happens
You also cant run the sensor check on the stock ECU. You must use the Power FC's Hand Controller to see all the sensors together and see if they are giving you signals or not.
Dont worry about the idle valve for now. Get your exhaust oxygen sensor back in the car and see what happens
01-04-14, 03:47 AM
#27
Exhaust temp sensor is merely the cat converter overheat sensor, which is connected at the cat converter and the wire comes up through the floor. It is a silvery braided looking wire if I picture it correctly. That sensor does nothing for mixture adjustment, it merely lights the overheat light when the cat gets too hot.
What I am pointing you towards, is the oxygen sensor. It is installed in the exhaust before the main cat.
You must run the oxygen sensor. You may think it is a temperature sensor, but it is not. Without the oxygen sensor, the ECU will not go into closed loop mixture adjustment after the coolant reaches a certain point. It will run rich, and lope at idle, as your car is doing.
The oxygen sensor is a single wire, with a single terminal black connector further up the wire, towards the UIM.
See Robinette's site here for info about the oxygen sensor. This must be connected:
Replace Oxygen Sensor
What I am pointing you towards, is the oxygen sensor. It is installed in the exhaust before the main cat.
You must run the oxygen sensor. You may think it is a temperature sensor, but it is not. Without the oxygen sensor, the ECU will not go into closed loop mixture adjustment after the coolant reaches a certain point. It will run rich, and lope at idle, as your car is doing.
The oxygen sensor is a single wire, with a single terminal black connector further up the wire, towards the UIM.
See Robinette's site here for info about the oxygen sensor. This must be connected:
Replace Oxygen Sensor
01-07-14, 12:02 AM
#30
Exhaust temp sensor is merely the cat converter overheat sensor, which is connected at the cat converter and the wire comes up through the floor. It is a silvery braided looking wire if I picture it correctly. That sensor does nothing for mixture adjustment, it merely lights the overheat light when the cat gets too hot.
What I am pointing you towards, is the oxygen sensor. It is installed in the exhaust before the main cat.
You must run the oxygen sensor. You may think it is a temperature sensor, but it is not. Without the oxygen sensor, the ECU will not go into closed loop mixture adjustment after the coolant reaches a certain point. It will run rich, and lope at idle, as your car is doing.
The oxygen sensor is a single wire, with a single terminal black connector further up the wire, towards the UIM.
See Robinette's site here for info about the oxygen sensor. This must be connected:
Replace Oxygen Sensor
What I am pointing you towards, is the oxygen sensor. It is installed in the exhaust before the main cat.
You must run the oxygen sensor. You may think it is a temperature sensor, but it is not. Without the oxygen sensor, the ECU will not go into closed loop mixture adjustment after the coolant reaches a certain point. It will run rich, and lope at idle, as your car is doing.
The oxygen sensor is a single wire, with a single terminal black connector further up the wire, towards the UIM.
See Robinette's site here for info about the oxygen sensor. This must be connected:
Replace Oxygen Sensor
Last edited by Ah Teck; 01-07-14 at 12:12 AM.
01-07-14, 04:09 AM
#31
Temperature sensor on the Cat should be connected.
Oxygen sensor in the downpipe should also be connected.
Throttle position sensor should be connected.
Manifold Pressure sensor should be connected.
Coolant temp sensor (green plug on back of water pump housing near alternator) should be connected.
Idle air solenoid should be connected.
I wouldn't be adding an Apexi Neo into the mix until you sort out the underlying cause of the poor idle. Otherwise you'll have too many new variables in the situation and it will become harder to diagnose.
Our cars don't have a Karman vortex. They have a Manifold Absolute Pressure Sensor (MAP) system.
What country are you in?
Oxygen sensor in the downpipe should also be connected.
Throttle position sensor should be connected.
Manifold Pressure sensor should be connected.
Coolant temp sensor (green plug on back of water pump housing near alternator) should be connected.
Idle air solenoid should be connected.
I wouldn't be adding an Apexi Neo into the mix until you sort out the underlying cause of the poor idle. Otherwise you'll have too many new variables in the situation and it will become harder to diagnose.
Our cars don't have a Karman vortex. They have a Manifold Absolute Pressure Sensor (MAP) system.
What country are you in?
01-07-14, 04:41 AM
#32
Temperature sensor on the Cat should be connected.
Oxygen sensor in the downpipe should also be connected.
Throttle position sensor should be connected.
Manifold Pressure sensor should be connected.
Coolant temp sensor (green plug on back of water pump housing near alternator) should be connected.
Idle air solenoid should be connected.
I wouldn't be adding an Apexi Neo into the mix until you sort out the underlying cause of the poor idle. Otherwise you'll have too many new variables in the situation and it will become harder to diagnose.
Our cars don't have a Karman vortex. They have a Manifold Absolute Pressure Sensor (MAP) system.
What country are you in?
Oxygen sensor in the downpipe should also be connected.
Throttle position sensor should be connected.
Manifold Pressure sensor should be connected.
Coolant temp sensor (green plug on back of water pump housing near alternator) should be connected.
Idle air solenoid should be connected.
I wouldn't be adding an Apexi Neo into the mix until you sort out the underlying cause of the poor idle. Otherwise you'll have too many new variables in the situation and it will become harder to diagnose.
Our cars don't have a Karman vortex. They have a Manifold Absolute Pressure Sensor (MAP) system.
What country are you in?
01-15-14, 11:22 AM
#46
Recovering Miataholic
I just think the last thing that will cause unstable idle EGR valve! I went to check to see!
And yes, at one time our '94's engine idled roughly because of the EGR valve malfunctioning.
01-16-14, 05:21 AM
#47
Ah Teck, if your FD has an original EGR valve gasket, it should be updated to the later version, or else the EGR path should be blocked off altogether. Rotaries don't need EGR to reduce NOx emissions (which is why they were added to internal combustion engines). The reason is that there is already a lot of "EGR" just due to the port timing. See our 2012 emission test results with the EGR completely removed and blocked off.
And yes, at one time our '94's engine idled roughly because of the EGR valve malfunctioning.
And yes, at one time our '94's engine idled roughly because of the EGR valve malfunctioning.
Last edited by Ah Teck; 01-16-14 at 05:26 AM.
01-16-14, 06:33 PM
#48
Recovering Miataholic
wstrohm stock ecu can remove the egr valve ?
01-18-14, 05:42 AM
#49
Yes, as I wrote above. In your case, just replacing an original EGR gasket with the new style (that I linked above) would probably solve any idle issue caused by the EGR system. If you want to remove the EGR system altogether (like I did), you need to block off both the exhaust and intake holes seen when the EGR valve is removed. If you have a non-California 1993 FD, that is all you have to do. If you have a California 1993 or any 1994 or 1995 US FD, you would need to modify the EGR sensor circuit. If not done, those models would generate an engine fault light. Since we have a '94, I removed the EGR valve, blocked the holes, and made a circuit to prevent the fault indication.
