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2G 95 Eclipse GST with very rough idle and rough driving before 2k. Also extremely lean mixture at those rpms

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Al637

Proven Member
48
7
Oct 17, 2023
Central_America
Hi, I know this might be answered in another post, but I didn't found one with my specific situation or data. The car has this intermittent problem where sometimes it can idle, but most of the time when it warms up the idle starts to fail.

When the failure occurs, the air temperature rises to 150°C and the MAF stops reading airflow. It seems to me that at idle it should be at 2 or 4 g/s, but when the failure occurs it reaches 0, and due to that the AFR goes to 20+ where the wideband even stops reading. I have already tried it with a friend's MAF and the car behaves the same.

This is my first turbo car and I would like to know if anyone has had the same problem or where I should start. The spark plug wires are new, the air filter is in good condition and the car behaves very well when it enters boost.
 
If your air temp maxes and airflow drops to zero then you loses a power or ground to the MAF. Or you have a short. You should start at the MAF and work your way back to the ECU. First check if you have power/reference voltage and grounds then check your wiring integrity.
 
I will check the wiring
Another thing that happens and I'm not sure if it's normal, I have tried pressing the gas to WOT to let more air or the engine to get more rpms, and almost immediately after I do that the boost gauge reads ambient pressure.
 
I will check the wiring
Another thing that happens and I'm not sure if it's normal, I have tried pressing the gas to WOT to let more air or the engine to get more rpms, and almost immediately after I do that the boost gauge reads ambient pressure.
Well when you open the throttle blade fully there is no restriction to create a vacuum. This is normal.
 
Thanks
The car is also showing the P1105 code, which is related to the fuel pressure selenoid. I know the FPS is bad, but I have seen a lot of people connecting the fuel rail vacuum line directly to the manifold.

Since I was going to do the same I thought of using a dummy resistor and connect it to the FPS connector, I did that and with a 50 ohm resistor and for some reason the code gets back.

Is there other way for the ECU to detect that the fuel pressure solenoid is bad?
 
no the ecu sends the 5v reference and if it senses and open circuit it throws a code. im not familiar with the resistance of that sensor to say if thats the corrrect resistance

there could be a problem with the ecu or with the wiring

may want to remove the ecu and inspect the internals for corrosion from leaking capacitors
 
I've not been able to figure out what is the problem with the intake temperatures.
This is a video of how the air temp behaves taken from the OBD2 scanner
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I think the problem is the ECU, I tried measuring continuity between pins in the MAF plug, without the ECU being plugged and there wasn't any shorts between pins.
I also measured the voltage being fed to the IAT and it wasn't constant, so I'm almost sure that's the problem.
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