Erratic idle, shut off and code P0193

Tiny
RUNOXX
  • MEMBER
  • 2004 FORD EXPLORER
  • 4.0L
  • V6
  • 4WD
  • AUTOMATIC
  • 205,000 MILES
One day I was on the highway and the accelerator stopped working for like two seconds then came back. I then got off the highway and ended up at a stop light and the vehicle had an erratic idle, jumping up and down so I put it in park, and started to rev a little bit to prevent it from stalling. I pulled off the road and the vehicle shut off, I started it back up and everything was fine. I got it home and seen that I had a fuel rail pressure code P0193 and system too lean bank 2 P0174. I hooked up my scan tool and measured fuel trims, fuel pressure and MAF sensor readings. I will put a picture below. Looking at the data I know STFT isn’t supposed to be so high, also fuel pressure is way too high, usually it’s 39-40 PSI. MAF sensor readings also don’t seem right either. I assume I need either a fuel rail pressure sensor, a fuel filter or MAF sensor or all three? I should also state that after resetting the codes and starting up the vehicle is stalled within seconds, and I got the Fuel rail pressure code but not the bank 2 too lean code. Any help is appreciated.
Monday, April 4th, 2022 AT 12:48 PM

2 Replies

Tiny
WENDY W
  • MECHANIC
  • 86 POSTS
Hello,

The P0193 code could be related to the fuel rail pressure sensor or its circuits. Have you been able to check the connector to make sure the sensor is plugged in properly, and that there's no corrosion in the sensor connector or any damaged wiring?

Below you'll find several charts that will help you check for reference voltage at the fuel rail pressure sensor. You should see 4 to 6 volts between the VREF and SIGRTN terminals with the key in the "on" position.

I've also attached the removal and replacement procedure for the fuel rail pressure sensor in case you need it.

Also, these two repair guides help give a nice overview on how to check fuel pressure and what to expect when changing the fuel filter:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/how-to-change-a-fuel-filter

Please let us know if there's anything else we can help with.

Thanks, Wendy W.
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Tuesday, April 5th, 2022 AT 1:37 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This code is pointing to a fuel pressure sensor, so we need to start with this testing.

I don't always trust those readings on the scan tool because they alone can mislead us. So, if we run through the testing and it points to a sensor as well then this would be more evidence of it needing replaced. However, I have seen many scan tools that just don't read the sensor correctly which leads to replacement of it improperly.

Here are a couple of guides that will help with this testing:

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Let's run through this testing and see what turns up. Let me know if you have questions. Thanks
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Tuesday, April 5th, 2022 AT 2:10 PM

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