2009 Cadillac STS-V Flex Fuel Sensor

[northstarV]

Hello everyone,

I have been doing some research on adding a flex fuel sensor on my 2009 Cadillac STS-V and it seems to be rather difficult with the OS 12628912 that my E67 has. I was wondering if anyone has successfully done it on a STS-V? Looking between my tune and the sample 2009 CTS-V which has OS 12632176 tune that I was given, the sensor parameters are different. Mine is in % values and the CTS-V is in Hz values. Is it possible to merge OS's to run the proper parameters for the sensor?

Thank you in advance!

[07GTS]

there is no difference between them just different values, the % is ethanol, the hz is just the sensor output for the same % ethanol

[Cringer]

Hello everyone,

I have been doing some research on adding a flex fuel sensor on my 2009 Cadillac STS-V and it seems to be rather difficult with the OS 12628912 that my E67 has. I was wondering if anyone has successfully done it on a STS-V? Looking between my tune and the sample 2009 CTS-V which has OS 12632176 tune that I was given, the sensor parameters are different. Mine is in % values and the CTS-V is in Hz values. Is it possible to merge OS's to run the proper parameters for the sensor?

Thank you in advance!

I would not sweat it. The sensor sends a frequency corresponding to the ethanol percent, it is linear:
50 Hz = 0%
51 Hz =1%
...
100 Hz = 50%
...
149 Hz = 99%
150 Hz = 100%

The default frequency/percentage is used if/when the sensor fails (sending a 0 Hz signal to the ECM), this is allowing you to default the ethanol content as a backup. I would suggest a lower percentage is better since it won't try to advance spark timing (worse than going lean in CL). So defaulting to 10% or 60 Hz would be normal for most US pump gas...unless you always run a higher/specific blend.

Be sure to turn on the DTC's for the flex fuel sensor too.

[northstarV]

Okay sweet, thanks for the replies. I ordered a new Continental/GM sensor, plug, and fuel line connector to plumb it in. I'll post my progress of what happens when I get the parts in and the new tune flashed.

[northstarV]

Alright so I wired and plumbed the sensor in, and I am not able to get the Scanner to log a frequency or percentage. In my tune file I enabled Flex Fuel sensor under Engine -> Fuel -> Flex Fuel -> General, Flex Fuel - Enabled, and Fuel Sensor - Sensor. Under Fuel Sys -> Diagnostics -> Sensor Diag - Enable. I enabled P0169 - Incorrect Fuel Composition, P0178 - Flexible Fuel Sensor Circuit Low, and P0179 - Flexible Fuel Sensor Circuit High. I was also getting a P0178. The wire is pinned into Pin 5 on J1 on the E67 ECM. I attached a log and the tune I uploaded to the car. Anyone have any ideas?

[Cringer]

Alright so I wired and plumbed the sensor in, and I am not able to get the Scanner to log a frequency or percentage. In my tune file I enabled Flex Fuel sensor under Engine -> Fuel -> Flex Fuel -> General, Flex Fuel - Enabled, and Fuel Sensor - Sensor. Under Fuel Sys -> Diagnostics -> Sensor Diag - Enable. I enabled P0169 - Incorrect Fuel Composition, P0178 - Flexible Fuel Sensor Circuit Low, and P0179 - Flexible Fuel Sensor Circuit High. I was also getting a P0178. The wire is pinned into Pin 5 on J1 on the E67 ECM. I attached a log and the tune I uploaded to the car. Anyone have any ideas?

I would ensure you have a good ground connection for the sensor, how good are you with a DVOM? Or maybe try a different ground location.

[northstarV]

I would consider myself pretty decent with a DVOM. I tested voltage at the battery and at the sensor and it was exactly the same, I have the ground right on the engine block and the power for the sensor at the fuse box terminal for now, while I'm testing. If I can get it work then I'll rewire for switched 12v. I do have voltage coming out of the sensor as well. Still no % or frequency in the Scanner. I'm not sure if it could be an OS problem? Reason I'm thinking that, based on the other guys that have these cars, they have all seem to have gone down the same path as me and ended up with the ECM not reading the valid signal from the sensor.

[07GTS]

not sure if engine block is good for an earth, i used the earth to the ecu when i put the signal wire into mine so its a know good loop, also put the enable delay to 10 sec not 60 sec see if that helps otherwise it may not work till after 60 sec test

[northstarV]

I'll swap my ground around tonight along with changing the diag delay and see if it does anything. Is it possible to merge OS's or is it more trouble than it's worth?

[hjtrbo]

Check for for frequency out of the sensor.

[northstarV]

I just checked, I was getting 59.9Hz so about 10% ethanol coming out of the sensor. Power and ground were reading exact battery voltage as well. I also checked to make sure it was firmly installed in Pin 5 on the smallest connector which it was. I'm kind of at a loss here.

[07GTS]

sure its pin 5 of J1 (blue) ECM plug ? also put ur delay volume to 0 and the transition to 0 for a test, max ethanol can be 80% that value is for the table blending not actual ethanol, at the moment u have to use almost a liter before it will change over all the way, then u have to set those properly to suit the use of fuel in the lines from the sensor to the injectors, but see if that helps first

[northstarV]

Yes, I have it in pin 5 of the blue plug, I checked the wiring diagram and confirmed it was next to the wires it was supposed to be in the connector. I also changed those values and no change. It doesn't even read anything in the Scanner 0% and 0Hz but it has confirmed function with a DMM at 60Hz which is within range of 50Hz to 150Hz. I disconnected the sensor from the ECM and the exact same DTC P0178 came up whether it was hooked up or not.

[07GTS]

also change ur stoich table back to stock, flex wont work it its all 14.7 see if that helps, that dtc is for circuit low which is usually a short to earth in the signal wire so not sure whats going on there

[northstarV]

Yeah, I checked all the wiring before I took it off last night and it all seemed good. I would've thought it would output something in the scanner but I guess not. A few other guys with these cars had the same problem I think including the two companies I bought the performance parts from. https://www.cadillacforums.com/threa...roject.889578/ Post #23 is who I sourced my parts from and he had the same issue going on.

[07GTS]

strange, maby contact hpt support with all the data and see if it something they can add or at least tell u its not supported by ur ecu or something then u now whats going on

[northstarV]

I'll send them an email and see what they think of it.