P0178 code

[tater12]

while driving home, engine quits. try to restart and acts like starving for fuel. engine code is p0178 fuel composition sensor frequency low (e-85 model). Is this something that I can fix or is it a dealership issue? My repair manual doesnt give any info. auto parts store says it could be a evac issue since the sensor is not located on the fuel pump

[MeccBoy]

This would not be an EVAP system problem. Alcohol content and fuel temperature information is supplied to the powertrain control module (PCM) from the fuel composition sensor (FCS). The FCS uses a microprocessor inside the sensor to measure the ethanol percentage and fuel temperature, and changes output signals accordingly. The signal circuit carries both the ethanol percentage, and the fuel temperature within the same signal. The signal is both variable frequency and variable pulse width. The frequency signal indicates the ethanol percentage, and the pulse width indicates fuel temperature. If the PCM detects a signal less than 45 Hz DTC P0178 will set. Very high alcohal content in the fuel will cause this. Most likely the problem is with the sensor, but some diag. of the system nneds to be done.

[Freddly]

Yes, i agree it is the sensor. You can replace it yourself is you have some mechanic knowledge. The part is only available from the dealer. Depending on what year and the mileage on your truck, it could fall under the factory emission warranty so it would be a free repair.

[Chavez]

When starting My suburban [/code]after releasing key from the start position starter and engine contniues to turn over but does not crank. After 2 seconds engine and starter will quit turnover. Have to repeat several times before finally engine will run. I hear no nose out of fuel pump, No codes are set. Replaced battery and ingnition switch. What is causing the issue

[carriedi]

ok, i don't understand clearly. When you put the key into the start position the circuit engages the starter and the starter spins. it will engage the flywheel or flex plate and turn the engine over. (turn the engine over or crank the engine are both the same thing) then when the engine has all the things it needs it starts and runs.

so what does it mean when you say "starter and engine contniues to turn over but does not crank"?

what is the year of your suburban and what motor does it have?

Newer cars and trucks start different than the older vehicles. Older vehicles: when you turn the key to the start position you manually connect the curcuit to the starter solenoid. so, when you let the key go you turn the starter off.

Newer vehicles: when you turn the key to the start position you do not connect to the solenoid, you connect a circuit that talks to the computer and the computer tells the starter solenoid to start. You can let the key go and the computer will try to start the engine anyways. after a short time if the engine won't start the computer will turn the start circuit off.

Try cycling the key from off to where the dash turns on. not to the start position. you should hear the fuel pump relay cycle on and off. (two second prime) You might try listening by the gas tank to see if you can hear the fuel pump. Or you could put a fuel pressure gauge on the line and see what pressure your system builds up to.

[ral]

new here- thanks
read some of the other posts and learned some things
MY Question 2005 Suburban LT 228,000 miles Does any one have an idea on what the compression numbers for that age engine might be..... Problem if truck has sat 30 mins to an hr on startup large cloud of white exhaust--- to me that would indicate something settling in the cyln. one mechanic said it could be a couple of things rings - valve seals/seats? took it to largest Chev dealer in the area pd $109. to have it looked at. three hrs later the service writer called to say come get it-- st thing he says is you are not going to be happy with this conversation--- we recommend you replace the engine.... he is a nice guy and knew I wouldn't be doing it at the dealership-- when he told me their price he said I'm sure you may know some guys around town that could do it for you. Even at what my regular mechanic said he would charge for a used engine let alone a reman... its alot of bucks--- any comments or ideas?? I'd love to hear them all Thanks

[carriedi]

you need to verify the smoke is white. White smoke is water.

rings, valve guides, stuff like that where you are burning oil should be blue smoke.

How does the engine run? When you first start it up in the morning after sitting all night long how does the engine run? Does it feel like it's missing but it clears up after running for a while? that could be a sign of coolant leaking into a cylinder. the coolant in the cylinder will cause a misfire but as the engine warms up and burns off the miss will go away and it will run normally.

If you're burning oil, check the spark plugs and see if any of the spark plugs are oil fouled.

replacing the engine in any vehicle is going to be a bunch of dollars. 2005, you're talking about the value of the total vehicle vs putting an engine in it. If it runs good and the only exception is the smoke issue, what about letting it smoke? Or is the smoke cloud smoking up the who;e neighborhood?

What does it cost to buy a comparable truck that is running good and no smoke? would it be better to sell off this truck and invest the money into a better truck? You have to figure the price of a motor replacement vs what you can sell or trade in your truck for plus the motor replacement. let's say the engine replacement is $1500 labor and whatever for the motor $4500 (used or rebuilt, just a round about number) so somewhere around $6000. you could buy two similar trucks for that money.

try to verify what the problem with your truck is first. then decide if it is worth investing your money into it or selling it and buying something better.