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  • 5 Aug 2019 11:01 AM | Anonymous

    The flex fuel sensor measures the ethanol-gasoline ratio of the fuel being used in a flexible fuel vehicle. Flexible fuel vehicles can be operated with a blend of ethanol and gasoline, up to 85 percent ethanol. In order to adjust the ignition timing and the fuel quantity to be injected, the engine management system requires information about the percentage of ethanol in the fuel.

    The flex fuel sensor uses quick-connect style fuel connections, an incoming fuel connection, and an outgoing fuel connection. All fuel passes through the flex fuel sensor before continuing on to the fuel rail. The flex fuel sensor measures the fuel alcohol content, and sends an electrical signal to the engine control module (ECM) to indicate ethanol percentage.

    The flex fuel sensor has a three-wire electrical harness connector. The three wires provide a ground circuit, a power source, and a signal output to the ECM. The power source is battery positive voltage and the ground circuit connects to an engine ground. The signal circuit carries the ethanol percentage via a frequency signal.

    Alcohol content information is supplied to the ECM from the fuel composition sensor. The fuel composition sensor has a battery positive circuit, a signal circuit, and a ground circuit. The fuel composition sensor uses a microprocessor inside the sensor to measure the ethanol percentage and changes the output signal accordingly. The signal circuit carries the ethanol percentage via the frequency signal. The ECM provides an internal pull up to 5 V on the signal circuit, and the fuel composition sensor pulls the 5 V to ground in pulses. The normal range of operating frequency is between 50–150 Hz. The microprocessor inside the sensor is capable of a certain amount of self-diagnosis. An output frequency between 180 Hz and 190 Hz indicates that the fuel is contaminated.
    GM vehicles will automatically detect and calibrate to run gasoline, e85 or any blend of these two fuels. Why run e85 in your vehicle? Ethanol (or e85) is a remarkable fuel source!

    • 105 octane rating – in most cases better than 110 octane race gas
    •  Engine will run cooler with a 27 percent reduction in heat compared to premium gas
    •  Extreme tolerance to detonation, some naturally aspirated engines are able to run up to +15:1 compression ratio.
    • ETs are less affected by atmospheric changes
    •  Does not leave carbon deposits like gas, so maintenance is reduced across the board
    • Not corrosive like methanol
    • 35% more energy than methanol
    • Performance is comparable to best race gas at a fraction of the cost
    • e85 is offered at a growing number of gas stations:
    • e85 is a renewable fuel source that is also environmentally friendly

    If you are already running E85 or researching the possibility of running E85, you should be aware that the ethanol content in any gallon of "E85" you get from the pump will vary from 70%-85% ethanol depending on the time of year and what part of the country you are from.  It typically runs around 75-80% in the winter months and late spring and 85% during the summer and early Fall. Of course sometimes it even varies by the station that sells E-85!

    If your car has been tuned specifically for 85% ethanol content - you have to either adjust your tune or mix your own.  Both Ignite Racing Fuels and VP Racing Fuels sells 100% Ethanol (actually only ~ 98%) in 55 gallon drums and also probably in smaller sized drums.  You can even purchase 55 gallon drums of pure E-85 and E-90 if you don't want to mix the 100% ethanol with pump premium fuel.

    Here’s a quick reference for how much of each grade to mix with 100% ethanol to make 10 gallons of E85:

    5gal 70% + 5gal 100% = 10gal 85%
    6gal 75% + 4gal 100% = 10gal 85%
    7.5gal 80% + 2.5gal 100% = 10gal 85%

    What's your ethanol percentage?
    The ethanol content of E85 fuel can vary from 60% to 92% ethanol. A fill up with E85 can drastically change the mix of fuel in your vehicle. For performance drivers determining actual ethanol content of E85 is essential to maximizing an engine tune and horsepower.

    Why know your ethanol percentage?
    E85 has the equivalent octane rating of 105 octane gasoline. Higher octane fuel is more resistant to knock allowing for more aggressive ignition timing, higher compression and increased engine power over gasoline itself.
    Zeitronix had released an ethanol content analyzer gauge which is a new ECA gauge they have produced in both blue and red LED displays. Currently only available in the rectangular gauge, their digital electronic display is designed to show the viewer the precise percentage of ethanol contained in their fuel mix.

    Not only does this gauge work on standard gasoline which contains ethanol contect of up to 10% in today's fuel, but it also will also work with standard E85 stations, E98 mixes, home brewed mixes of 100% and anything in between.

    It is a standard practice for Ethanol stations to periodically change the exact mix of the fuel being brought from the supply tankers available at the pump. On the Ethanol pumps you will notice a sticker indicating a minimum rating of 70% Ethanol content, much like the 10% content labels on standard gasoline pumps today.

    Aside from slight variances in actual ethanol content, in many locations there is a "winter blend" major change in the content at E85 stations that take it down to the minimum 70%. They do this for improved cold start performance of the engine.

    Problem is if you have been custom tuned to the edge of performance at 85% ethanol and all of a sudden got less ethanol and more gasoline, your car would no longer be tuned for the fuel content you had originally been set up to use.

    On flex fuel N/A cars, these changes in content can be handled by the front O2 sensor which can adjust the fuel trims automatically. However on a high performance turbocharged engine with 20lbs+ of boost pressure, a 15% change in alcohol content can have a serious impact on performance and octane level.

    So if you are considering an E-85 flex fuel conversion, contact us and we will answer any questions you might have including providing you a turn-key quote which includes parts, labor and tuning.

  • 17 Jul 2019 8:02 PM | Anonymous

    Do you have low oil pressure? If so, it might be the result of one or more of the following which you can troubleshoot yourself or engage HPX to diagnose and fix the issue.

    1. Worn Engine Bearings
    2. Worn Oil Pump
    3. Weak or Leaky Oil Pressure Relief Valve
    4. Aerated Oil
    5. Oil System Leaks


    A good place to start your diagnosis of a low oil pressure condition is at the dipstick. Check the oil level to see that it is at the proper level (not low and not overfilled). If low, the engine may be burning oil, leaking oil and/or be neglected. Adding oil may temporarily remedy the low oil pressure condition, but unless the oil level is properly maintained by your customer the problem may reoccur.

    If the engine is leaking oil,  new gaskets or seals should fix the leak. If the engine is burning oil, the valve guides and seals are most likely worn, but the rings and cylinders might be bad, too. A wet compression test and/or leakdown test will tell you if the valve guides or rings and cylinders are worn. The least expensive fix in the case of worn guides would be to install new valve guide seals (if possible) without pulling the head. But the best fix would be to pull the heads and have the guides lined, knurled, replaced or reamed for oversized valve stems. Worn rings and cylinders would call for a complete overhaul.

    Also note the condition of the oil and make sure it is the correct viscosity for the application. Heavier viscosity oils such as 20W-50, straight 30W and 40W may help maintain good oil pressure in hot weather, but are too thick for cold weather driving and may cause start-up lubrication problems especially in overhead cam engines. Light viscosity oils, on the other hand, such as straight 10W or 5W-20 may improve cold weather starting and lubrication, but may be too thin for hot weather driving to maintain good oil pressure. That is why most OEMs today recommend 5W-30 for year-round driving in modern engines.

    If the oil level is okay, the next thing to check would probably the oil pressure sending unit. Disconnect the unit and check the warning lamp or gauge reading. If the warning light remains on with the sending unit disconnected, there is probably a short to ground in the warning lamp circuit. Likewise, if there is no change in a gauge reading the problem is in the instrumentation not the engine.

    Bad oil pressure sending units are quite common, so many technicians will replace the unit without checking anything else to see if that cures the problem. This approach might save you some time, but it is risky because unless you measure oil pressure directly with a gauge attached to the engine you have no way of knowing if pressure is within specifications or not. Most warning lamps won't come on until oil pressure is dangerously low (less than 4 or 5 lbs.). So don't assume the absence of a warning lamp means oil pressure is okay, especially if the engine is making any valve or bearing noise.

    If a check of oil pressure reveals unusually low readings, check the filter. It is possible the filter might be plugged with gunk. Ask the customer when he last had the oil and filter changed. Or, replace the filter and see if that makes a difference.

    The next step would be to drop the oil pan and check the oil pump pickup screen. If the screen is clogged with debris, you have found the problem. Also, check to see that the pickup tube is properly mounted and positioned, firmly attached to the oil pump (no leaks) and is not obstructed.

    If the oil pump is mounted inside the crankcase, the next step might be to remove and inspect the pump. Open the pump cover and measure clearances. Also, check for scoring or other damage. A broken pump drive would tell you something entered and jammed the pump. If the pump is worn or damaged, replacement is the only option.

    If the pump appears to be okay, the next step would be to measure the rod and main bearing clearances. Check the clearances on the main bearing closest the pump (since this has the greatest effect on pressure), and clearances on the furthest rod bearing (since this will show the greatest wear). If the bearings are worn, they need to be replaced. But before you do so, carefully inspect and measure the crankshaft journals to check for wear, scoring, out-of-round and taper. If the journals need attention, the crank will also have to be reground or replaced.

    Other checks might include camshaft end play, and/or pulling a valve cover or the intake manifold to check the cam bearings and lifters. Remember, excessive clearances or leaks anywhere in the engine's oil supply system can contribute to low oil pressure.

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