The reason it’s important to know how a WBOS works is because there are several conditions that can fool an oxygen sensor into thinking that the engine is running lean.
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An air-fuel ratio of 12:1 for example would be considered an excess-fuel ratio and contain very little free oxygen because there is more fuel available to use more air to combust the fuel. With lean air-fuel ratios such as 15.8:1, there is more free oxygen in the exhaust because there is minimal fuel to complete combustion. The ideally-balanced chemical air and fuel ratio for any fuel is called the stoichiometric ratio. Instead, they are calibrated to sense the amount of free oxygen in the exhaust system. They do not actually measure the ratio of air to fuel. As their name implies, these wide-band sensors (WBOS) operate over a much wider area of air-fuel ratio from very rich at 10:1 to very lean at 20:1. The sensor reads the exhaust gas and the engine control unit – the computer (ECU) uses the information as feedback to the tune. Unfortunately, this can cause problems with a self-learning EFI system.Īll of the self-adapting EFI systems use a wide-band oxygen sensorplaced roughly at the header collector, downstream in the exhaust system. Think of it like a siphon pulling fresh air in from the outside. This low-pressure spike will pull in outside air as it passes through the leak area. When that pressure spike hits the atmosphere, it sends a reverse or low-pressure pulse back up the pipe and back to the engine. The tick you hear is the result of an exhaust pressure spike that travels down the exhaust pipe, finally exiting after the muffler. If you’ve ever driven a car with an exhaust leak, you can often hear a very audible tick-tick-tick from the exhaust. If the over-rich condition returns, I think what you may be experiencing is a very common problem where there is a leak in the exhaust system that is causing the over-rich air-fuel ratio problem. You may notice that the engine begins to run rich again after several cycles of running and then shutting the engine off. Drive the car for a couple of days and make sure to shut the engine off and restart it several times during the test. Once all this is complete, the engine should run as it did when you first installed the system. Then set your idle, cruise, and WOT settings the same as before. This means starting with engine displacement, idle rpm, rev limit, fuel pressure, and resetting the throttle position sensor (TPS) calibration. This essentially purges the computer’s memory of the previous tuning changes. The next item to try is to run back through the initial calibration process again. Don’t be afraid to lengthen either or both power and ground leads if that what it takes to plumb them directly to the battery. This allows the battery also to operate like a giant voltage spike suppressor which allows the electronic side of the system to operate normally. So it is essential that the main power and ground leads go directly to the battery. This leaves very little room for error with regard to proper grounds. All EFI systemsoperate on electrical signals from sensors that normally operate on a 0-5-volt scale. The first thing to emphasize is that the main power and ground wires are in fact connected directly to the battery. Let’s see if we can focus in on your problem.
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But there are a couple of areas where it is essential that the initial installation be performed properly and then attention to details can make all the difference. Jeff Smith: We’ve installed several of these new-generation, self-learning fuel injection systems and they seem to work very well. Attending to the details will make a big difference in how the system works.
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The rivets will need to be drilled and the metal portion removed to be attached to the corresponding application.This is an EZ-EFI throttle body on a big-block Chevy we did a couple of years ago that worked out very well. The Olds and Pontiac fiberglass portion of the unit are the same. (See pictures to identify) The bottom portion of the shaker unit is metal and is riveted to the fiberglass shaker. To use a shaker scoop from an Oldsmobile engine you will need to locate another shaker from a Pontiac application. Shaker ring may need to be inverted to due to rounded lip on the base 90 degree or banjo fitting may also be neededįor some XP carbs the radius inside the drop base may need to be "massaged" to clear the float bowl Modification of the drop base may be necessary at the fuel inlet fitting. Can be used with EFI Systems- FAST EZ 1.0, 2.0, Holley Sniper, FiTech are all carb height which is close to 3.225".