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Why can't I get my PC to communicate with my ECU? (Back to the top)
- Make sure the ECU is receiving power on the main power leads. These should be connected directly to the battery. Also verify that you have power on the switched +12V input to the ECU (typically a pink wire connected to pin L3 on the main ECU connector). Make sure all wiring harness grounds are properly connected.
- Make sure the communication cable is properly connected between the ECU and the PC.
- Make sure that you have selected the appropriate communications port in the communications setup screen of C-Com WP. Also verify that the communications port you have selected is functional.
- Close all other applications that may interfere with the communications port. Also make sure that only one instance of C-Com WP is running.
- Look in your PC's BIOS setup and verify that the communications port is enabled.
- If you are using a USB to serial port adapter, make sure that the adapter has configured itself for COM1, COM2, COM3, or COM4. Sometimes these adapters will assign themselves to a COM port of 5 or higher. C-Com WP cannot be configured to communicate with a communication port configured higher than COM4.
What is Speed/Density mode or Alpha-N mode? Which one should I use? (Back to the top)
-In Speed/Density mode, the ECU monitors engine RPM, intake manifold
pressure (or vacuum), and intake charge air temperature.
Based on these numbers, along with a user-defined engine displacement
figure, the ECU calculates the volume of air coming into the motor at any given
time. The ECU then calculates the
appropriate amount of fuel needed to operate at the air/fuel ratio specified in
a target air/fuel ratio table. Because all this continually happens
"on the fly", Speed/Density mode provides the highest degree of
tunability over varying weather conditions, altitudes, and engine loads.
- In Alpha-N mode, the manner of operation is much simpler. An injector pulsewidth is simply looked up from a throttle position vs. engine RPM lookup table. The intake air temperature sensor and the MAP sensor are used to measure ambient air temperature and pressure. There is a user-definable correction curve for adding or removing fuel based on air temperature, and a generic barometric compensation curve is applied internally.
-In most applications, Speed/Density mode will provide the best overall performance. Neither mode will produce more power than the other, but Speed/Density will allow for much better drivability tuning than Alpha-N.
-Any turbocharged or supercharged engine MUST use Speed/Density mode.
-You must use Alpha-N mode if you have an individual runner intake manifold. However, it is possible to use speed/density mode with some modifications to the manifold. A small manifold with a vacuum connection to each runner can be created and used to provide a manifold pressure signal to the ECU.
-Alpha-N mode is often used on naturally aspirated racing engines with very long-duration camshafts that produce little or no engine vacuum at an idle. It is sometimes difficult to achieve decent drivability or idle quality with an engine of this type using Speed/Density mode because the amount of pressure in the intake manifold is almost the same at an idle as it is at wide open throttle.
I can get my car to start, but it stalls almost immediately. (Back to the top)
- Make sure that you have correctly entered the appropriate information in the Global Setup Parameters screen and the Fuel Calculation Parameters screen.
- Verify that fuel pressure is correct for your application. Fuel pressure on EFI-equipped vehicles is typically set to 45 psi with the engine off.
- If possible, check the timing with a timing light while the car is actually running. The value seen on the timing light should match the value in a sensor called Spark (BTDC) seen in the Spark table window.
- A common cause of this problem is lack of fuel. Try increasing the numbers in the region of the base fuel table where the engine tries to run after it starts. You may also wish to specify a richer target air/fuel ratio in the Target Air/Fuel Ratio table.
- Look for any values in the main dashboard display (located by pressing the F9 key while online) that would indicate a malfunctioning engine sensor. The TPS value should increase with throttle opening, the MAP sensor should read approximately 100 kPa with the engine off, and the air and coolant temperature sensors should be close to the ambient air temperature, assuming the engine is cold.
I can't get my car to start at all. (Back to the top)
- Verify that an RPM sensor reading is present (usually 100-150 RPM) while cranking the engine. Also verify that the crank reference angle is set correctly for your application, and that the crank sensor timing is set correctly on the engine. Until an RPM signal is present, you won't get any spark or injector pulse.
Note: On GM vehicles using factory ignitions with a bypass feature such as HEI, Buick DIS, or Northstar DIS, the ignition module will generate its own spark during cranking even if an RPM signal is not present on the FAST ECU. If this is the case, you will see spark but will not have an injector pulse.
- If you do see an RPM signal but the engine still won't start, remove a spark plug and verify that you are getting good spark.
- If you are getting good spark, try increasing the pulsewidth values in the cranking fuel table. You may not be injecting enough fuel into the engine during cranking.
- Make sure that you are getting fuel to the rails and that fuel pressure is correctly set. Fuel pressure on EFI-equipped vehicles is typically set to 45 psi with the engine off.
- Verify that each fuel injector is getting a +12V signal on one of the wires, both with the ignition on AND during cranking. The ECU will trigger the other wire on the injector to fire it.
- If the TPS value is at 80 or higher during cranking, the ECU will operate in "clear flood" mode, meaning that it will trigger the ignition but will not fire the injectors.
The car starts and runs, but idles poorly. (Back to the top)
- If the idle is surging, try richening the fuel mixture in the idle area. Surging at idle is most frequently caused by a lean idle mixture. If you are unable to eliminate the surge by adjusting the fuel mixture, try lowering the IAC P and D gain settings.
- Adjust the ignition timing in the spark advance table to see if the car responds favorably to more or less timing.
- If the idle speed is steady but the car idles roughly, try leaning the idle mixture. This will frequently cause the idle speed to increase. Continue to lean the idle mixture until the idle speed stops increasing, but don't make it so lean that the idle begins to surge.
- Most cars idle best at an air/fuel ratio between 13:1 and 14:1. Many factors will affect not only how your engine will idle in this range, but how accurately the oxygen sensor can measure an air/fuel ratio at an idle. Engines with long-duration camshafts and large exhaust pipes tend to produce poor airflow across the oxygen sensor at low RPM, especially if the exhaust system is open. This often results in an artificially lean air/fuel ratio reading. If you have a difficult time getting the air/fuel ratio to read anything other than extremely lean at an idle, you probably shouldn't trust the reading.
- If your MAP sensor reads above 70 kPa at an idle, you may need to use Alpha-N mode instead of Speed/Density mode.
What does an Idle Air Control (IAC) valve do? (Back to the top)
- The purpose of the IAC valve is to allow the ECU to control an additional amount of air to enter the engine without touching the throttle. It's basically an electronically-controlled vacuum leak that allows the ECU to control idle speed. The IAC valve consists of a stepper motor and a pintle. The stepper motor is controlled by the ECU, and the motor moves the pintle towards or away from a seat. The further the pintle is from the seat, the more air is being allowed into the engine. The ECU can raise the idle speed when the engine is cold, or maintain a given idle speed when an AC compressor turns on by allowing more air into the engine.
- To get the IAC motor to work best for you, the blades on the throttle body should be set so that the IAC valve is barely open while idling. This will allow the IAC valve all the room to open up that it will ever need.
- If you are running in Alpha-N mode, use of an IAC motor is not recommended. Because fueling in an Alpha-N calibration is dependent only on throttle position and RPM, the changes in airflow as a result of IAC movement may cause the air/fuel ratio at idle to become erratic, leading to idle instability and low-speed drivability issues.
I'm not sure if my wide-band oxygen sensor is working correctly. How can I tell? (Back to the top)
- The first thing to check is for the appearance of a Lambda symbol (l) in the lower right-hand corner of the screen while online. This indicates that the O2 sensor is connected to the ECU and that the ECU is calibrated for that sensor. The sensor is not properly connected or the ECU is not calibrated for this sensor if this symbol does not appear.
- If the Lambda symbol appears, start the vehicle and look at a sensor called UEGOS (V) in the main dashboard display. This voltage should stabilize between 0.43 and 0.49 volts within 30 seconds of operation. If it does, it is an excellent indicator that the sensor is in good working order. If your sensor seems to be reading incorrectly but the UEGOS voltage is OK, this is most commonly caused by exhaust leaks, dead or misfiring cylinders, or air reversion in the exhaust pipe causing artificially lean readings. Engines with long-duration camshafts and/or large, open exhaust systems often produce artificially lean readings at low RPM.
- If the UEGOS voltage is out of range, the sensor will become inoperative. This could be the result of wiring harness damage, physical damage to the sensor, contamination of the sensor, or damage to the ECU.
-There is a heating element within the sensor that can break if the sensor is dropped or struck by another object. If this element is damaged, the sensor must be replaced. You can check to see if the heating element is broken much like you would check a light bulb - hold it next to your ear and listen for something rattling around inside the sensor. Be certain to hold the sealing washer on the end of the sensor or it too will rattle.
-If the sensor element does not appear to be broken, apply power to the ECU but do not start the car. You should be able to see the element glowing in the end of the sensor within about 30 seconds, and in 1 to 2 minutes, you should feel the body of the sensor getting very warm. You should also be able to look directly into a small hole in the very tip of the sensor and see the orange glow of the heating element.
-Carefully inspect all of the wires leading to the oxygen sensor and make sure that no wires have been melted or pinched. Also pay special attention to the connectors and be certain that all pins in the connector are securely seated within the connector body.
-The sensor element should become a light gray or tan color after a while. If the sensor is blackened by carbon or oil, this indicates an excessively rich fuel mixture and/or oil burning , which tend to dramatically decrease the life expectancy of the sensor.
-If the sensor has been exposed to any significant amount of antifreeze, it is almost certain to fail if it hasn't already. All oxygen sensors are highly prone to damage when exposed to antifreeze.
-Oxygen sensors are also very prone to failure when exposed to salt water vapor in marine applications. The water vapor will dissolve on the sensor element and leave the salt crystals behind, often leading to premature sensor failure.
- To verify that the oxygen sensor circuitry in the ECU is working properly, disconnect the oxygen sensor and observe the following sensors in the main dashboard display while online: UEGO (V) should read approximately 3.51 volts, UEGOS (V) should read approximately 1.02 volts, and UEGOR (V) should read approximately 4.98 volts.
Where should I set my fuel pressure? (Back to the top)
-Fuel injector manufacturers generally rate injectors at approximately 45 psi. It is generally recommended to set base fuel pressure at or very near this setting.
-If your fuel injectors do not flow enough fuel at this pressure, you may be able to increase your fuel pressure to increase the fuel flow capability of the injectors. As a "rule of thumb", every 1-pound increase or decrease in fuel pressure will produce a corresponding 1% increase or decrease in injector flow. If you wish to increase your injector flow capability by raising fuel pressure, be careful! Check with your fuel pump manufacturer to see how changing pressure will effect the volume of fuel the pump can flow. If you are already have the pump flowing at or near what it is capable of flowing, sometimes raising the pressure will actually decrease the flow capability of the pump and worsen the problem!
Can I run methanol with this system? (Back to the top)
-Yes, you can. Methanol generally requires a little bit more than twice the volume of fuel over gasoline at full engine load, so you will need much larger injectors to provide an adequate supply of fuel. DO NOT use any fuel system lubricants or fragrance additives in your fuel when running an EFI-equipped vehicle with methanol. Use of these additives will likely result in clogged or damaged injectors.
-A decent way to approximate injector flow
requirements for a methanol-burning engine is to simply divide flywheel
horsepower by the number of cylinders:
Flywheel HP / # of Cylinders = Injector Flow Rate (lb/hr)
As an example, if you make 800 horsepower with your 8-cylinder engine,
you would need a set of 100 lb/hr injectors to provide enough fuel for this
engine.
-If you are using methanol on a vehicle
being tuned in speed/density mode, you should change the "Injector Flow
Rate" setting in the "Fuel Calculation Parameters" section to
half of the actual injector flow rate. This will cause the ECU to
calculate twice the injector pulsewidth it normally would, thereby doubling the
volume of fuel to the engine. So, if you were using the set of 100 lb/hr
injectors described above, you should enter 50 lb/hr as the injector flow
rate. If you are monitoring fuel consumption in lbs/hr from C-ComWP, the
number shown will be half of what is actually being used by the engine.
If you are tuning in Alpha-N mode, the above information does not apply.
You should enter your actual injector flow rate if this is the case.
-The oxygen sensor will display air/fuel ratios when burning methanol. However, they will be displayed as conventional gasoline air/fuel ratios. This means that the ratio displayed is slightly more than twice as high as the actual ratio; in other words, a displayed air/fuel ratio of 12:1 is, in reality, about 6:1. Also, Lambda values are commonly used when tuning methanol-burning engines. There is a dashboard sensor called "Lambda" in C-Com WP that you can monitor if you are familiar with this measurement standard. Lambda measurements do not vary from one type of fuel to the next.
-It is recommended that the fuel system be flushed with gasoline if you plan on not using the vehicle for more than a week. This will help prevent corrosion problems within the injectors and inside the aluminum fuel rails. Periodic inspection and cleaning of the rails and injectors is also a good idea.
Are there any compatibility problems with certain versions of Windows and C-Com or C-ComWP? (Back to the top)
-We have tested C-ComWP with every version of Windows since Windows 95 and haven't found that any operating system will prevent C-ComWP from working.
-The DOS version of C-Com will not work with Windows 2000 or Windows XP. These operating systems do not support DOS applications.
-It is possible for the DOS version of C-Com to have communication problems when Windows is running on the PC. Because multiple applications can run simultaneously in Windows, other programs running in the background may prevent C-Com from accessing the PC's communications port. If you are unable to communicate with your ECU with C-Com running under Windows, it is advisable to create a DOS boot disk and reboot your PC with this disk in the drive. You can create a boot disk by inserting a floppy disk into your drive, going to a DOS prompt, and typing SYS A: at the prompt. The computer should respond with "System Transferred" after a few seconds. Restart the PC with this disk still in the drive. Windows will not load and you will have an MS-DOS prompt when the PC is finished booting. At this prompt, type the following, pressing the enter key after each line:
C:
CD\C-COM
CC
At this point, if the program runs properly and communicates with your ECU, it is a good indication that a program running in the background within Windows is interfering with C-Com's ability to access the communications port.
My oxygen sensor seems to be working, but my system won't run in closed loop mode. (Back to the top)
-If the oxygen sensor is working properly as per the above information, the ECU will be able to run in closed loop mode. However, there are a few settings within the calibration file that could inhibit closed loop operation from happening.
-Check the closed loop correction limits table. No more correction can be applied in closed loop mode that the corresponding values in this table will allow. If these values are set to zero no closed loop correction can be applied. The net result is the same as running in open loop mode.
-Double-check your settings in the closed loop parameters form. Make sure that the "Closed Loop Enable" check box is checked, and make sure that you have exceeded the coolant temperature in the "Closed Loop Minimum Temp" setting.
-The most common cause of this problem is incorrectly setting the Closed Loop High and Low RPM settings. The engine RPM must exceed the value in the "Closed Loop High RPM" setting before closed loop operation will occur, and it must go below the value in the "Closed Loop Low RPM" setting before turning back off.
-Most current versions of ECU firmware will temporarily suspend negative closed loop correction while the TPS value is increasing. This prevents the closed loop routine from "fighting" the acceleration enrichment fuel that is applied when the throttle is opened. However, this process only happens while the TPS reading is increasing.
-Make sure that no after start enrichment fuel is still being applied. Closed loop operation will be inhibited as long as any after start enrichment fuel is being applied.