SenX Frequently Asked Questions
Q.1 What specs are required for my oscilloscope? I don’t want to buy another one if my current one will work.
A: Please refer to the “What do I need?” section on the web because the answer depends on what you want to use the FirstLook sensors for. Most important are:
How many channels will you need? (How many sensors, including trigger, when appropriate will you be needing?)
How high of frequencies will you want to accurately detect? A 4-stroke engine running at 1500 rpm has piston / valve events at about 80 Hz. Valve ‘leakages’ whistle at around 8,000 Hz. If you use more than one simultaneous sensor, multiply your needed frequency by that number.
If you want to store and programmatically analyze the signatures, you want software that provides such analysis or can store and export the results for later reference.
Q.2 What specs are required for my current PC to work satisfactorily? Will an Apple work?
A: You should check with your PC oscilloscope distributor. If you are using a hand held oscilloscope, the device should be plenty powerful for automotive cycles.
Q.3 My oscilloscope is showing twice as many ‘humps’ as I would expect given the RPM table. What is going on?
A: Such phenomena are usually a result of reflections (echoes) in the tailpipe or related components. Consider neighboring ‘humps’ as a group. Use the downloadable Timing chart to get the interval for each cylinder as a means to identify the appropriate group of humps.
Q.4 Is there a minimum mileage a vehicle should reach before testing?
A: No. To evaluate your engine, it is smart to test it every time you get an oil change. This enables you to anticipate problems rather than just react to failures out on the road.
Q.5 Are there vehicles that should not be tested? (e.g., diesel and turbo applications)
A: The tool was designed, engineered and tested on gasoline and diesel engines with 3 through 8 cylinders. Turbochargers, catalytic converters, mufflers, and tailpipe geometries might affect pulse shapes by reflections whenever there is a curve or change in diameter of the tailpipe. But they do not affect the (ir)regularity of the patterns.
Q.6 If we test a vehicle twice (back-to-back), without performing a service, will the reading be the same?
A: Yes. But every engine produces slight variations, which the sensor detects. In our documentation and procedures, we focus on physical integrity which typically doesn’t produce intermittent, significant variation. We are primarily looking for irregularities that return every 4-stroke cycle.
Q.7 Does it matter if the engine is hot or cold?
A: Yes. A cold engine may produce false results, especially in diesel engines. Before an engine can be tested, it should be up to normal operating temperature. Cold engines might give ‘false positives suggesting problems that disappear upon warming up.
Q.8 Is there any correlation between number of cylinders and test results? (e.g., does a 4-cylinder vehicle typically test better than a 6 or an 8?)
Q.9 Does type of fuel used play a part in the test results?
A: Yes. It’s important to note that many factors can impact an engine’s performance. Engine type, age and maintenance history; individual driving style, fuel quality as well as environmental factors. Poor engine fuel quality typically exhibits itself with intermittent ‘problems’.
Q.10 How to care for your SenX sensors.
A: Keep water out of the sensors by storing them with the threaded side down. Don’t pull the threaded sensors from hoses, screw them out. Use the nipple adapters to insert into hoses when possible. Use appropriate oil tube attachments to get a good, tight fit. You might have to try several different ones to get a snug fit.
Q.11 Additional Exhaust and Crankcase sample collection considerations:
1. Some oil dipstick tube tops are difficult to get at: Some smaller engines (Yanmar, etc.) have 1.25” ID oil fill/dipstock tubes. We provide a 1.25” OD plastic tube with 1” ID for the 3-way adapter in the kit.
2. To get a sample from a common Cummins dipstick tube with the notched ‘cup’ at the top, we provide a clear plastic attachment so that the narrow section can be inserted into the tube and the SenX sensor can be inserted into the wider diameter tube. The narrow tube fits many oil dipstick tubes snuggly.
3. Some horizontal exhausts now have baffles to reduce the danger of starting grass fires from the heat of DPF regens. To accommodate these, we provide a 27” silicone rubber hose that can be used to ‘thread’ through the baffles to get a good exhaust pulse from the exhaust. The SenX sensor with tapered attachment can be inserted to the external end of the hose.
4. The clamp of the provided exhaust sampler might slide and squeeze the silicone hose. Verify that the clamp is over the metal insert that is designed to prevent distortion of the airflow from the exhaust to the sensor.