Will retarding timing reduce NOx?
The results indicated that by retarding spark time 10 from MBT with 30% of hydrogen increased thermal efficiency and natural gas emission while decreased NOx emission compared with engine work on natural gas. Ignition timing is heavily related to flame speed, which has great effect on SI engines performance.
What causes high NOx readings?
Advanced timing or a poorly functioning cooling system can push combustion temperature high enough to affect NOx levels. If your car is equipped with an EGR valve, it should be checked for proper operation and possible carbon-clogged passages.
Why did NOx fail?
engines failing NOx caused by lean condition. General Motors Multiport Fuel Injection engines may fail emissions standard testing due to excess Oxides of Nitrogen levels in the exhaust gas. Here are some steps to determine and correct the cause of high NOx emissions.
Can a bad catalytic converter cause high NOx?
A vehicle’s catalytic converter helps remove NOx from the exhaust before it gets to the tailpipe by passing the gases through a titanium oxide membrane. A defective catalytic converter can then result in elevated NOx emissions.
What is a typical acceptable NOx value?
between 50 and 1000 ppm
Concentrations of NOx in untreated diesel exhaust are typically between 50 and 1000 ppm. If concentrations are given in mass units, NOx is usually expressed as NO2 equivalent.
How do you fix NOx emissions?
The solution to this problem is called De-Carbonizing. It usually costs around two labor hours at a smog check repair station. It will remove a good amount of carbon out of an engine. This will increase combustion space, lower compression and lower NOx.
Can a timing adjustment be used to lower NOx?
Should it be off spec and the test fails, an adjustment is sold and performed, and the vehicle is retested. It appears the test failure was for excessive NOx only, so it seems the tech might have adjusted timing below specs (more than a couple of degrees is a test violation and ill advised from a performance standpoint).
Is there any way to lower engine NOx?
Timing Adjustment Can Lower Nox. Proper ignition timing – a combination of the base setting and advance system – is critical for optimum performance, fuel economy and low emissions. An engine with excessively advanced timing will run well, but is prone to ping (harmful abnormal combustion) and produce excessive NOx.
Why is the timing not set to 5 degrees BTDC?
– Given that the mechanic adjusted the timing to bring the timing into compliance and pass the smog test, why would the timing not be set to the specified 5 degrees BTDC? Looks like spaces in our messages get removed, so posting formatted tables is difficult. Here is a reformatted version of the test results.
What causes a car to have an elevated NOx?
Timing Adjustment Can Lower Nox. Common causes of elevated NOx are a lean air-fuel mixture; advanced ignition timing; lower than specified octane fuel; a faulty EGR (exhaust gas recirculation) system, if used; carbon buildup in the combustion chambers; elevated engine temperature and a weak catalytic converter.