Diesel Place banner
1 - 1 of 1 Posts

·
Registered
Joined
·
55 Posts
The link below imparts an good education on the noise you describe; posted by "modified" on 10-26-03.


Topic: sound changes at 2800 rpms



<TABLE cellSpacing=1 cellPadding=3 width="100%">
<T>
<TR>
<TD class=bold width="20%" background="" bgColor=#f8f7ef><A name=15153></A>modified</TD>
<TD class=smText width="80%" background="" bgColor=#f8f7ef>
<TABLE cellSpacing=0 cellPadding=0 width="100%">
<T>
<TR>
<TD class=smText noWrap>Posted: October 26 2003 at 7:09pm </TD></TR></T></TABLE></TD></TR></T></TABLE>
Here’s a description of Pilot Injection, copied from Overdrive Lockout Info at :

http://dieselplace.com/forum/forum_posts.asp?TID=754&PN=1



Diesel engine fuel injection systems that use a common rail system, as the Duramax™ diesel does, may or may not have what is referred to as pilot fuel injection at the lower engine speeds. Pilot fuel injection is defined as a pre-injection of a small quantity of fuel 5 to 20 crankshaft degrees before the main fuel injection. This pre-injection softens the main injection pressure rise and reduces combustion noise. At engine speeds above 2600 RPM, and a fuel quantity supply greater than 35 cu mm, it is necessary to eliminate pilot injection to meet emission requirements. When driving at or above these speeds, main injection combustion noise may be noticeable. It is normal and not harmful to the engine.


When traveling in 5th gear, the pilot injection to main injection transition is typically in the 136 km/h (85 mph) range, however it may also be heard under heavy acceleration and when pulling loads up a hill during shifts at or above 2600 RPM. Customers that install the fifth gear inhibit switch may encounter the fuel knocking of main fuel injection at speeds around 107 km/h (67 mph) in fourth gear between 2600 and 2700 RPM. This sound is considered normal and is to be expected.


http://www.dieselplace.com/forum/forum_posts.asp?TID=1614&KW=pilot+fuel
 
1 - 1 of 1 Posts
Top