I have a 98 blazer with 50 k on new Jasper engine, and 180 k on everything else. It runs strong , idles good. But everytime I start it when cold, the exhaust pop's coming from tailpipe. It only pops at the exact moment it actually starts, and after its warmed up to normal operating temp it doesn't do it. What could this possible be spark plugs, fuel pump, sensor ?

 

Has the engine thrown any codes?

 

What do you mean by "pops"? Is it only one pop? Anyway you could shoot a video and pop it up on Youtube or Photobucket?

 

No it doesn't throw any codes. The pop is coming from the rear tailpipe. It only does it worse when starting engine in the morning, or after its been sitting. After it warms up to normal operating temp. it doesn't do it all of the time, it will start up like it should more often than not. It only pops when starting, never while driving. The pop isn't very loud, but very noticeable( I get a lot of looks ). It is a single pop, like a 1/4 of a backfire i guess ? It pops right at the moment before the engine starts. Like i said it is a single pop, not like traditional backfire. So its not a WaaaPaaaw , more like a POOP .

 

When you shut it down does it immediatly quit? Might be a little fuel left in the exhaust does it sound like a racecar when they go into a corner? that little pop?