I have aquired a bad misfire at low rpm and random missfire through out the rpm range. This happened after changing out header gaskets, I checked the plugs and wires and they are fine, so I must of messed up something else in that area.


http://www.ls1lt1.com/forum/attachme...6&d=1155686284

The missfire on the WOT run was the worse I have had.

 

this is funny to me. i changed my driver side header gasket today. no leaks now. and the miss at WOT i was having is now throughout the rpm's.
if u are having the same problems as me. walk outside tonight, start the car and pop the hood. see if you wires are arcing.

 

Just did that, and didn't notice any arcing...but I burned the **** out of my hand when I touched my ceramic intake elbow....it shouldn't be that hot after sitting for 3 hours should it?

 

well that is the only recommending i could do for ya, as that was my problem. i hope.
also everything in my engine bay is hot to the touch for hours. after 8 hours the intake manifold is still warm.
hope you find out the problem is soon. GL

 

Anyone have any ideas?

 

If you want those of use who do not have DataMaster to look at the files, you have to post them in ".csv" format, not the DataMaster ".uni" format. That way it can be opened with Excel, which makes it a lot easier to manipulate and analyze the data.

There is an "export as .csv" option (or something like that) in DataMaster. Make sure you export the entire file, because a common mistake is to export only the first record.

 

Sorry, didn't know.

When I get home I will do that for you guys.

 

Its close to impossible to see a misfire in a datalog during random driving. The only real data that will show a misfire is the WOT run. And in that run you can see the left bank go lean a couple of times... so my guess is you have a bad plug or wire on the left bank.

 

Notice the 10.9 degrees of spark retard?

Left would make sense, that's the side I did the header gasket on...but I jsut don't see anythign wrong.

 

Spark retard tells me nothing. You said there was a misfire... spark retard has nothing to do with that IMO. What you need to look for is a lean spot in the O2 sensor readings. That will indicate a cylinder dropped which sent unburnt oxygen to the O2 senser... sensor reads lean for that instant. If you pay attention you can catch it a couple of times around 4000 rpm. My guess is you cut a wire or cracked a plug.

 

That's mine as well, wires and plugs look fine..but I'm changing them out tomorrow anyway.