help me understand

[fncrazy]

Ok I know this may not be the right area for this but just really looking for some to take a peek and maybe show mw what I'm doing wrong. I also posted here since I am kind of a noob with dsmlink mas adjustments. Here I have added a log of normal driving and near the end the is a horrifying amount of knock. I do have a wb but it is getting replace and added into the ecus reading very soon. that day it stopped reading( stuck on 20.0 full lean).

Ok let me start with my question now. I would like to understand why in this log there is 40 degrees of time at 3500 rpms just cruising? Also I'm breaking up in the higher rpms but Im starting to address that problem first. Just looking to see if anything I'm doing wrong is standing out? Thanks in advance. BTW no leaks, checked plugs had larger gap like .32. newer wires.

What is being done as we speak new injector plugs, Replace spark plugs gapped to .28, and fuel pump rewire. Which I thought was done already.

Also Im all over dsmlink's wed site watching the videos over and over to help understand, but I'm working with V2 so if you don't have V3 there isn't much help. I will be going V3 in the very near future but want to aleast have a better understanding if this before I upgrade if that makes sense. thanks again in advance!!!

 

[iceguru1114]

While I can't really address all your questions, I can talk about the spark timing. From a high level observable in an ECU, advance is mainly a function of two things: 1) engine speed 2) manifold pressure. I'm neglecting AFR as a variable here, because AFR is also mainly a function of manifold pressure.

Increasing engine speed requires more advance because the heat release rate (how fast combustion occurs) is more or less constant for a given AFR and manifold pressure. This means that you need to start burning sooner in order to achieve peak cylinder pressure at the right time (also known as mean best torque (MBT) ignition timing).

The thing that may be giving you the advance you are seeing, however, is probably more related to the charge air mixture in-cylinder while cruising. When you are cruising, manifold pressure drops, AFR leans out, and the heat release rate drops. When the heat release rate drops, you have to start burning sooner to achieve MBT ignition timing.

Long story short, as long as you're floating around a stoichiometric AFR for cruise conditions and you aren't seeing any knock, that spark timing doesn't sound too outrageous to me.

Hope this helps.

 

[Darksurfr]

I agree with iceguru. The amount of timing you are seeing while cruising isn't outrageous. Under heavy load and boost I would expect to see half of that but there is no reason to be alarmed with 40 without serious load like you are saying.