thats very interesting, and would explain why a certain persons ROM I saw recently had 8* at peak torque, BUT also had 50*+ of cam overlap at peak torque as well... I wonder if this affect is allowing them to run 8*

hrmm very interesting! i like this theory hehe

so basically if the HFC has cleared the exhaust restriction then iEGR is no longer taking affect, so my cylinder temps have gone up, and thus my knock resistance has gone down.

so to fix, either:
1) reduce timing
2) retard exhaust CAM MORE, so that more exhaust can enter.

but really iEGR is NOT what you want, so number 2 is OUT, so reducing timing is the better thing todo..

edit - i would have thought that HOT exhaust gases being injected back to the cylinder would have made the mixture more pre-ignition prone?

 

and I should be able to prove this theory by reducing the retard on my exhaust CAM. to simulate a clearer exhaust?

 

Yes reduction of the exhaust retard

 

Tephra, have you tested with less exhaust retard yet?

 

Add New Item

Enter in these parameters... Presto...

 

I retarded the exhaust cam slightly, but it didn't really do much...

I did about 6 pulls today and no knock, i have been leaning out the map to 11.7 as well..

so yeah i'll do some more testing then put the cat back in...

bizzare!

 

So, its almost back to normal now? What changes were made since it started knocking?

 

seems that way...

well i have added 1/4 point of fuel in the 3000rpm column, during spool mainly.

but leaned out the rest of the map a bit...

i will get a new decent log and post it up tommorow...

i dunno, i prefer to have a proper resolution to the problem

 

So spool-up is a little richer now. I can understand wanting a proper resolution as most of us should. I'm still worried about the exhaust mivec being so slow.

 

have you logged your car for MIVEC?

 

I haven't had a chance to run out and log the car, but I will shortly.

 

maybe we should make a new thread, about MIVEC lag, and get some results from different mods (like stock vs exhaust vs oils etc) to see if there is a pattern?

 

quick question - my brain isn't working today:

if I reduce my exhaust cam retard and my AFR leans out, what does that mean?

can the only conclusion be that I have achieved a greater VE? or is there any other explaination?

 

Something intersting here from my car...

Notice the correlation between target and acutal... MIVEC overshoots the targert...

Causes very lean AFR's, then once MIVEC is stable again AFR's return to normal... or specific values...







I been messing with MIVEC, so the target AFR's are a bit more from the orginal map I had setup. Either way to me it seems that each time MIVEC overshoots the target values the AFR's lean out...

 

You are making more power.I noticed the same on dyno at high rpm.