sup everyone. just wondering if you guys think my boost curve looks normal.

GREEN is AFR
BLUE is RPM
WHITE is BOOST






i always get this boost dip starting ~4200rpm to about ~4800rpm. sometimes it is a little worse than that, sometimes not.

i've been told that it can be 'tuned out' but i don't think it's the tune. i was thinking that maybe it was my mbc (dejon tool). i've looked at logs from a long time ago when i had my mbc+other mods installed and i've always had this boost dip. i guess i didn't really notice until i started tuning. when the boost dips, my AFR spikes a little bit. you can see it in the curve, which is why i had to richen that area so it wouldn't spike so high.

the only other things installed at the same time as my MBC was my TBE, injectors, fuel pump.

anyway, anyone think it's my mbc or anything else? i'd appreciate your ideas. thanks!

 

My Uk (jdm spec) 8mr does exactly the same thing using the standard boost control, so would be interested to see peoples views on this.
I haven't tried to tune it out yet as only noticed it the other day.

 

its prolly a resonance point. it appears to be pretty small and for a brief amount of time, so i wouldn't worry about it.

 

Yeah, isnt the dip only like .5 psi.

When I use my ZT2, i like to put all the plots on the first graph. It make for more resolution in the lines.

 

thanks for the replies so far, guys.

evo_kid, it's actually more like 1-1.5psi. if it were .5, i don't think i'd be worried about it as much. i mean, it's enough of a dip to make my AFR go lean in that area. u can see how i had to richen the area to keep the spike down. my 4000+ fuel map cells should actually be about a point or two leaner.

also, all plots as in you log everything? i log everything except User1 and Lambda.

 

No I log RPM, Boost, AFR & TPS. I was saying you can put all the lines on one graph. When you do that everything is bigger and you can see dips and spikes better.

 

oh i see what you're saying. yeah i rarely view my logs like that.

 

Just a shot in the dark but a brief missfire would cause a little A:F spike and the resultant lapse of combustion would likewise cause a dip in boost at the same point.

This is happening just slightly after peak however.

What psi is that at?

 

20-21psi. running ngk br7es @ 0.026. i had brp7es before these.

i just bought bpr8es today and was going to install them.

 

you may be hitting over the boost desired load point (boost desired load + boost control load offset)) and the ecu is pulling the boost back down to correct for it.

 

He's using a MBC, not the stock ebc.