All this data logging can drive one nuts. Added to the timing and knock buffer learning curve is this boost issue that has me stumped.

No matter what I do to the boost map I cannot get rid of the 2 dips. This only happens on a 3rd gear pull. It does not happen on a 1st-4th gear acceleration run.

It also shows on the MAS/engine load plot...tubular exhaust manifold harmonic?

Shiv, Dustin, et al would adding a 4300 rpm and 5300 rpm column help get rid of this dip??

 

It looks like you are actually osolating a little bit. Try turning down the boost, and then working your way back up. You should see a flat boost curve, and the curve should continue to stay flat until you get to the point of osolation again.

 

Hi Jorge-- I've seen the same thing before on cars with tubular headers and stock turbos. Very tough to get the boost to not move around a bit in the midrange. Peak boost tends to vary +/- 1psi in the midrange (just after the initial boost spike). Never a problem with cars with stock cast manifold for some reason.

shiv

 

thanks Shiv, Dustin... I gave a try adding 4300 and 5300 rpm points with no change, the wavyness just shifted rpm range. Next try is going to lower boost as Dustin suggests.

All in all I may just ditch the tubular manifold when I add the 10.5 housing next week end.

 

I wouldn't sweat it too much Jorge. Having small boost lumps in the midrange isn't necessarily a bad thing. Probably too small to be felt.

 

Getting brave with the afr?

 

Does anyone else see the engine load vary that much inthe 3500-4000 rpm range?

 

yea, same here.. jumps around in that range.

 

Ok cool