Running the EBL flash on my 89 IROC. Does the EBL measure in Kpa in the "vac" column of datalogs? I presume it does but wanted to confirm.
I have what may be a TB sizing issue. During WOT datalogs the vac drops to "0" as you would expect but as it passes the torque peak (~4000) the vac starts to climb and gets in the 6-8 range at around 5700. At first I was thinking it was in/hg and thought wow that's a lot of vacuum. But it's most likely kpa and that equals around 2-3 in/hg. Still probably enough to warrant a TB upsizing. Especially since I
I'm running a stock TB on a 414CI motor!

 

The vacuum reading is in KPa. The ECM calculates it by subtracting the current MAP reading from the current barometric value.

RBob.

 

Thanks Bob. Do you think 6-8kpa vac on datalogs indicates restrictions on the intake such as throttle body or filters?

 

An 8 KPa drop is 2.4" Hg (vacuum), which isn't too bad for a street car. But can be better. Do some testing to see where the most drop is.

RBob.

 

Vac is 0 @ 3k and steady climbs to 6-8 @ 5700. Power seems to be tapering off at that rpm. Is there any specific tests you recommend? My plan is to make a pull with the air filter Y duct removed to see if it changes. Although it will be ingesting hotter air i figure it should still give an indication of the air duct restriction. If the vac is the same it would indicate the TB is a restriction. If it changes I'll see what i can do about the filter setup.