Boost reading issue

S10 Guy

S10 Guy

Member
Long story short, i have had two different mechanical boost gauges that both read up to 14-15 at WOT. Yesterday forum member Blue83z (Matt) was generous enough to let me borrow his Scanmaster 3 (chassing down a cutting out / possible overboost issue at WOT)

The screen on his scanmaster had one little gremlin of the last digit far right of screen was acting up but all the settings seemed to be showing good values. first WOT run the scanmaster showed a boost reading of 24 psi, and kept showing readings around the 20 psi mark. Whilst at the same time my mechanical boost gauge was only showing 10-14 psi. I only performed a visual check over and didnt see anything wrong.
maybe possible bad MAP senor??
Sorry, kinda long story lol.

I am running a Forge Wastegate, Stock injectors, fresh SM's tune-up, new Aeromotive 340 pump, new fuel filter, and new SM's AFPR. Been having the same issue with my stock chip and my ATR chip.
 
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blue83z

Donating Member
Re: Boost reading issue

I never changed any settings from my (stock) truck to his.

I assumed it just read what the ECM was doing, no matter what the map sensor, just like a tech 2 or Otc type scanner would. Is that incorrect?
 
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Eric Sy GN

Donating Member
Re: Boost reading issue

There is a setting in the Scanmaster to tell it whether you are using a 2-bar or 3-bar map sensor. (see Scanmaster instructions) Make sure it's set correctly for whichever map sensor you are using.

A Tech 2 or OTC will not read the right boost or map reading with a 3-bar map.

Eric
 
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blue83z

Donating Member
Re: Boost reading issue

just remembered, your truck has stock 2 bar map like mine does, so the assumption would be that I had it correct in mine and its correct in yours.

question would be then......since the mechanical gauge read 15 psi from the vacuum port on the manifold, and the scanmaster read over 20 psi, why the difference?
 
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