With gas prices steadily climbing I've been tweaking My Blazer with the goal of optimizing fuel economy . I was running a set of premium NAPA 8mm wires , a recently installed set of OEM spec delco plugs , cap and rotor with very good results - smooth idle , peppy throttle response and engine timing right at 0 degrees . Gas mileage not that great though ...
No codes or check engine light and easy engine starts , hot or cold .
So I'm at the local pick-n-pull or ******-n-grab junk yard and happen upon a row of (engine component wise) intact 4.3 equipped Jimmys and Blazers so I went to town pulling every sensor and engine control device , wires and parts . I got home and swapped out the
(premium) napa beldon 8mm wires for a near new set of AC Delco 7mm spark plug wires pulled at the yard - go to start the engine and just a bump of the key fires the motor up now . NICE ! Next I swap out the (as far as I know) factory installed MAP sensor with one pulled from the J/Y and go for a test drive ... now I have way better braking and overall drive-ability such as transmission shift points depend on how much throttle I'm giving it . I mean the thing chirps second gear now without even having to get on it much as I found out tonight on a test run - felt like a kid again circling the block
I did find that at least this 4.3 engine seems to run a lot better on the mid grade 89 octane compared to the regular I was running . I get more miles out of a tank in this '95 two door two wheel drive ... I like it .For what I need - She's a keeper

 

It would be interesting to see what each of those maps read out on a scantool.
And how they track from atmosphere (engine off) to warm idle against an accurate vacuum gauge

Cannot understand how any of those would affect braking

 

appreciate the response

I can only speculate that the more accurate MAP sensor responds faster to engine intake vacuum and load conditions ? For instance , when approaching a traffic light or stop sign previously the brake pedal was "harder" to push down , right after taking your foot off the accelerator to apply brakes. Engine idle RPM's are similar , 650-700 warmed up . Around 850 to 950 cold at startup then dropping ...