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Thread: 1998 Chevy Blazer 4.3 with cam, tuning help

  1. #1
    Potential Tuner
    Join Date
    Sep 2021

    Question 1998 Chevy Blazer 4.3 with cam, tuning help

    Hello! So I'm plenty familiar with tuning carb'd engines but with this fuel injected stuff I'm a bit lost.

    I needed to replace the intake gaskets on my 1998 Blazer with the 4.3 so I pulled the thing out and replaced all the gaskets. But because I'm an idiot, I said, "hey, why not a cam?" So in went the Comp 260/266. Which also meant I had to change rockers, so it got 1.6:1. Also some shorty headers just for giggles.

    So now it's running way lean according to the spark plugs and has a light load misfire when warmed up. Scanner shows the fuel trims around 20% if I'm remembering correctly from the last time I looked at it.

    I have an MPVI2 now, where would be a good place to start dialing this thing in?

  2. #2
    Advanced Tuner
    Join Date
    Sep 2009
    Disable the MAF sensor and start dialing in the VE table. Remember the black box only uses the secondary table when the MAF is disabled. Then turn the MAF sensor back on and tweak the MAF table.

  3. #3
    Tuner in Training Dynamic's Avatar
    Join Date
    Mar 2015
    I'm doing a 2003 S-10 P/U with a 4.3 as well. The long term plan is to LS swap it, but in the interim, I'm doing a custom grind cam and a set of long tube headers on the 4.3. I'll be following your progress.

    What valve springs and retainers did you use with your cam?
    2004 Dodge Durango, 5.7L Hemi, 10:1 compression
    -SRT8 cam, advanced 6 degrees, 6.1L valve springs
    -Manley pushrods
    -Scat rods, Speed Pro pistons

    2004 Dodge Durango, 392 Stroker, 11:1 compression
    -Custom cam grind, 221/230, .575"/.585", 115 LSA, 3 degrees advanced)
    -Scat forged 4.05" crank, Scat Ultra Q-Lite H-beams, Mahle forged pistons
    -Stock heads with 6.1L valves (2.08", 1.60"), bowl work to match new seat profiles
    -PSI LS1511 valve springs