S10 4.3 Vortec ZR2 Stumble / Hesitates Just After Taking Off

I have a 99 S10 that I just bought a few weeks ago. My wife was hesitant letting me get a new toy, but caved as long as it was a good deal and didn’t have to put much money into it. I love this truck, can’t believe I almost looked at a Ford. Got the 4WD working great now, and a tranfer case leak taken care of, but still hesitating.

Starts great, but if you drive away right away, it stumbles in that first block or two, then it acts like you flipped a switch and runs great from then on. Does this every single time after starting it, so I can’t start and dart into traffic or I get “the looks” for people. I found that if I just start it and let it idle for a minute or two before going, then it seems to be better.

I’m not getting any DTC codes. I don’t have a fuel pressure gauge, and really don’t want to do parts shotgun replacement. The way it seems to click in and then go fine seems like a give away, just not giving it away to me.

Any thoughts from anyone?

3 thoughts on “S10 4.3 Vortec ZR2 Stumble / Hesitates Just After Taking Off”

  1. hi,i read somewhere it could be due to the cmfi/csefi unit at top of engine.it is activated by the pcm wich is served by severals sensors,get hold of chiltons repair handbook for s10,you can read all about it.have the same problem some times after washing my ยด00 s10 4wd/ peter

  2. About 3 wks ago, I noticed my 02 ZR2 looked “off” in the rearend. I asked a few people, nobody seemed to notice anything, figured maybe uneven parking lot, angle, etc. Or maybe it’s just in my head? I ended up measuring from the ground to the bottom of the fender flare, just above the wheel well and VIOLA!…it was 1 3/4 in lower on the right side. (I wasn’t crazy! Merely neurotic!)

    I called my trusty uncle, who owns a tranny shop but seems to fix almost anything. I totally trust him. He put it on a rack, checked springs, struts, shocks, etc. Almost 2 hrs later, he tells me he can’t find anything & has me take it to his alignment/suspension guy down the street.

    Tire guy racks it, gauges it….does his best to figure it out, but can’t pinpoint the stoop. My uncle said truck seems fine, but if it’s bothering me, take it to his bodyshop guy. I ran into a different bodyshop guy, and less reputable, asked him about it. (he’s done work for my parent’s…wouldn’t let him touch my truck!) He says torsion (sp?) bars need adjusting. I asked if that’d lift the rear corner up, he said yes. Uncle said “uh uh”…bad info.

    So, basically I’m wondering if you’ve ever heard of this, and what might be causing it. The truck drives straight as an arrow, doors & windows have always been fine…seal perfectly. No rattles or other sounds from rearend at all…either side. I’d asked the tire guy if he’d seen evidence of it having been wrecked & repaired underneath. He said “no”…and that’d he’d looked for any. 2 reputable car shops…everyone’s still stumped. Should I take it to the trusty “bodyshop guy”? Live with it??

    Thank you so much for any help/insight you can give me!! Take care

  3. My guess is either the fuel filter which you would expect it to happen all of the time or more likely the Mass Air Flow Sensor, it’s the electronic device on the air intake to the engine, hard to miss. I had the almost exact same thing happen to my 99 LT and I replaced that and it squealed tires all the way down the road immediately after.

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