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Light Throttle Surge

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  • Light Throttle Surge

    I have the tune dialed in for every day driving on my 460 Ford. Starts, runs, performs great on road. My only issue is when I get in off road crawling situations the throttle control is so touchy it nearly impossible to drive. I’m taking 4-low 1st gear slow speeds when I just touch the throttle it’ll surge and when I let off it’ll nearly die before it catches and the cycle is kind of violent. I suspected timing was jumping around so I tried locking it at 20 with no change. I added a 2 inch open TB spacer thinking I needed the plenum volume and to make sure the MAP was seeing a signal from all 8 cylinders. No change. Lowered fuel pressure down to 34 psi no change. AFRs seem to jump around when the surging/stalling happens so maybe WBO2 sensor? My Target AFRs are 13.5 idle, 14.0 cruise, 12.8 WOT. Timing is controlled 18 idle 34 total 13 vacuum all in at 2800. I haven’t changed PS or PV as I’m going to try that next. Like I said truck runs awesome on the street, but horrible control for slow speed crawling. Any ideas?

  • #2
    I made some changes that seem to help my issue, so I figured I’d post in case it might help some else. After lots of trial & error and lean conditions on throttle transitions, I finally decided to bump up my engine displacement a little at a time and it was an instant improvement. I ended up at 505 CI (started at 460 which is the actual CI). After making this change and liking it, I did have to lower pump squirt down to 15% to not go too rich on throttle inputs. After all this my crawling speed control is 90% better. Not perfect, but good and my street performance is still spot on. Hope this might help someone.


    • #3
      To close this one out, lowering the PS % solved my issue. The truck is still touchy when crawling, but it is definitely driveable now.