[Gmecm] 7747 stumbling acceleration when cold

[Scott Peitzsch]

Even with your caveat below, I'd suspect this is directly related to the lack of a
properly functioning Thermac system.  Without a well regulated source of warm
air, basically every 7747 I've ever tuned with an open air cleaner exhibits the
symptoms you describe below.

I'd suggest either returning to a stock style air cleaner and intake with a fully
functional Thermac system, or consider switching over to a 1228746 ECM.  The
8746 is pin-for-pin compatible with the 7747, and adds IAT capability, which
should go a long way towards solving your issue.  I've used this solution with
excellent success on a few recent trucks I've tuned.

-Scott

  ----- Original Message ----- 
  From: Charles McDowell 
  To: gmecm 
  Sent: Sunday, November 28, 2010 12:09 AM
  Subject: [Gmecm] 7747 stumbling acceleration when cold


  I'm hoping someone can point me in the right direction of what to change in my BIN to solve a bad cold acceleration issue with a 7747 TBI.  The truck runs great once warmed up, but when the engine is still warming up (and worse on colder days) it stumbles through it's acceleration, sometimes even backfiring.  It sort of comes off the line decently, then bogs down and gradually works its way up to speed.  Any pointers on what I might change to fix this?

  Not sure if it matters, but this vehicle has an open air cleaner and no heat riser stuff.  I don't think that should be the issue since this happens even when it's 55 degrees out, but I thought I'd mention it in case.  Thanks. 


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