[Gmecm] '7730 Stumbles at cruise

[DV Fagan]

Cowen,
Check your IAC passages for carbon or gunk.  Check
your TPS for proper values.
Dennis
--- Cowen <captain_krill at yahoo.com> wrote:

> Hello folks,
> 
> It has indeed been quiet, so here's a question to
> generate some discussion.
> 
> I've got a stock '730 ECM from a 3.1 running, a 3.4,
> with injection parts from a Fiero 2.8, with DIS. 
> This setup has been going almost flawlessly for
> about 2 1/2 years now, and I love the power,
> mileage, low emissions, and year-round easy starting
> compared to the carb it replaced.
> 
> Unfortunately, it has picked up two small issues in
> the last 6 months or so.  First, it stumbles a bit
> at very light cruise. I have no VSS yet, so I'm
> pulling a code for that, but nothing else.  I have
> the (digital) EGR vacuum plugged too, but I don't
> think it enables without VSS anyway.
> 
> Secondly, when the engine is cold, the there's a bog
> coming off idle unless it's revved up.  This feels
> like the IAC is closing in response to throttle
> input.  I had this problem when I first got things
> going, because the throttle plate was adjusted for a
> 2.8 and the IAC had to overcompensate for the air in
> a 3.4, so properly adjusting the throttle body
> completely cured it, until now.  I've tried
> increasing the throttle at idle slightly (reducing
> IAC counts required), but it hasn't affected the
> mild bog.
> 
> I know my setup isn't perfect with no VSS (I'll be
> transplanting the whole shebang again into an MGA
> next year anyway), but the thing is it didn't have
> this stumble for more than a year of operation. 
> I've done a quick check for loose connections at the
> TPS and IAC and they look good.  I can't find any
> vacuum leaks and it still runs wonderfully
> otherwise.  
> 
> Any suggestions on what I should focus on?
> 
> Thanks!
> 
> 
>        
>
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