[Gmecm] 305 TBI Hesitation

[Steve Ravet]

> 
> THis one has plagued me for a year now and like a man it is 
> finally time to ask for help.
> The Project:
> 305 CID Small block TBI  7747.
> I'M  trying to figure out two things still. I have a high 
> idle problem that cannot be lowered by altering convention 
> cell settings for the idle. Something in another area is 
> holding the idle up to 1100 RPM no matter what is done, it is 
> not mechanical. The computer wants to increase the idle in 
> gear at a stop sign.
> This might be related as well .If the throttle is opened up 
> slowly under load, the engine hesitates or stumbles as though 
> it is going lean. If you let off the throttle ( around 1100 
> RPM ), it hesitates and
> the engine surges back as though it went suddenly went rich.   Now if
> you step on it Hard, the engine jumps with all kinds of power 
> and runs as it should. My question is has any run into this 
> before and which cells are responsible or maybe over riding 
> the others? I need some more heads on this one....Fred

I had a similar problem some time ago, you can search in the archives
for "creepy idle".  With a scan tool I could see the "desired idle rpm"
creeping up while stopped and in gear.  From a fully warmed up desired
RPM of 550 it would slowly creep up to 800 or so, opening the IAC to 180
or more in the process.  I got used to shifting to neutral when coming
to a stop.  While looking into it I discovered that a wiring error meant
that my P/N switch had never been connected correctly.  It was always
indicating in gear.  (This is a swap project, 350 TBI into an S-10
Blazer, I've been driving it for 9 years now).

Fixing that, however, did not solve the problem.  Unfortunately I don't
know what did solve it, as it just gradually quit doing it.  I checked
CTS, VSS, etc. on the scan tool and all were correct.  There were some
other suggestions in response to my original post that I never got
around to trying, you might try to dig them up.

--steve


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