[Gmecm] Re: +AFs-Gmecm+AF0- 305 TBI Hesitation

[David Allen]

  Does your calibration have a table that modifies idle speed vs. battery 
voltage?  Could there be parameters in the calbration which are not called 
out in the definition file?  I caught heck with a project this year having a 
similar problem.  It would idle very high and according to scan data the ECM 
was calling for this idle- just like in your case.
  My calibration had a table for desired idle speed vs. battery voltage. 
There is something wrong with the calibation or the definition file because 
the ECM only responds to the LOWEST battery voltage range in this table. 
Even though the ECM reports a battery voltage of 14 with the engine running, 
it will idle at the speed called for in the 8 volt table location. I figured 
this one out by trial and error and error and error and error.....
  No one (including the creator of the definition file) has been able to 
offer any additional insight.  I simply put 750 in all cells of this table 
and the engine idles at 750 rpm.
  Probably not the most helpful advice but...
Later,
David



----- Original Message ----- 
From: +ACI-Steve Ravet+ACI- +ADw-Steve.Ravet+AEA-arm.com+AD4-
To: +ADw-gmecm+AEA-diy-efi.org+AD4-
Sent: Sunday, July 09, 2006 9:08 PM
Subject: RE: +AFs-Gmecm+AF0- 305 TBI Hesitation


+AD4APg-
+AD4APg- THis one has plagued me for a year now and like a man it is
+AD4APg- finally time to ask for help.
+AD4APg- The Project:
+AD4APg- 305 CID Small block TBI  7747.
+AD4APg- I'M  trying to figure out two things still. I have a high
+AD4APg- idle problem that cannot be lowered by altering convention
+AD4APg- cell settings for the idle. Something in another area is
+AD4APg- holding the idle up to 1100 RPM no matter what is done, it is
+AD4APg- not mechanical. The computer wants to increase the idle in
+AD4APg- gear at a stop sign.
+AD4APg- This might be related as well .If the throttle is opened up
+AD4APg- slowly under load, the engine hesitates or stumbles as though
+AD4APg- it is going lean. If you let off the throttle ( around 1100
+AD4APg- RPM ), it hesitates and
+AD4APg- the engine surges back as though it went suddenly went rich.   Now if
+AD4APg- you step on it Hard, the engine jumps with all kinds of power
+AD4APg- and runs as it should. My question is has any run into this
+AD4APg- before and which cells are responsible or maybe over riding
+AD4APg- the others? I need some more heads on this one....Fred
+AD4-
+AD4- I had a similar problem some time ago, you can search in the archives
+AD4- for +ACI-creepy idle+ACI-.  With a scan tool I could see the +ACI-desired idle rpm+ACI-
+AD4- creeping up while stopped and in gear.  From a fully warmed up desired
+AD4- RPM of 550 it would slowly creep up to 800 or so, opening the IAC to 180
+AD4- or more in the process.  I got used to shifting to neutral when coming
+AD4- to a stop.  While looking into it I discovered that a wiring error meant
+AD4- that my P/N switch had never been connected correctly.  It was always
+AD4- indicating in gear.  (This is a swap project, 350 TBI into an S-10
+AD4- Blazer, I've been driving it for 9 years now).
+AD4-
+AD4- Fixing that, however, did not solve the problem.  Unfortunately I don't
+AD4- know what did solve it, as it just gradually quit doing it.  I checked
+AD4- CTS, VSS, etc. on the scan tool and all were correct.  There were some
+AD4- other suggestions in response to my original post that I never got
+AD4- around to trying, you might try to dig them up.
+AD4-
+AD4- --steve
+AD4-
+AD4-
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