[Gmecm] Cruise Ideas and Ostrich/Pocket Romulator

[David Allen]

  Hey, I had the same trouble with the agressive cruise issue on my Nova.
The cruise components came from a the junkyard, no idea what car.  It's now
on a TBI V8.  It would "wear you out" with the surging and hunting. Plus it
would hunt around so much going uphill that it would use up all the vacuum
in the vacuum canister and loose speed.  It was not good...  This is the
cruise setup with the electronic control module that reads off a speedometer
optical VSS sensor.  I guess this is what you have too?
  I tried all the normal fixes of cleaning the vac and vent solenoid valves,
etc.  After suffering through a 9 hour drive like this, I tried making a
restrictor oriface for each of the solenoids.  This slowed down the response
of the servo.
  The VAC (increase) valve has a pinhole oriface.  The VENT (decrease) valve
has one about 3 times that size.  This setup works very well and is at least
as stable as the factory cruise on our family's 89 LeSabre and 95 Aurora. I
filled the parts with JB Weld and re-drilled the orifaces. Originally the
VAC valve had a 1/16 or larger oriface, and the VENT valve had no oriface at
all (wide open).  It has been a year since adding the cruise to this car - i
think that is how it was.
  I don't know if there is any tunability in the control unit.  I read it
uses a form of analog PID.  I know it has numerous analog components on the
board but I haven't really studied it.  You could probably adjust some
resistors and reduce the proportional gain.
   I didn't take any pictures of this mod, it was done 500 miles from home
in the hopes of a less stressful ride back home!
   As for the programming hardware- I can't help with the comparison because
I have only used one- the Transtronics Pocket Romulator II.  It works
flawlessly.  It can operate the ECM with or without the laptop connected.
It can be left in semi-permanently without need for the computer or even the
computer cable to be in place.  I leave it in as I drive a few days then
only connect the computer when I want to make an adjustment to the
calibration. Once it is dialed in perfectly, I can make a "real" chip for
permanent use.
  If your car don't use a MEMCAL, there's a way you can plug it into the
ECM's EPROM socket without desoldering the socket from the ECM board. Plug
an IC socket onto the end of the ROMulator cable. Then the male terminals of
the IC socket will fit into the factory EPROM socket in place of an EPROM
and carrier assembly.  You have to use a high-quality round-pin socket.  It
takes careful alignment to make it work but it is not that difficult and
definatley easier (and less risky) than removing the original EPROM socket.
This way you can re-use the original EPROM carrier.  (I had to buy an ECM
for this car and I haven't done anything they could use as an excuse to not
warranty it if it fails.)
  Best of luck!
David


----- Original Message ----- 
From: "Cowen" <captain_krill at yahoo.com>
To: <gmecm at diy-efi.org>
Sent: Friday, September 09, 2005 5:51 PM
Subject: [Gmecm] Cruise Ideas and Ostrich/Pocket Romulator


> Hey folks, I'm about to buy all the programming tools.
>  Anyone have opinions on the relative merits of the
> Ostrich vs the Pocket-ROMulator?
>
> Also, after I swapped MPFI for the carb on my 3.4l V6,
> the cruise control is overly aggressive.  It appears
> to be happening because the MPFI throttle plate is
> operated by a shorter lever arm that the old carb was,
> so the same distance traveled by the cruise control
> cable results in much more aggressive throttle inputs!
>  I know this isn't really a GM-EFI question, but the
> good people reading this newsletter have a variety of
> automotive/electronic interests.  I've been searching
> for info on fine tuning how the cruise control acts,
> and I've reached the end of the line.  I've had little
> success with Google and Metacrawler, does anyone have
> any suggestions on how to fix one of the very few
> problems with the MPFI installation?  Suggestions on
> where else to look?  Thanks.
> Duncan
>
>
>
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