Re: ECU Bug

[stans4@ibm.net (Stan Schaefer)]

Not sure about a "bug" as such, it's a documented intentional design
feature on some of the control units that the fuel is cut while the
RPM is high and the throttle is closed, e.g., while coasting down
hill.  After the engine slows down to idle speed, fuel injection is
started back up.  I think I saw it in the Bosch FI manual, but not
sure.  Apparently it wasn't well received by the driving population,
later ones didn't have it.  I have one of these controllers.  The idea
was to save some gas.  It does kind of give the impression of an old
lawn mower while driving in traffic and coasting to the next light.
The odd thing is that the PN  label is a black "D" suffix one, just
like my other one that doesn't have it.  Kind of hard to tell by
looking then. This is on a '71 SB.  Have never had it happen while the
gas pedal was depressed, I suppose it could happen if the accel side
of the throttle position switch was open while the butterfly was still
open, misadjusted or dirty, in other words.  I got 31.5 mpg with this
controller  between Sparks and Winemmuca, NV, with 800 lbs. of stuff,
plus me and the cat.


On Thu, 25 Jun 1998 11:32:18 -0400, you wrote:

>Some of the "older" list members may remember a thread about a "bug" in the
>early ECU in FI engines, I think this even documented somewhere.
>
>The anomaly observed is as follows: when the car is coasting and when the
>throttle is in a particular position, the ECU will shut-off all the
>injectors until the throttle is depressed or released. The symtom is that
>the engine will drop to idle although the driver will have the gas pedal
>depressed.
>
>Anybody remember anything about this?
>
>Steve B.