Re[2]: Holley Pro-Jection

[Colin Gebhart <colin@xxxxxxxxxxxxxxx>]

Hi George,

I would suggest thinking about switching your Holley ECU for a
MegaSquirt.

http://www.thegebharts.com/msindex.html

I posted info about it a year or so ago, but the project in general is
progressing nicely. +80 documented installs and probably many more
undocumented ones because over 1000 kits have been sold.

http://members.shaw.ca/megasquirt/itruns.htm

I have built 2 so far but due to not finishing up ancillary truck
installation problems, my Scout has yet to run on one. Those who have
switched from the Holley to MS have sung like angels and pulled out
the proverbial pail o gas for a Holley BBQ - Carter style.

Even more tempting and in development is UltraMegaSquirt which will
integrate MS, wideband o2 controller, and wasted spark ignition
computer a la Ford EDIS. Further down the road is MegaJolt, an ion
ignition system that will provide knock detection, PPP sensing and
possibly AFR trimming.

Ok, I'll cut the sermonizing, but this stuff is addictive.

Friday, July 25, 2003, 2:03:14 PM, you wrote:

GBH> I added the closed loop oxygen sensor a little while ago. Now I have a
GBH> new problem. When I come to a stop, after a few seconds, Sometimes the
GBH> idle will become rough and the vacuum will start to drop. I didn't have
GBH> this problem until I added the oxygen sensor. Looks like I've got some
GBH> trouble shooting ahead of me. If you have any suggestions on where to
GBH> start feel free to let me know.

Since the Holley is not open-source and I am not that interested in it,
I am not sure exactly how it operates.  However, this sounds like a
classic case of closed loop control at too low of an engine speed.
Idle is a special operating case that generally requires richer
mixtures than a narrow band o2 sensor can detect ~14.2-14.9 AFR.
Additionally at low speeds, often the o2 sensor's fire will go out and
it can not detect anything unless it is an electrically heated one.
Or tertiarially you could have a poor o2 signal ground unless it is a
4-wire one.

To cure what ails you, I would -
1 get a MS or
2 find out what kicks the Holley off of closed loop and try to adjust
3 replace that likely 1 wire o2 sensor with a 4 wire electrically
heated one (ie AC DELCO 213-360 and PT818 is the matching pigtail.)
Narrowband o2 sensors are virtually interchangeable with the exception
of zirconium ones which are exceedingly rare (I think mostly 80's
Japaneese cars)

Good Luck,
Colin                            
mailto:colin@domain.elided
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