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That's a fairly common problem with electronic ignition systems and rev
limiters. Generally they either work perfectly from the day you unwrap them,
or they become one more gremlin that you have to waste time with. My engine
seems to run a little better with electronic ignition, and the rev limiter
is nice to have, but I switched back to a dual point distributor and a Delco
coil after a few funny problems that I couldn't be sure wouldn't surface
again. In one case I was getting a low RPM miss and a very warm coil. I
added a ballast resistor (contrary to the instructions) and it went away.
Another time my rev limiter seemed to be wandering, cutting out as low as
5200 and as high as 6200. Replacing the unit cured it, and I was able to
remove the ballast resistor without the low speed miss returning (though I
had swapped the unit and the coil before adding the ballast resistor with no
change in behavior).
-----Original Message-----
From: Roger Beasley [mailto:beeline@iline.com]
Sent: Monday, May 03, 1999 7:38 AM
To: FOT@autox.team.net
Cc: Phillip Babcock
Subject: Fw: Luminition Ignition/Rev Limiter
Amici,
I don't know how many of you are running rev limiters. The text below
details some of my recent (and first) experience with a limiter, and the
manufacturer's response.
I have been kicking myself for screwing up six or seven race weekends while
I fooled around with this problem, but it all goes back to lack of knowledge
of the product on my part. That, and not really thinking out the problem
very well. I had convinced myself that it couldn't be the rev limiter
because it didn't act like I thought a rev limiter would.
My question to the group is, how much cushion if any, do you set into the
limit? If your target shift point is 6,000rpm, where do you set the
limiter?
----------
From: Adrian Goodsell <autocar@dircon.co.uk>
To: beeline@iline.com
Subject: Re: Luminition Ignition/Rev Limiter
Date: Wednesday, April 28, 1999 11:50 AM
Mr Beasley The Lumenition Rev Limiter is a full cut device designed to cut
all sparks above the set rev limit. To that end it will prevent an
acceleration over revving but will not prevent a mechanical driven over rev
such as selecting 2nd instead of 4th or an inertial effect. The symptoms
you describe may be an effect of the coil waveform on the device. It is
possible that the particular characteristics of coil, leads, spark gap and
combustion requirements are causing the coil negative waveform to feedback
extra signals into the rev limiter that trick it into seeing a higher engine
speed than real. I have seen this on some occasions but it does not appear
to be predictable. It may be that something you have changed recently has
affected this if the system was operating correctly when first fitted.
Possibly altering spark gaps or a different coil may have an effect. When
seen it may only happen whilst the engine is under load and the rev limiter
reads the rpm correctly if there is no load on the engine. The other
possibility is that the rev limiter is operating at its set rpm but the coil
is still producing a spark (even with its voltage limited) enough to fire
the combustion. This can occur with high energy coils or with the engine at
light loads. Even limited a standard coil may provide a 3 to 4 Kv spark
which can be just enough to fire a light mixture. A rolling road with
ignition scope facilities may be able to further trace exactly what is
happening. When the rev limiter cuts in the ignition trace will change from
the normal pattern to a square low voltage pattern. The coil negative
pattern may show signs of multi sparking or high voltage noise. If the
problem persists we do have a Micro Dynamics rev limiter which offers
similar performance but has a slightly different input filter which may
operate more successfully with your particular setup. Regards Customer
Support
-----Original Message-----
From: Roger Beasley <beeline@iline.com <mailto:beeline@iline.com>>
To: autocar@denaploy.co.uk <mailto:autocar@denaploy.co.uk>
<autocar@denaploy.co.uk <mailto:autocar@denaploy.co.uk>>
Date: Monday, April 19, 1999 8:30 PM
Subject: Luminition Ignition/Rev Limiter
Dear Sirs:
Sometime last year, I purchased a Luminition amplifier kit and rev limiter
from your American distributor, XK's Unlimited. The units were installed on
my vintage Triumph TR4 racecar.
Initially, all was well with the unit but after some subsequent work due to
cracked intake manifold, etc, the rev limiter must have inadvertently been
reset to a lower limit. For some time and a number of race meetings, the
car would pull strongly to 5100 rpm whereupon, it began to burbble or "knit"
as my tuner put it. At that point, I chose to shift. But if pressed, I was
able to pull through on up near the desired redline of 6000. The problem
was not so pronounced in first and second gear as in third and fourth.
Because of the ability to pull on up past the initial point where engine
miss began, I assumed it was a carbueration problem. However, this past
weekend, I made an appointment with my engine builder for a test day at a
nearby track. After much experimentation with mixture and no improvement,
he finally decided to eliminate the rev limiter from the equation. The
limiter proved to be the problem as without it, the engine would pull
strongly up the range to the desired limit. Reattachment of the limiter
brought back the problem. We further experimented with increasing the
adjustment of the limiter until it only began to affect the engine at
approximately 6400 rpm allowing for a cushion on the normal 6000 working
limit.
My question is this, how exactly does the unit work to limit revs? Is it an
extremely soft cut which is designed to allow an additional amount of revs
after the initial onset? The main use I have for a limiter is to prevent
zinging the engine in case of a missed shift. And, I don't wish to come up
against the limiter on each shift. Am I putting your unit to its proper
application?
Roger Beasley
Cape Coral, Fl
1962 TR4 Racecar
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<DIV><FONT color=#0000ff face=Arial size=2><SPAN
class=290284415-03051999>That's
a fairly common problem with electronic ignition systems and rev limiters.
Generally they either work perfec</SPAN></FONT><FONT
face="Times New Roman"><FONT size=2><SPAN class=290284415-03051999><FONT
color=#0000ff face=Arial>tly from the day you unwrap them, or they become
one more gremlin that you have to waste time with. My engine seems to run a
little better with electronic ignition, and the rev limiter is nice to have,
but
I switched back to a dual point distributor and a Delco coil after a few funny
problems that I couldn't be sure wouldn't surface again. In one case I was
getting a low RPM miss and a very warm coil. I added a ballast resistor
(contrary to the instructions) and it went away. Another time my rev limiter
seemed to be wandering, cutting out as low as 5200 and as high as 6200.
Replacing the unit cured it, and I was able to remove the ballast resistor
without the low speed miss returning (though I had swapped the unit and the
coil
before adding the ballast resistor with no change in behavior).
</FONT></SPAN></FONT></FONT></DIV>
<DIV><FONT face="Times New Roman"><FONT size=2><SPAN
class=290284415-03051999></SPAN></FONT></FONT> </DIV>
<DIV><FONT face="Times New Roman"><FONT size=2><SPAN
class=290284415-03051999></SPAN></FONT></FONT> </DIV>
<DIV><FONT face="Times New Roman"><FONT size=2><SPAN
class=290284415-03051999> </SPAN>-----Original
Message-----<BR><B>From:</B>
Roger Beasley [mailto:beeline@iline.com]<BR><B>Sent:</B> Monday, May 03, 1999
7:38 AM<BR><B>To:</B> FOT@autox.team.net<BR><B>Cc:</B> Phillip
Babcock<BR><B>Subject:</B> Fw: Luminition Ignition/Rev
Limiter<BR><BR></DIV></FONT>
<BLOCKQUOTE style="MARGIN-RIGHT: 0px"></FONT>
<P><FONT color=#000000 face=Arial size=2>Amici,<BR><BR>I don't know how many
of you are running rev limiters. The text below details some of my
recent (and first) experience with a limiter, and the manufacturer's
response.
<BR><BR>I have been kicking myself for screwing up six or seven race
weekends while I fooled around with this problem, but it all goes back to
lack
of knowledge of the product on my part. That, and not really thinking
out the problem very well. I had convinced myself that it couldn't be
the rev limiter because it didn't act like <U>I thought </U>a rev limiter
would.<BR><BR>My question to the group is, how much cushion if any, do you
set
into the limit? If your target shift point is 6,000rpm, where do you
set
the limiter?<BR><BR>----------<BR>From: Adrian Goodsell <<FONT
color=#0000ff><U>autocar@dircon.co.uk</U><FONT color=#000000>><BR>To:
<FONT
color=#0000ff><U>beeline@iline.com</U><FONT color=#000000><BR>Subject: Re:
Luminition Ignition/Rev Limiter<BR>Date: Wednesday, April 28, 1999 11:50
AM<BR><BR>Mr Beasley<FONT size=3> <FONT size=2>The Lumenition Rev
Limiter is a full cut device designed to cut all sparks above the set rev
limit. To that end it will prevent an acceleration over revving but
will
not prevent a mechanical driven over rev such as selecting 2nd instead of 4th
or an inertial effect.<FONT size=3> <FONT size=2>The symptoms you
describe may be an effect of the coil waveform on the device. It is
possible that the particular characteristics of coil, leads, spark gap and
combustion requirements are causing the coil negative waveform to feedback
extra signals into the rev limiter that trick it into seeing a higher engine
speed than real. I have seen this on some occasions but it does not
appear to be predictable. It may be that something you have changed
recently has affected this if the system was operating correctly when first
fitted. Possibly altering spark gaps or a different coil may have an
effect. When seen it may only happen whilst the engine is under load
and
the rev limiter reads the rpm correctly if there is no load on the
engine.<FONT size=3> <FONT size=2>The other possibility is that the rev
limiter is operating at its set rpm but the coil is still producing a spark
(even with its voltage limited) enough to fire the combustion. This can
occur with high energy coils or with the engine at light loads. Even
limited a standard coil may provide a 3 to 4 Kv spark which can be just
enough
to fire a light mixture.<FONT size=3> <FONT size=2>A rolling road with
ignition scope facilities may be able to further trace exactly what is
happening. When the rev limiter cuts in the ignition trace will change
from the normal pattern to a square low voltage pattern. The coil
negative pattern may show signs of multi sparking or high voltage noise.<FONT
size=3> <FONT size=2>If the problem persists we do have a Micro
Dynamics
rev limiter which offers similar performance but has a slightly different
input filter which may operate more successfully with your particular
setup.<FONT size=3> <FONT size=2>Regards<FONT size=3> <FONT
size=2>Customer Support<FONT size=3> </P>
<P><FONT size=2><B>-----Original Message-----</B><BR><B>From:</B> Roger
Beasley <<FONT color=#0000ff><U>beeline@iline.com</U><FONT color=#000000>
<<FONT color=#0000ff><U>mailto:beeline@iline.com</U><FONT
color=#000000>>><BR><B>To: </B><FONT
color=#0000ff><U>autocar@denaploy.co.uk</U><FONT color=#000000> <<FONT
color=#0000ff><U>mailto:autocar@denaploy.co.uk</U><FONT color=#000000>>
<<FONT color=#0000ff><U>autocar@denaploy.co.uk</U><FONT color=#000000>
<<FONT color=#0000ff><U>mailto:autocar@denaploy.co.uk</U><FONT
color=#000000>>><BR><B>Date:</B> Monday, April 19, 1999 8:30
PM<BR><B>Subject: </B>Luminition Ignition/Rev Limiter<BR><BR>Dear
Sirs:<BR><BR>Sometime last year, I purchased a Luminition amplifier kit and
rev limiter from your American distributor, XK's Unlimited. The units
were installed on my vintage Triumph TR4 racecar. <BR><BR>Initially,
all
was well with the unit but after some subsequent work due to cracked intake
manifold, etc, the rev limiter must have inadvertently been reset to a lower
limit. For some time and a number of race meetings, the car would pull
strongly to 5100 rpm whereupon, it began to burbble or "knit" as my tuner put
it. At that point, I chose to shift. But if pressed, I was able
to
pull through on up near the desired redline of 6000. The problem was
not
so pronounced in first and second gear as in third and fourth.
<BR><BR>Because of the ability to pull on up past the initial point
where engine miss began, I assumed it was a carbueration problem.
However, this past weekend, I made an appointment with my engine
builder
for a test day at a nearby track. After much experimentation with
mixture and no improvement, he finally decided to eliminate the rev limiter
from the equation. The limiter proved to be the problem as without it,
the engine would pull strongly up the range to the desired limit.
Reattachment of the limiter brought back the problem. We further
experimented with increasing the adjustment of the limiter until it only
began
to affect the engine at approximately 6400 rpm allowing for a cushion on the
normal 6000 working limit.<BR><BR>My question is this, how exactly does the
unit work to limit revs? Is it an extremely soft cut which is designed
to allow an additional amount of revs after the initial onset? The main
use I have for a limiter is to prevent zinging the engine in case of a missed
shift. And, I don't wish to come up against the limiter on each shift.
Am I putting your unit to its proper application?<BR><BR>Roger
Beasley<BR>Cape Coral, Fl<BR>1962 TR4 Racecar</P>
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