electrics

[ardee_selby]

Hi Dave, Pete and Listers,

Dave & Pete: Finding your exchange, below, on "Lumenition +
Headlights + Tacho" reminded me - must ask about tacho "bounce"
scenario that near got me killed:-(

Events were:
- Fitted lumenition - car more responsive and started easier. Great:-)
- En-route to Dagenham in wet weather (on infamous 3 lane road)
attempted to overtake large truck.
- Some way past, switched on headlights - ignition light comes on -
tacho goes wild - engine dies - oncoming traffic - PANIC!!
- Breathed in as oncoming car passed - 4 into 3 did go - JUST!
- Coasting to a halt behind truck - engine fired up again!?.
- Nowhere safe to stop so crawled on at 30mph - arrived late, still
shaking!

- Spent a LOT of time checking and re-checking to find what I must
have done wrong with the Lumenition (plus all other ignition items
under bonnet and dash etc etc.) Nothing found.
- Used the car for a couple of days - all seemed well, but any
overtaking felt a bit like Russian roulette.

- Problem recurred in damp weather, on a quiet street. Without diesel
roar in left ear could hear a high pitched "scream" coming from the
front.
- "Screaming" was the headlamp relay bouncing - cleaned, dried and
sealed contacts and all "bullet" connectors (did I say Russian
roulette?).
- This seemed to cure the problem. Pulses in lighting circuit were
feeding into the LT circuit, killing the ignition and sending tacho
off the scale.

Questions/doubts I still have though, Listers, are:

1.0 Has this happened to anyone else?
2.0 Would standard set-up have cut out in the same way? or was it
Lumenition sensitivety?
3.0 The Lumenition seemed to survive it's ordeal, but might it have
been damaged?
4.0 Any re-wiring recommendations (other than plugs/earthing/loom
condition) to stop it happening again?

Any help appreciated - Richard (Incident still brings shivers)

--- In lotuselan@y..., "peteandjanet" <peteandjanet@s...> wrote:

bouncing tacho is a known fault and there is info on the archive to
sort it out, I have not got round to it. If you haven't then I can't
offer any ideas.


lighting switch to the dip switch got hot. Also noticed that when I
operated the indicators with the lights on the rev counter went up
and down with the flashing of the indicators. All of this is with the
engine running by the way. Anyway I've checked all the earths and I
can't find anything not properly earthed. To be honest it has me
beat. Has anyone any ideas......pleeeeease.

[elansprint71]

Richard,
You are making me very nervous! I have not yet driven my car with the
headlights on, let alone overtaken anything. Incidentally the car has been
fitted with Carello halogen units, they still look like candles compared to
modern stuff though.

Maybe I should go out and drive around with the lights on tomorrow? Just
back from an excellent blast around the lanes on this lovely summer evening-
eleven year old daughter is beginning to realise why I bought this "old
car".

Pete

-----Original Message-----
From: ***@***.***lto:***@***.***
Sent: 10 August 2001 13:41
To: ***@***.***
Subject: [LotusElan.net] Dangerous Tacho "Bounce" (was electrics)


Hi Dave, Pete and Listers,

Dave & Pete: Finding your exchange, below, on "Lumenition +
Headlights + Tacho" reminded me - must ask about tacho "bounce"
scenario that near got me killed:-(

Events were:
- Fitted lumenition - car more responsive and started easier. Great:-)
- En-route to Dagenham in wet weather (on infamous 3 lane road)
attempted to overtake large truck.
- Some way past, switched on headlights - ignition light comes on -
tacho goes wild - engine dies - oncoming traffic - PANIC!!
- Breathed in as oncoming car passed - 4 into 3 did go - JUST!
- Coasting to a halt behind truck - engine fired up again!?.
- Nowhere safe to stop so crawled on at 30mph - arrived late, still
shaking!

- Spent a LOT of time checking and re-checking to find what I must
have done wrong with the Lumenition (plus all other ignition items
under bonnet and dash etc etc.) Nothing found.
- Used the car for a couple of days - all seemed well, but any
overtaking felt a bit like Russian roulette.

- Problem recurred in damp weather, on a quiet street. Without diesel
roar in left ear could hear a high pitched "scream" coming from the
front.
- "Screaming" was the headlamp relay bouncing - cleaned, dried and
sealed contacts and all "bullet" connectors (did I say Russian
roulette?).
- This seemed to cure the problem. Pulses in lighting circuit were
feeding into the LT circuit, killing the ignition and sending tacho
off the scale.

Questions/doubts I still have though, Listers, are:

1.0 Has this happened to anyone else?
2.0 Would standard set-up have cut out in the same way? or was it
Lumenition sensitivety?
3.0 The Lumenition seemed to survive it's ordeal, but might it have
been damaged?
4.0 Any re-wiring recommendations (other than plugs/earthing/loom
condition) to stop it happening again?

Any help appreciated - Richard (Incident still brings shivers)

--- In lotuselan@y..., "peteandjanet" <peteandjanet@s...> wrote:

bouncing tacho is a known fault and there is info on the archive to
sort it out, I have not got round to it. If you haven't then I can't
offer any ideas.


lighting switch to the dip switch got hot. Also noticed that when I
operated the indicators with the lights on the rev counter went up
and down with the flashing of the indicators. All of this is with the
engine running by the way. Anyway I've checked all the earths and I
can't find anything not properly earthed. To be honest it has me
beat. Has anyone any ideas......pleeeeease.









reserved.

[Rob_LaMoreaux]

Don't have one so don't know.


Possibly, but it would most like manifest itself as a misfire with regular
points, and the car would have stumbled instead of dying completely.

My guess is that the bouncing +12VDC caused the Lumenition sensor to false
trigger. The Lumenition may have a protection mode when it sees too fast of
trigger, or it may have been triggering the coil at a VERY rapid constant
pace, thus not producing enough spark to fire a cylinder, or firing
cylinders constantly. Then again the voltage going to the sense side of the
Lumenition may have been insufficeint for it to operate.

Points would not false trigger, but the current to the coil could be
reduced causing a misfire.


Since it continues to work, probably no damage was done. Automotive
ignition systems are require to survive some pretty ugly conditions such as
-24VDC. As such it should be able to survive this. I suspect they used an
off the shelf part for the ignition drive and these parts would survive
what you describe easily.


Run separate ground to the headlights and block from the battery ground in
the boot. Next separate the lumenition power (not the coil power) from the
headlight power somplace as close to the battery as possible. If I was real
concerned about this I would put a blocking diode and a large capacitor
between the lumenition and the rest of the cars +12VDC. This would clean up
any noise like this. I don't think this is that common and occurance though
and separating the ignition power from the rest of the car, and keeping the
connectors clean should eliminate it unless the Ghost of Colin has come to
live in you car.

I ran separate grounds to each part of the electrical system including a 4
gauge ground wire to the engine block, and I cleaned and greased all of the
bullet connectors. I still had the car die on me, but I was able to move
things around and get it home. I later found the offending bullet connector
and tightened it up so it doesn't slip out again.

Rob LaMoreaux
Ann Arbor, MI 48108-1273
Home: 734-971-5583
Work: 734-822-9696
Fax: 734-973-1103
Home email: ***@***.***
Work email: ***@***.***
Too many Hobbies.... Too Little Time
1969 Lotus Elan....It's not a restoration, it's a never-ending adventure.

[ardee_selby]

Rob,
Many thanks for advice - will add it to my do-it-again
list. Guess the moral is to treat loom connections as
any other maintenance item. As for a ghost, from other
"incidences" I'm convinced there's something afoot
(was whilst working under nose area that wood fell off
house and smashed the front:-(
Richard
--- "Robert D. LaMoreaux"
<***@***.***> wrote: >



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[gobw2]

Standard point/ coil setup NOT noticeably bothered by relay pulses. If
your system is that sensitive, it means that anytime you switch a load on
or off ( heater, wipers, lights, cigar lighter) it probably false
triggers - for a very brief moment. Perhaps a large capacitor at ignition
input, a choke, or run a separate, fused wire back to the battery, which
is in effect, a huge capacitor, and will dampen pulses, especially high
frequency pulses. Keep ignition wire away from other wiring to prevent
inductance.. Not normally a concern on DC, but pulsing DC acts like AC.
George, 67 elan
On Fri, 10 Aug 2001 12:41:09 -0000 ***@***.***es:

[elansprint71]

I do find that if I switch on some things, the tacho needle falls to zero
for a second or so.

Pete

-----Original Message-----
From: ***@***.***lto:***@***.***
Sent: 12 August 2001 19:03
To: ***@***.***
Cc: ***@***.***
Subject: Re: [LotusElan.net] Dangerous Tacho "Bounce" (was electrics)


Standard point/ coil setup NOT noticeably bothered by relay pulses. If
your system is that sensitive, it means that anytime you switch a load on
or off ( heater, wipers, lights, cigar lighter) it probably false
triggers - for a very brief moment. Perhaps a large capacitor at ignition
input, a choke, or run a separate, fused wire back to the battery, which
is in effect, a huge capacitor, and will dampen pulses, especially high
frequency pulses. Keep ignition wire away from other wiring to prevent
inductance.. Not normally a concern on DC, but pulsing DC acts like AC.
George, 67 elan
On Fri, 10 Aug 2001 12:41:09 -0000 ***@***.***es:

[ardee_selby]

George/Pete
Thanks for help George - will certainly do something
about it. As far as HF pulses were concerned, the
tacho didn't drop to zero but "saw" at least 8500!
Can't recall any zeroing effect after cleaning up
contacts though.

Richard

--- peteandjanet <***@***.***> wrote:


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[ardee_selby]

Re: This phenomenum. Tried to get advice from both
Lumenition and Smiths. No reply from Lumen'. Letter
from Smiths was a great help. (Please don't laugh at
date!:-))
<http://groups.yahoo.com/group/lotuselan/files/Tach/Smiths_Tacho_Letter.jpg>
Thanks again Rob, George. This list is great!
Richard

P.S. FWIW have also uploaded generic article on tachos
in same folder
<http://groups.yahoo.com/group/lotuselan/files/Tach/>

--- peteandjanet <***@***.***> wrote:


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[kstrutt1]

I had a similar problem on My TR some years ago when the electric
cooling fan came on, it turned out that with the ballast resisor type
ignition the and the voltage drop from the fan the coil voltage was
dropping to 4 volts, and consequently misfiring. My solution was to
wire the fan load directly from the battery via a fuse and relay and
fit A 12v sports Coil, deleting the ballast resistor altogether.
I have never had any problem on My +2 with lumentation and halogen
headlamps using the standard wiring.


Kevin +2S130

[Harald S. Feeß]

Had this problem too, but with normal ignition.
It was solved by throwing out the "Anti-Theft-Switch"
(in the glove box).

Harry
Munich, Germany
71 Elan Sprint

[gobw2]

any noise that is read as pulses will make tach read high. a zero
reading sounds like another, unrelated problem of supply voltage or
ground path integrity. George
On Sun, 12 Aug 2001 12:20:15 -0700 (PDT) Richard Selby
<***@***.***> writes: