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Petronix idle changes
#1
Matticon Avatar
Matticon Matt WROBEL
Richmond, BC, Canada   CAN
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1968 Triumph TR250
1974 MG MGB "Beatrice"
Hello,

Anyone have a petronix igniter 2 system that is affected when you turn on the headlights?

Seems mine is affected as it can drop the idle and conks the vehicle out after it has been on a good run for over 30min. At speed and higher revs no problem.

Turn the headlights off and the car idles nice.

Matt

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Re: Petronix idle changes
#2
ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
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1971 MG MGB
My Ignitor II works great.

I suspect that one of two things is happening. The lights may be loading the electrical system and dropping the voltage. If you have poor connections or a weak battery then there might be a voltage drop at the Pertronix. Use a meter to measure the voltage to the red (power) lead of the Ignitor II with and without the lights on.

The other possibility is that when the lights are on, the alternator ramps up its output and is creating some noise on the power line that is bothering the Ignitor II. If that is the case, try putting a 20 uF capacitor between the red power lead and ground to filter out any noise.


Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: Petronix idle changes
#3
Donthuis Avatar
Donthuis Don van Riet
Rijswijk, ZH, Netherlands   NLD
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1972 MG MGB MkIII
If your 1974 still has its idle tuned lean on high rpm like most smog control engines had, this is quite sensitive to loading by the alternator. I used to have the same drop in idle rpm in the past.
Now that I converted my vac system for manifold to ported, the effect of the loading the alternator by the headlights is almost gone, idle no longer drops cool smiley

PS I have the Accuspark, not the Pertronix, but never noticed any feedback from the battery voltage level to this unit.
Protection against voltage spikes is something else, connect a condensor on the Pertronix switched battery feed to mass for additional protection against this potential hazard... thumbs up

In reply to # 3363765 by Matticon Hello,

Anyone have a petronix igniter 2 system that is affected when you turn on the headlights?

Seems mine is affected as it can drop the idle and conks the vehicle out after it has been on a good run for over 30min. At speed and higher revs no problem.

Turn the headlights off and the car idles nice.

Matt

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Re: Petronix idle changes
#4
B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
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1950 Willys Jeep Pickup "Ratrod"
1964 Land Rover Series IIA
1971 MG MGB
Did you switch to a 1.5 Ohm coil with no ballast wire, or are you still running the factory 3 Ohm coil? How many volts do you have at the coil + terminal with the ignition on, car not running?


jeff@advanceddistributors.com

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Re: Petronix idle changes
#5
LaVerne Avatar
LaVerne LaVerne Downey
Fruita, CO, USA   USA
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1954 MG TF "Green Hornet"
1969 MG MGB "The Beater"
1979 Triumph TR8 "Turd 8"
I learned a long time ago that the Pertronix needs at least 12 volts to fire. It's very possible with the lights on at idle you are pulling the voltage below 12 volts thus causing the failure.

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Re: Petronix idle changes
#6
Tar Trekka Avatar
Tar Trekka Ross H
Sydney, NSW, Australia   AUS
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1968 MG MGB MkII "Miss B"
Hi there,

I have a Petronix Ignitor 1 on my MGB.

After reading this Thread, I contacted Petronix re the "Minimum Voltage Required" for this unit to operate.

Petronix said the Ignitor 1 can operate on as little as 8 Volts.

If you go to the Contact Link on their Web Site, you can ask about other "Petronix Models".

Ross H

Any day above the ground is a great day, especially "Driving Miss B".


Any day above the ground is a great day, especially "Driving Miss B".

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Re: Petronix idle changes
#7
ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
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1971 MG MGB
Don's point is very valid - a lean tuned car may have very little horsepower at idle. Turning on the headlamps (~120 watt load + tail lights and running lights - say 200 watts) is about 1/3 HP load. That might be the cause of the idle drop. Try raising your idle speed by 100 RPM and see what that gives you.

Also check your tach to make sure it is accurate. It isn't unusual to have 100 or 200 RPM error at idle - so you think you are set to (say) 900 RPM and you are only set to 700 RPM.


Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: Petronix idle changes
#8
Matticon Avatar
Matticon Matt WROBEL
Richmond, BC, Canada   CAN
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1968 Triumph TR250
1974 MG MGB "Beatrice"
Thanks everyone for their suggestions.

I cleaned all the connections, dielectric greased them, from the battery to the coil.

I checked with a volt meter. 11.75 volts without headlights. 11.4 volts with headlights.

There is a noticible slight drop of about 50-100 rpm.

I adjusted the mixture and upped the idle speed and everything seems to run fine.

The causation of stalling out is associated to a total other issue of my idle dropping a fair amount as the car warms up. I think turning the headlights on just makes it start sooner due to that 50rpm drop. if I am already down at 750rpm. (Car is really warm (at N) sitting in stop and go traffic for over 30min) it just drops it low enough to stall it out.

Researching the other problem now. winking smiley

Thanks for all the help! Why I love this forum!

Matt

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Re: Petronix idle changes
#9
falconbobb Gerald Dalton
Crestwood, KY, USA   USA
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1975 MG MGB
I experience the same as the OP, lights on ,idle drop . will have to check my stuff.

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Re: Petronix idle changes
#10
ingoldsb Avatar
ingoldsb Silver Member Terry Ingoldsby
Calgary, AB, Canada   CAN
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1971 MG MGB
Quote: The causation of stalling out is associated to a total other issue of my idle dropping a fair amount as the car warms up.

This sounds like it is running rich. HS4 carbs definitely run richer when hot than when warm. HIF4 carbs are supposed to have a temperature compensation device - but I'm not sure that it is very effective. Perhaps it is overcompensating and taking you lean. When you go too lean, the idle drops suddenly and quite dramatically. When you go too rich the idle generally drops gradually as the mixture increases. Either way, I think you need some carb tuning.


Terry Ingoldsby
terry.ingoldsby@DCExperts.com

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Re: Petronix idle changes
#11
LaVerne Avatar
LaVerne LaVerne Downey
Fruita, CO, USA   USA
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1954 MG TF "Green Hornet"
1969 MG MGB "The Beater"
1979 Triumph TR8 "Turd 8"
In reply to # 3368544 by Tar Trekka Hi there,

I have a Petronix Ignitor 1 on my MGB.

After reading this Thread, I contacted Petronix re the "Minimum Voltage Required" for this unit to operate.

Petronix said the Ignitor 1 can operate on as little as 8 Volts.

If you go to the Contact Link on their Web Site, you can ask about other "Petronix Models".

Ross H

Any day above the ground is a great day, especially "Driving Miss B".


Things have changed then as the one I have will not fire with less than 12 volts. I was puzzled for a long time why the engine wouldn't fire when it was cranking but fired immediatly when I released the starter. I had the spark go away one day when it was raining...I had the lights, wiper and heater running and my generator wasn't keeping up. Shut off the lights and all was well. Maybe the new units will fire with less voltage but not the unit I have.

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Re: Petronix idle changes
#12
pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
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1958 MG MGA 1500
1961 Austin-Healey Bugeye Sprite
1971 MG MGB GT
1973 MG MGB MkIII
In reply to # 3368840 by LaVerne
In reply to # 3368544 by Tar Trekka Hi there,

I have a Petronix Ignitor 1 on my MGB.

After reading this Thread, I contacted Petronix re the "Minimum Voltage Required" for this unit to operate.

Petronix said the Ignitor 1 can operate on as little as 8 Volts.

If you go to the Contact Link on their Web Site, you can ask about other "Petronix Models".

Ross H

Any day above the ground is a great day, especially "Driving Miss B".


Things have changed then as the one I have will not fire with less than 12 volts. I was puzzled for a long time why the engine wouldn't fire when it was cranking but fired immediatly when I released the starter. I had the spark go away one day when it was raining...I had the lights, wiper and heater running and my generator wasn't keeping up. Shut off the lights and all was well. Maybe the new units will fire with less voltage but not the unit I have.

Fred Winterburn said the one he tested fired down to 6 volts reliably.

Adrian


Home built Eaton M62 Supercharger with 8psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, custom ground high ratio "stock" rocker arms, Maxspeeding rods with Teflon wrist pin buttons, custom aluminum cold air intake, CB Performance computerized ignition, Fidanza 9 pound flywheel, 1.44 exhaust valves in 48cc chamber head, matched manifolds, 2 1/4" exhaust system.


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Re: Petronix idle changes
#13
Tar Trekka Avatar
Tar Trekka Ross H
Sydney, NSW, Australia   AUS
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1968 MG MGB MkII "Miss B"
Hi there,

If you wish to solve your problem permanently, assuming your Battery is in good shape, put a Relay in the Headlight & Heater Motor circuits.

Don't power the Relay from the existing Electrical System, power it from the Heavy Power Cable on the Starter Motor & use at least 6 mm Wire.

I run my Headlights at all times & I found a Relay solved my problem of "Slow Blinkers" & Voltage Drop at the Coil at Idle.

Ross H.

Any day above the ground is a great day, especially "Driving Miss B".


Any day above the ground is a great day, especially "Driving Miss B".



Edited 1 time(s). Last edit at 2016-10-06 04:46 PM by Tar Trekka.

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Re: Petronix idle changes
#14
LaVerne Avatar
LaVerne LaVerne Downey
Fruita, CO, USA   USA
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1954 MG TF "Green Hornet"
1969 MG MGB "The Beater"
1979 Triumph TR8 "Turd 8"
When I quizzed Pertronix years ago they flat out told me what I already knew. Less than 12 volts...no fire. Apparently things have changed.

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Re: Petronix idle changes
#15
Fred Winterburn Avatar
Fred Winterburn Fred W
Ripley, ON, Canada   CAN
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1956 Morgan Plus 4 (+4)
1966 Volvo P1800
Adrian, That's true for the pertronix 1 I bought about 3 years ago for an early sixties Ford V8 dizzy. It would switch to 6V and then abruptly stop below that voltage. Of course the energy would be very low and probably useless below about 8V or 9V, and I am surprised that one wouldn't work below 12V. I'm not a fan of pertronix in any form, but I can see the appeal and would even consider pertronix 2 with some dwell extension, except that I do not believe it can compensate for low battery voltage, only high rpm. I like points because I can see if they are intact and likely to work without getting out a meter and measuring. Fred

In reply to # 3368929 by pinkyponk
In reply to # 3368840 by LaVerne
In reply to # 3368544 by Tar Trekka Hi there,

I have a Petronix Ignitor 1 on my MGB.

After reading this Thread, I contacted Petronix re the "Minimum Voltage Required" for this unit to operate.

Petronix said the Ignitor 1 can operate on as little as 8 Volts.

If you go to the Contact Link on their Web Site, you can ask about other "Petronix Models".

Ross H

Any day above the ground is a great day, especially "Driving Miss B".


Things have changed then as the one I have will not fire with less than 12 volts. I was puzzled for a long time why the engine wouldn't fire when it was cranking but fired immediatly when I released the starter. I had the spark go away one day when it was raining...I had the lights, wiper and heater running and my generator wasn't keeping up. Shut off the lights and all was well. Maybe the new units will fire with less voltage but not the unit I have.

Fred Winterburn said the one he tested fired down to 6 volts reliably.

Adrian


'Anyone who likes liver, can't taste it'
'If you want to repair car electrical systems successfully, learn Ohm's Law'.
'You can't shake hands with a snake'

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