Page:
Home > Help Needed / General Tech Chat > Alternator / Overrun Issues

wil_h

User Avatar

9258 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

I've re-wired my Megasquirt so that it is now fed by an ignition switched relay. The switched supply is the old coil supply on the same switched feed from the ignition barrel as the alternator energise supply (i.e the one for the ignition light). The MS is then fed with a supply directly from the battery through the switched relay.

Keeping up so far?

Now the car starts and runs as expected. But when i turn the ignition off the charging light comes on and the car just keeps on running. a poke around with the meter shows around 5V on the supply for the new relay (and hence ignition light).

Before, I presume that 5V was not enough to keep the MS going, but it is now enough to keep the relay energised.

So, where is this 5V from? is it an alternator fault?

Any clues as it's doing my nut in.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph



On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


wez

1226 Posts
Member #: 9271
Post Whore

Stoke on Trent

Prob not relivant but when my alternator went on my old astra sport it kept the whole circuit perminatly live till the battery went flat. Could be something similar??

one day boost will be mine!

On 10th Mar, 2012 Joe C said:
TBH peple stick it everywhere... and theres merits to each...


wil_h

User Avatar

9258 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

This is interesting. Especially as my car is a '77. Might give it a go.

http://www.mgexperience.net/article/mgb/ignition-run-on.pdf

Fastest 998 mini in the world? 13.05 1/4 mile 106mph



On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


almichie

User Avatar

824 Posts
Member #: 2065
Post Whore

Wiltshire

Is it back feeding an earth through the relay coil?

On 7th Nov, 2011 apbellamy said:
Shaft seems nice and snug


On 24th Mar, 2012 apbellamy said:
no no no no, you need more boost! you can never ever come on here and say I have enough boost, that's just silly.


On 29th Mar, 2010 Star Mag said:
these give no problems with good head


almichie

User Avatar

824 Posts
Member #: 2065
Post Whore

Wiltshire

Like I said... You might need a relay with a diode in, or fit a diode so you don't get a feed back into the circuit when off

On 7th Nov, 2011 apbellamy said:
Shaft seems nice and snug


On 24th Mar, 2012 apbellamy said:
no no no no, you need more boost! you can never ever come on here and say I have enough boost, that's just silly.


On 29th Mar, 2010 Star Mag said:
these give no problems with good head


John

User Avatar

10023 Posts
Member #: 1456
Mongo

Barnsley, South Flatcapshire

This is happening to us with the van!

If something is worth doing, it's worth doing half of.


wil_h

User Avatar

9258 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

I'm off to buy a diode later

Fastest 998 mini in the world? 13.05 1/4 mile 106mph



On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


apbellamy

User Avatar

16540 Posts
Member #: 4241
King Gaycharger, butt plug dealer, Sheldon Cooper and a BAC but generally a niceish fella if you dont mind a northerner

Rotherham, South Yorkshire

Keep us updated. The van has the same symtoms. We have to pull the relay to stop it sometimes. It's also been killing batteries on a regular basis...

On 11th Feb, 2015 robert said:
i tried putting soap on it , and heating it to brown , then slathered my new lube on it

*hehe!*


wil_h

User Avatar

9258 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

I'll buy 2 diodes and if it works I'll bob one in the post for you.

Try measuring the relay coil voltage when it's overrunning, this should tell you if it's the same problem.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph



On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


apbellamy

User Avatar

16540 Posts
Member #: 4241
King Gaycharger, butt plug dealer, Sheldon Cooper and a BAC but generally a niceish fella if you dont mind a northerner

Rotherham, South Yorkshire

Good plan. I'll swap you for a push rod at Avon.

On 11th Feb, 2015 robert said:
i tried putting soap on it , and heating it to brown , then slathered my new lube on it

*hehe!*


Paul S

User Avatar

8604 Posts
Member #: 573
Formerly Axel

Podland

This happens to the 998 ti ocaissionally.

I think it is back feeding through the ignition light. Diode should sort it out.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."


wil_h

User Avatar

9258 Posts
Member #: 123
Post Whore

Betwix Harrogate and York

It's a deal.


On 23rd Jun, 2011 apbellamy said:
Good plan. I'll swap you for a push rod at Avon.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph



On 2nd Jan, 2013 fastcarl said:

the design shows a distinct lack of imagination,
talk about starting off with a clean sheet of paper, then not bothering to fucking draw on it,lol

On 20th Apr, 2012 Paul S said:
I'm mainly concerned about swirl in the runners caused by the tangential entry.


apbellamy

User Avatar

16540 Posts
Member #: 4241
King Gaycharger, butt plug dealer, Sheldon Cooper and a BAC but generally a niceish fella if you dont mind a northerner

Rotherham, South Yorkshire

I wonder where I put that push rod...

On 11th Feb, 2015 robert said:
i tried putting soap on it , and heating it to brown , then slathered my new lube on it

*hehe!*

Home > Help Needed / General Tech Chat > Alternator / Overrun Issues
Users viewing this thread: none. (+ 1 Guests)  
To post messages you must be logged in!
Username: Password:
Page: