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Help!! Weak Spark!
MakeEverything - 16/4/11 at 04:43 PM

Ive had my car running, but it stopped working whilst testing. At this point the wiring was a mess, so ive replaced it all and still have the same problem with it not running.

Ive swapped the EDIS out (Thanks to Paul (Notts) and Andy Barbet) as well as the coil (Thanks again Andy Barbet). I have a very weak spark, but no RPM signal and it wont fire up.

Fault finding has proven;

15A EDIS Fuse ok
Wiring to EDIS is ok
PIP & SAW continuity ok
VR Sensor New
VR Shielded Cable replaced today
Spark Plugs new (But black from running rich)
Battery good
Cranking voltage 10-11V when on charge
EDIS Modules tried ok (x3)
Coil Pack ok (x2)

I've also had Davegtst look at it, and an AA guy, all have said that it could be the EDIS module. I cant beleive that three modules would be U/S??

I'm out of options now. Any ideas? Will post a diagram of my wiring in a bit.

The only other option i have is to install the 25uF capacitor to try and boost the ignition voltage?

[Edited on 16-4-11 by MakeEverything]


perksy - 16/4/11 at 04:53 PM

Crank sensor gap too big ?


MakeEverything - 16/4/11 at 04:54 PM

Nope. Getting up to 4Vac from it, even though MS isnt seeing the RPM or crank sensor.


doddy - 16/4/11 at 04:54 PM

have you made sure you have good earths of the engine


MakeEverything - 16/4/11 at 04:57 PM

quote:
Originally posted by doddy
have you made sure you have good earths of the engine


Yes, i have continuity between the block, chassis and Ali plate that the electronics are mounted to. There is no difference in potential, and all earths are at the same point.


MakeEverything - 16/4/11 at 05:04 PM

Wiring Problem
Wiring Problem


This is a picture of some of the wiring around the EDIS. It shows the capacitor that i DONT have installed at the moment.


paulf - 16/4/11 at 05:13 PM

The capacitor makes no difference to the spark ,it is there for interference suppression.I have ran with and with out it and it made no difference.If you are getting a spark at all then there is not a problem with the Vr sensor or associated wiring.
Paul


MakeEverything - 16/4/11 at 05:58 PM

quote:
Originally posted by paulf
The capacitor makes no difference to the spark ,it is there for interference suppression.I have ran with and with out it and it made no difference.If you are getting a spark at all then there is not a problem with the Vr sensor or associated wiring.
Paul


Thats what i suspected. Thanks Paul.


Paul (Notts) - 16/4/11 at 06:44 PM

Not kept up to date with your issues so may have already been covered.

1 check that the 12v supply to the megasquirt stays at 12v during cranking and does ot cut out.

2. does megasquirt register an rpm signal during cranking. if not then this needs to be solved or ms will not switch out of crankig mode .

will have a good look at past post when I am sober. just got back from the pub.

Man city are on the way to the FA cup final.


MakeEverything - 16/4/11 at 06:53 PM

quote:
Originally posted by Paul (Notts)
Not kept up to date with your issues so may have already been covered.

1 check that the 12v supply to the megasquirt stays at 12v during cranking and does ot cut out.

2. does megasquirt register an rpm signal during cranking. if not then this needs to be solved or ms will not switch out of crankig mode .

will have a good look at past post when I am sober. just got back from the pub.

Man city are on the way to the FA cup final.


Hi Paul,

Yes it is a permanent feed to the ECU and to EDIS during cranking.

MS doesnt see an RPM signal at all at the moment, which concerns me a little. I should be able to get a decent spark without MS plugged in, so im starting with that first. Then ill deal with the MS issue.


avagolen - 16/4/11 at 07:03 PM

Hi Richard,

With reference to the 12v during cranking, it is very important that you actually measure it while cranking to confirm it.
Do not assume that it will be there during the cranking as volts drop, current flow, etc can create some odd effects.

Len.


MakeEverything - 16/4/11 at 07:11 PM

quote:
Originally posted by avagolen
Hi Richard,

With reference to the 12v during cranking, it is very important that you actually measure it while cranking to confirm it.
Do not assume that it will be there during the cranking as volts drop, current flow, etc can create some odd effects.

Len.


Hi Len,

Yes, Thanks for that. I measured the voltage which drops to 8.5-9Vdc when cranking.


ashg - 16/4/11 at 07:59 PM

i will put money on it being the battery to chassis erath wire or the chassis to engine earth wire. how do i know you ask? had the same problem on my car when it had the pinto.


to cure it i put a new m8 rivnut into the chassis rail then put a 10mm earth from the battery to it then took a second 10mm earth from the same point and bolted it to the engine block.


MakeEverything - 16/4/11 at 08:08 PM

quote:
Originally posted by ashg
i will put money on it being the battery to chassis erath wire or the chassis to engine earth wire. how do i know you ask? had the same problem on my car when it had the pinto.


to cure it i put a new m8 rivnut into the chassis rail then put a 10mm earth from the battery to it then took a second 10mm earth from the same point and bolted it to the engine block.


Ill give that a go, Ta. I did originally think that it was an earth problem, but eliminated it (so i thought) early on. Ill check again.

[Edited on 16-4-11 by MakeEverything]


MakeEverything - 16/4/11 at 09:16 PM

OK, i ran a quick earth directly from the earth bundle to the battery, and i seemed to get more spark, so ill get some 10mm cable and some lugs to replace all the chassis and engine earths. Still not firing though, and it would appear to be sparking at all cylinders so it could be that because the MS isnt seeing an RPM / trigger, its not fuelling.

So, i might have solved the original problem of not sparking (Will know once ive replaced the earth straps), i now need to look at why ive got no signal at MS.