resest problem solved :-)

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Kev
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resest problem solved :-)

Post by Kev »

given the number of posts on this issue I thought I'd start a new thread on what cured mine.

Rover V8, 4 coil lost spark, 60-2 trigger with Bosch VR sensor.

I had multiple and consistent reset issues on low revs, below about 1500 rpm and also consistenlty when I just tweaked the throttle at tickover.

My cure was fitting a 25uF capacitor on the +12V supply and earth, to the coils right on the +ve connector to the coil.

My earths are all connected to one point apart from the coil earth which is connected to the engine heads and I have multiple earths connecting the engine to the frame.

I've driven my car twice now and left it ticking over for 20 minutes and had zero resets :D :D :D :D I would have expected at least 60 resets during this period so I think I can say pretty comfortably it's cured.

Kev
mkehler
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Post by mkehler »

Why a 25uF as opposed to a different size? I'll definitly try it this weekend to solve my own reset issues, but I'd rather know the theory than simply to blindly follow...who knows, maybe I can figure the next issue out on my own :)

thanks
Matt
Kev
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Post by Kev »

I was advised 25uF is the size Ford use to decouple their coil pack. I hope yours is the same issue and this cures it.

Kev
PSIG
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Re: resest problem solved :-)

Post by PSIG »

Kev wrote:... My cure was fitting a 25uF capacitor on the +12V supply and earth, to the coils right on the +ve connector to the coil. ...
That makes perfect sense as many factory coils (such as the Ford EDIS system) have a ~25uF capacitor on the coil (+) feed. They are usually attached to the coil mounting bracket and are commonly called Radio or EMI suppressors. Good call!
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Post by mkehler »

I assume it won't matter where they are placed? either close to the coil, or close to the megasquirt? I'd rather put them on the MS end, instead of ripping apart my nice factory shielded cable with the factory eyelets right at the coil.

thanks guys!
Matt
Kev
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Post by Kev »

mkehler wrote:I assume it won't matter where they are placed? either close to the coil, or close to the megasquirt? I'd rather put them on the MS end, instead of ripping apart my nice factory shielded cable with the factory eyelets right at the coil.

thanks guys!
Matt
If the theory is correct and they are decoupling the supply from reverse spikes then it needs to be as close as possible to the coil and not at the MS end. Can't you just connect across the coil+ve to ground without breaking into your cable?
Sorry I don't know your background so excuse me if this is obvious but be aware that you connect the cap from +ve to ground, it doesn't go in series with anything. Also the cap should probably be non-polar ie not electrolytic.

Kev
Heribert
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FORD EDIS caps

Post by Heribert »

Agree with Kev regarding placing and type of cap . As close on the + fed to the coil as possible and a very shorth earth lead is the way to go.
Ford has it abt 15 "wire"cm away from the coilpack +contact and earth is bolted directly to chassis ( at least in the three EDIS engine looms I just dissected to get hold of the shielded VR cable with VR contact)
And on all these three EDIS 8 kits the cap at each coil was FORD number
F6AF 18801-AA , measured to be 0,25 µF . Probably metal polyester type .
The size makes sense in order to reduce RFI , a 0,25µF cap has lower impedance in the high-frequency spectrum than a 25 µF electrolytic.

So for RFI and reset woes , I believe a 0,1 to 0,5 µF MP cap at each coilpack plus to ground is the right solution.

Heribert
daxtojeiro
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Post by daxtojeiro »

Hi all,
well I tried the resistive plugs on a car I was having a nightmare to cure the resets on and it has cured that, but then Kev did the same and it didnt cure it for him so I started looking in to it a bit further and as you say, Ford put the cap on their coil packs, I actually found it on a Megajolt diagram, so it looks like its cured Kev's, so hopefully a good earth, resistive plugs and a 25uF cap (dont think an electrolitic is suitable) on the +12V to the coils and to ground could cure a lot of these problems,
Phil
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Post by 65looter »

daxtojeiro wrote: a 25uF cap (dont think an electrolitic is suitable) on the +12V to the coils and to ground
Could you point me to one, I looked on the Maplin website but they have so many different ones :(, cheers
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Post by jsmcortina »

Go to a scrap yard and get the one Ford had made. They are attached to the coilpack mounting bracket and are a square plastic box.

James
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65looter
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Post by 65looter »

James, I got a mapling 10 min walk from where I live, for hte scrapyard.... no idea where is the closest one, and probably wont have it :(
I thought i could get one from Maplin (a similar one), other wise I order a brand new from the Us.
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Post by jsmcortina »

Go to a Ford dealers then. Escorts, Fiestas, Mondeos all have them. Likely newer stuff too.
A part from Maplin can likely be made to work but it doesn't have bolt holes and connectors to automotive standards for underbonnet use.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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Kev
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Post by Kev »

65looter wrote:
daxtojeiro wrote: a 25uF cap (dont think an electrolitic is suitable) on the +12V to the coils and to ground
Could you point me to one, I looked on the Maplin website but they have so many different ones :(, cheers

The only suitable Maplins ones I could find were either 20uF or 30UF motor run capacitors, a bit ott for this application. Rapid electronics only have one also ott http://www.rapidonline.com/productinfo. ... leno=62525
http://www.falcon-acoustics.co.uk/ have a 25uF 400v one at 4.99.
http://rswww.com/cgi-bin/bv/rswww/searc ... cheID=ukie
https://secure.wilmslow-audio.co.uk/aca ... CR_49.html looks ok but typical of this firm very expensive.

Any of the 25uF listed should be OK depending on where you can order from. Alternatively scrap yard will be cheaper :idea:

Kev
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