flak monkey
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| posted on 15/4/09 at 07:28 PM |
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Just how unreliable are the VB921s?
Heard that they arent particularly reliable (as in prone to going pop) but as my ecu is already configured with them in are they likely to last until
the end of the year and about 3000miles?
David
Sera
http://www.motosera.com
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brianthemagical
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| posted on 15/4/09 at 07:40 PM |
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MIne have done about 1000miles of use, if they are fitted correctly then they should be fine. The dwell and MS settings need to be as close as
possible. Just buy breakdown cover and a couple of spares.
Just to add, i wouldn't dream of using anything other than wasted spark and a toothed wheel. no problem at all with relability or set up
assuming it's all nicely installed.
[Edited on 15/4/09 by brianthemagical]
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flak monkey
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| posted on 15/4/09 at 07:49 PM |
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quote:
Originally posted by brianthemagical
The dwell and MS settings need to be as close as possible.
Good to hear, but what does this mean?
Sera
http://www.motosera.com
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brianthemagical
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| posted on 15/4/09 at 08:07 PM |
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Basically, it'llbe fine if set up right. Excessive dwell can burn out the driver as it'll be on for too long, connecting the driver
incorrectly to the coil/MS, incorrect triggering point, that kind of thing.
One thing to remeber with MS is that alot of peeps that use them shouldn't, and faults/failures may not nesesarilly be down the components.
I suppose i should add at some point that i'm running MS on my car at the moment. It's a 205 on ITb's. I've done everything
form assembling the ECU to wiring, setup, tuning, nigh on everything, so it is possible. It's been on for about 12 months in it's current
guise and runs better than the std management, with the added bonus of being able to use a laptop on my car. Mine's V3, extra 2 firmware, wasted
spark coilpack which hanndilly is used on later cars so it's bolted into a factory loacation, rather than edis on a bracket. After some setup
troubles it is faultless, but has been improved loads with use as i realise what problems there are and how to fix them, so it wasn't right
first time.
Just keep at it and it'll be mint in the end.
Edited to say that regarding dwell, my was on the std setting for ages on the coil pack with no issues what so ever. As long as you don't chage
it by much then you'll be fine.
[Edited on 15/4/09 by brianthemagical]
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stevebubs
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| posted on 15/4/09 at 08:17 PM |
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I know Bill Shurvinton and few others only use them when necessary - they do try and steer people down the EDIS router.
I believe there is a more robust alternative to the VB921 available now....
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BenTyreman
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| posted on 15/4/09 at 09:53 PM |
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I burnt out a couple of VB921s before I realised there was a problem with my coil pack (the insulation was cracked). I've done 7000 miles on the
current pair, with no problems so far.
As far as I can tell, there is no problem running the 921s at the proper dwell setting. Once the coil has reached saturation any excess dwell causes a
massive amount of heat build-up which kills them very quickly.
All the settings I've seen use somewhere between 2.0ms and 3.0ms.
There is a post on the MS Extra forum talking about VB921 alternatives. Last time I read it they hadn't found anything that exactly replaced it,
but that might have changed now.
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omega 24 v6
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| posted on 15/4/09 at 10:31 PM |
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As already said David the 921's are ok IF the seetings are right.
Mine WERE NOT ( I changed them and fried both drivers) however I now have the bip133 (IIRC) drivers and they are great. As well as current control
they also have thermal overload and reset built in so they don't go pop if you make the settings wrong. Mines cut out in the early days for that
very reason but now my settings are Ok I've had no problems since.
I sympathise with your current problem mate. it took me near 4 months to find my fault ( dry soldered joint in my vr circuit) Now It's going OK
but have still to find out why it won't rev over 4K. I'm hoping it's just the fuel map that's needing fettling but with this
MS thing you never know.
The Ms forums seem to be USA orientated and you wait for ages for a reply. Phil ringwood will reply in a coulpe of days but in the end you're
probably gonna have to sort it out yourself
If it looks wrong it probably is wrong.
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flak monkey
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| posted on 16/4/09 at 06:00 AM |
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I can link a thermocouple up the to 921's to check they arent getting too hot.
Would it be better to start with a dwell on the low side to be safe? I understand the worst that would happen then is that the spark would be weak?
Sera
http://www.motosera.com
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Jenko
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| posted on 16/4/09 at 07:56 AM |
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I managed to burn out a few when installing Megasquirt.....You have to spend time setting dwell......
I've now converted to EDIS which does everything for you and is IMHO a far more robust solution, plus you have the edis limp home mode if
anything happens.....
Many people have used VB921's to good effect, and well done to them. But I would vote edis every time......
MY BLOG - http://westfieldv8.blogspot.co.uk/
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flak monkey
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| posted on 16/4/09 at 08:05 AM |
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I'll have my ecu apart and try and see if I can figure out what needs changing for edis. If its simple I will change the parts and be done with
it. Otherwise I'll give the VB921's a go.
Cheers,
David
Sera
http://www.motosera.com
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corpi
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| posted on 16/4/09 at 08:25 AM |
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There is a replacement for the VB921:
http://shorterlink.com/?P7VNXC
not too expensive, and as said before they protect themselfves when overloaded.
I run MSII whith VB921 driving a coil directly. works so far, but i want to change to the BIP373 to add reliability!
Pieter
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flak monkey
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| posted on 16/4/09 at 08:48 AM |
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quote:
Originally posted by corpi
There is a replacement for the VB921:
http://shorterlink.com/?P7VNXC
not too expensive, and as said before they protect themselfves when overloaded.
I run MSII whith VB921 driving a coil directly. works so far, but i want to change to the BIP373 to add reliability!
Pieter
Are those a drop in replacement for the VB921's? I.e just swap them over and away you go? I know you need to insulate the BIPs as they are non
insulated packages.
Also where are they available from? I dont have time to mess about importing them from the states unfortunately.
David
[Edited on 16/4/09 by flak monkey]
Sera
http://www.motosera.com
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02GF74
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| posted on 16/4/09 at 09:02 AM |
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can you not fit (glue*) a heatsink if it is getting too hot?
* metal loaded epoxy for good themr transmission
something like this http://www.maplin.co.uk/Module.aspx?ModuleNo=30377
I am assuming is it DIL package; I have seen clip on heatsinks like those as well.
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flak monkey
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| posted on 16/4/09 at 09:13 AM |
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quote:
Originally posted by 02GF74
can you not fit (glue*) a heatsink if it is getting too hot?
* metal loaded epoxy for good themr transmission
something like this http://www.maplin.co.uk/Module.aspx?ModuleNo=30377
I am assuming is it DIL package; I have seen clip on heatsinks like those as well.
They are fitted on a heatsink already, the problem is the VB921's dont have any thermal protection and will literally fry themselves if you get
the settings wrong. The BIP have thermal overload protection and simply shut down.
I really dont know whether to go edis or coil drivers....
Sera
http://www.motosera.com
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corpi
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| posted on 16/4/09 at 09:16 AM |
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I've found an adress here in Holland, that seems to have them in stock. At EUR 11.80 more expensive than DIYautotune, but less freight.
If you can't find a source in the UK let me know and I could arrange to buy some, and forward them (at cost plus postage)
let me know if there is interest.
Pieter
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omega 24 v6
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| posted on 16/4/09 at 11:48 AM |
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David i got mine from HERE
Unfortunately out of stock at the moment
I'd thoroughly recommend them ( the drivers and the shop) and yes they are a direct drop in but as you say they need to be insulated. Mine came
with insulators in the kit IIRC
If it looks wrong it probably is wrong.
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corpi
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| posted on 16/4/09 at 11:57 AM |
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omega 24 v6,
did you use the 330ohm resistor? When you read about it, everybody mentions the insulation to the heatsink but none mention the use of the resistor.
What is it's function?
Pieter
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brianthemagical
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| posted on 16/4/09 at 05:27 PM |
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linky
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flak monkey
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| posted on 16/4/09 at 05:40 PM |
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quote:
Originally posted by corpi
omega 24 v6,
did you use the 330ohm resistor? When you read about it, everybody mentions the insulation to the heatsink but none mention the use of the resistor.
What is it's function?
Pieter
Its the resistor fitted between the spark output (neg side of the LED) and pin one of the coil driver.
You only need it if you are fitting coil drivers from scratch.
David
Sera
http://www.motosera.com
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omega 24 v6
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| posted on 16/4/09 at 05:56 PM |
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Yes I used the resistor.
If it looks wrong it probably is wrong.
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flak monkey
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| posted on 17/4/09 at 07:03 AM |
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Right, I bought a pair of BIP373's to replace the VB921's. Just need to check through the circuitry to check the outputs are where I think
they should be, then I will use the internal coil drivers.
If at any point I blow them up, they will be getting chucked out and EDIS fitted!
David
Sera
http://www.motosera.com
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