my USB adaptor at fault perhaps....?

beachbuggy61 · Post by **beachbuggy61** » Mon Mar 07, 2011 10:44 am

Hi,

I've looked through the topics and can't really find an answer to my question, hence this post. Apologies if the answer is out there and I just can't find it!

I have my MJLJ all set up on my Baja and it runs sweetly..... at low revs.... so I'm thinking that the default configuration may be off the mark which is understandable. So, I plug in my laptop with a USB adaptor and I get no readings at all. I've checked the device manager and found it's on COM 3 so I changed the configurator settings to read off COM 3 and still nothing. I tried all 20 COM's and all read nothing.

Talking to a mate who has it set up on his beach buggy, he thinks that maybe it's my USB that's the problem.

I don't have a desktop or laptop with a serial port so my only option is the USB.

Is there a particular brand or type that I should ask for at the computer store (I borrowed this one from a guy at work but I guess I'll have to buy one

)?

There is power to the Megajolt unit (green light is on) and although it's not powering properly (probably due to a wrong ignition configuration), it is definitely not in limp mode, so the megajolt is working I guess.

All help and advice greatly appreciated.

Cheers, Marc.

Post by **brentp** » Mon Mar 07, 2011 6:44 pm

Hi Marc,

Aside from testing communications using the software, another way to tell if the Megajolt is 'alive' is to use a timing light to observe changes in ignition advance, as you vary RPM.

Can you verify this while the engine is running?

As for the USB-serial adapter, yes- there can be compatibility issues. An alternative, just for testing purposes, is to take the Megajolt to a different computer- like a desktop machine with a built-in serial port. You may need to power the unit with a 9V battery or equivalent. This way, you can verify the unit can communicate- and provides you an opportunity to load a different ignition map.

We're assuming the engine runs *smoothly*, but with reduced power? If it runs roughly and/or tends to backfire, you may have a plug wiring mixup.

beachbuggy61 · Post by **beachbuggy61** » Mon Mar 07, 2011 8:35 pm

Hi Brent,

Thanks for that. I will check with a timing light to ensure the MJ is working. I'm also going to a computer store today to see abut another USB adaptor.

Will let you know how I go.

Thanks for your prompt reply.

Cheers, Marc.

beachbuggy61 · Post by **beachbuggy61** » Mon Mar 07, 2011 8:37 pm

Also, yes, running smoothly means just down on power. I've never heard the engine run as cleanly as it does down low. Definitely no plug mix-ups!

beachbuggy61 · Post by **beachbuggy61** » Sat Mar 12, 2011 12:51 am

Update...

Thanks for the advice Brent. Checked with a timing light and it was working fine.

BTW, I have never seen such a still timing mark under the timing light!!!!! Amazing how much distributor flutter there was before!

Managed to get an adaptor on eBay for 5 bucks so tried that and it works! Also have one on the way from Autosports but just couldn't wait for the postage to arrive (okay, okay so I'm impatient!) so thought I'd try a local cheapie. Never mind, I'll have a backup now!

Off to tune and map......

Post by **brentp** » Sat Mar 12, 2011 7:30 am

Awesome.

Impressive how rock solid it is, isn't it? We're seeking a 'before' and 'after' video showing the difference in timing stability. Can you still run your engine off of distributor, by chance? If so, let's talk!

beachbuggy61 · Post by **beachbuggy61** » Sat Mar 12, 2011 7:40 am

Hi Brent,

No, sorry. Distributor gone and hole plugged so no dizzy for me any more!

Having all sorts of trouble getting the mapping right though. I seem to get to about 4700 - 5000 and the power drops off

I just can't seem to get the advance curve right. I don't have access to a dyno so it's a painstaking process of reset - drive - get angry - reset again - repeat. I've made another post about advance maps so hopefully someone will have an idea....

Cheers, Marc.