TESTING Megajolt

damunk · Post by **damunk** » Sat May 31, 2014 5:46 pm

I am taking my car to get carbs on to a garage soon. But I want to make sure all the wiring is correct so the mechanics don't have to mess around.

I've got the trigger wheel and VR sensor.
I want to use my standard ignition system to get to the garage so I wanted to know if I can just test the "sparks" on the megajolt coilpack without it being dangerous.

Can I lay the new HT leads I got, on the engine bay and run megajolt and see if they spark?

Alex B · Post by **Alex B** » Sat May 31, 2014 8:51 pm

Can't tell, but don't you have an old set of plugs lying about? If you connect these to the leads attached to the coilpack and earth them you have the perfect way to test. I used a piece of metal bar with threaded holes that held the plugs. When you attach a timing light to the lead of plug 1 you can even check if advance is correct.

Alex

damunk · Post by **damunk** » Sat May 31, 2014 10:18 pm

Alex B wrote:Can't tell, but don't you have an old set of plugs lying about? If you connect these to the leads attached to the coilpack and earth them you have the perfect way to test. I used a piece of metal bar with threaded holes that held the plugs. When you attach a timing light to the lead of plug 1 you can even check if advance is correct.

Alex

Thanks. I will test it with a spare set. I won't check the advance because I just want to see sparks from each one and that should mean that it is wired up on the electrical side okay?

Also when I start the car obviously with the engine running and the spare set of spark plugs sparking . Is that okay to have 8 plugs sparking? It does not do anything bad?

Alex B · Post by **Alex B** » Sun Jun 01, 2014 8:01 pm

This way worked for me. There aren't many amperes involved so if the electrics of your car are ok it should do fine. Just keep anything that may catch fire away from the plugs

. The sparks are only a gapwidth big, so there isn't too much to it.

Start with the Edis module only, then you can check if the trigger wheel and sensor are aligned correctly. Check this before you send the car to your mechanics, it is best to have this sorted out up front.

Alex

damunk · Post by **damunk** » Sat Jun 07, 2014 1:12 pm

Today was a big fail.

Running standard ignition with megajolt testing by its side with spare set of ht leads & spark plugs.

Don't know where to begin.

1) Start engine = no spark

2) I remove coil pack lead and check middle connector of the three. I test it on the Volt Meter and get 12V when ignition is energized.

3) TPS is wired properly showing 0 - 100% after calibration.

4) I then realise that RPM on megajolt software was always at ZERO I guess indicating it's not getting information from trigger wheel and sensor.

5) So I check the VR Sensor connections at pin 5 & 6. Both show 1.5V on the Volt Meter. I even check the ground is working for the shield cable which it is.

6) I decide to swap them around.

7) I start car with no coilpack and look at the mejajolt software. I see the digital RPM showing 800rpm.

I press the gas pedal to 3000rpm and see that the megajolt is showing 2800rpm.

PROBLEM is the rpm is very erratic!! It is not smooth. It jumps and seemed like it would not go past 4000rpm.
Sometimes it get's stuck and is unstuck when you rev and let the rev drop down to around 1000rpm the megajolt responds well to it. (when it's about to stall)

On a few times it's even shown 0rpm, like it it's lost connection.

9) At this point I decided to quit and NOT test it with the coil pack and spark plugs on as what's the point.

On a side note I am guessing I got the wires right on the VR Sensor if it was showing data this time round?

Alex B · Post by **Alex B** » Sat Jun 07, 2014 3:11 pm

Check if all pins in the Edis- and MJ-connector are pressed home. If there is one that is making marginal contact due to uncorrect installation you may end up like this. When you are sure that all contacts are in order, hook up the coil pack and have the spare spark plugs connected, disconnect the MJ, put the sensor of the strobe light on the lead to cylinder 1 (or 4) and see how the ignition behaves then. If you ave a steady 10 degrees before TDC spark at all rpm's you can omit that from the faulties list. Then it is time to check everything that is MJ connected.

Alex

damunk · Post by **damunk** » Sat Jun 07, 2014 3:29 pm

Alex B wrote:Check if all pins in the Edis- and MJ-connector are pressed home. If there is one that is making marginal contact due to uncorrect installation you may end up like this. When you are sure that all contacts are in order, hook up the coil pack and have the spare spark plugs connected, disconnect the MJ, put the sensor of the strobe light on the lead to cylinder 1 (or 4) and see how the ignition behaves then. If you ave a steady 10 degrees before TDC spark at all rpm's you can omit that from the faulties list. Then it is time to check everything that is MJ connected.

Alex

I don't have strobe light. Can I just do what you said about megajolt disconnected and just try all 4 spark plugs and see if they are buzzing on idle with just edis? Would that show me that megajolt wiring is at faul tand not edis? I will check EDIS wire/pins.

Alex B · Post by **Alex B** » Sat Jun 07, 2014 10:48 pm

By disconnecting the MJ you can at least see if the plugs are firing using the Edis-module only. However, you can't see if they are firing at the correct moment or that they are firing consistently. In addition you can't see if the trigger wheel is set correctly. For sorting out these basics you need a strobe light.

Speaking of the trigger wheel, how much is the gap between the teeth of the trigger wheel and the VR sensor?

Alex

damunk · Post by **damunk** » Sun Jun 08, 2014 8:12 am

Morning Alex,

1mm , maybe even less sometimes.Can see like a scratch on the plastic so it must be very close.
It is maybe 1mm off centre but pretty much looks spot on.

And the magnet is quite good on the sensor. I think I should do the resistance test on the sensor and the coilpack maybe.

damunk · Post by **damunk** » Sun Jun 08, 2014 8:24 am

Just tested the VR sensor on the multimeter. When you put it on the "continuity" setting on the multimeter.
It shows nothing when trigger wheel is not moving.

When you get the trigger wheel spinning the reading is 450.

And when you press gas pedal the multimeter sounds like it is revving up and down (electrical noise) in relation to the gas pedal.

I did not do it too much because don't want to damage anything.#

The EDIS connector pins 10 & 12 seem linked on the the connector when the coilpack is connected.
And there is stable 12V to the coilpack. Why won't the plugs spark.

Is there a way to test the coilpack it self using a multimeter?

Alex B · Post by **Alex B** » Sun Jun 08, 2014 10:34 pm

Is the polarity of the sensor the right way around? Pin 6 of the Edis connector must be connected to the left hand spade of the sensor, pin 5 to the right hand one. Left and right is defined with the back of the sensor pointing downward and the bolt hole to the right. I don't know about how to test a coil pack, but maybe Brent can tell more about this.

Are you sure that there is no short somewhere between the Edis connector and the connector to the sensor?

Alex

Post by **brentp** » Sun Jun 08, 2014 11:37 pm

Echoing Alex's suggestion - the most common no-spark cause is reversed VR sensor. Check that out and see if you get a spark!

Definitely keep us posted on your findings.

damunk · Post by **damunk** » Sun Jun 15, 2014 12:31 pm

I'm not trying for any spark. I just want to see the rpm moving on the megajolt software.
I've attached pictures of the setup. I am using electrical plastic connecters like on the pic on all the wires.

The shield on the VR sensor has been checked and is ground.
I have swapped VR sensor cables back and forth several times.

The PIP/SAW cable pass the continuity test on volt meter. It passed at the electrical connector and as the EDIS end too.

P.S TPS is unconnected.

The VR sensor cable is shielded right up to connections. Cable length just over 2 metres.

I spent two hours this morning and "fail". I just saw the RPM signal flicker to 500rpm to 700rpm for a second or two then was dead after that.

Is the gap between the sensor to the wheel to small? It's very close. The pulley it is attached on is 5-6mm away from the sensor. Maybe it is detecting metal all the time? I doubt it though.

Alex B · Post by **Alex B** » Sun Jun 15, 2014 3:22 pm

You can try whatever you like, but as long as you are not doing the one and only test that shows if your basics are ok you are barking up the wrong tree. So disconnect the MJ, hook up a set of earthed plugs to the coil pack, start the engine and see if you get sparks. If that works you can move on, but not before you have this fully functioning. Is it 100% sure the Vr sensor is connected the right way around? The VR sensor looks ok. The chance that it is constantly sensing metal is next to nil. There are people who have used very fine toothed 72-2 trigger wheels inside the dizzy without a problem. 6mm distance to the pulley is more than enough for getting a good signal.

Alex

damunk · Post by **damunk** » Sun Jun 15, 2014 5:36 pm

Okay I'll do that test making sure I ground the spare set of plugs.