Board logo

megajolt - no spark
bikecarbfred - 12/1/19 at 03:54 PM

the installation was done 2 years ago and worked fine. put another engine in and no spark on plugs

there is 11.85V from centre pin on that goes into main coilpack. to get 12V i touch centre pin with one lead, and the other lead i touch ground which in this case was the car engine.

the only different thing i did was i pulled the wire on vr sensor by mistake and re-wired it. https://imgur.com/kmz5RN0



the wiring is 100% correct from sensor as per link, i checked for continuity also and there is no cut in the wire from sensor to edis.

the sensor is right up to the trigger wheel, hardly any gap. 0.00001. if that's even possible. it's as if touching.

how check for voltage with vr sensor. do i touch pins 10 and 12, against any earth on car like i did on the coil pack connector?

worried because cranking engine with new rings new camshaft.


P.S just checked and all ground connections still good including cable shielding grounds, they all were put at the same point.
[Edited on 12/1/19 by bikecarbfred]

[Edited on 12/1/19 by bikecarbfred]


bikecarbfred - 12/1/19 at 04:13 PM

Just realised something.


The coil pack used to be on a steel bracket that was mounted on the side of the engine.

I decided to spray paint the steel bracket. That should not have anything to do with it should it?

Spraying the bracket and by accident pulling the wire on the VR sensor are the only different things I have done.


David Jenkins - 12/1/19 at 04:29 PM

Try bridging the coil metalwork to the chassis with a wire and try again - at least you will know one way or the other...


bikecarbfred - 12/1/19 at 04:45 PM

looks like the coil pack casing it is getting a ground through the bolts. so that's out of the equation , although i doubt it was going to be that as the ground can also come through the spark plugs.

also checked resistance on vr sensor.
put multimeter on 2000ohms setting and got a reading of 391.



[Edited on 12/1/19 by bikecarbfred]


bikecarbfred - 12/1/19 at 04:59 PM

this time instead of checking resistance on both pins of vr sensor i decide to check the voltage and get 0 volts when cranking.

is this confusion in the megaolt software?


ttalps2000 - 12/1/19 at 05:38 PM

Disconnect the megajolt. The EDIS will run without it at a set 10 degress BTDC. This will then soon find your issue. The wasted spark coil pack has its own earth anyway, so the bracket being earthed will make no difference unless your earth pin goes to the bracket. If the VR sensor is working correctly and the coil pack is too then you will get a spark. If the timing of the trigger wheel is wrong then it wont spark at the correct time. The gap sounds a little close personally to the trigger wheel, but should not stop it triggering.


bikecarbfred - 12/1/19 at 05:56 PM

I took the sensor off and hooked it up to a multimeter and got resistance, i then took one end of the a screwdriver and tapped on the sensor. the resistance changed.
I then check voltage was changing from 0V to 0.3V when I was tapping. but on the trigger wheel it was stuck on 0V when I was measuring the voltage on pin 5 and 6 (edis conector)




i forgot to mention I write and flash a new config to the megajolt, I calibrate the tps then I assume I am good to go to start the engine?
I wonder if it's somet daft like software and I'm messing around with the vr sensor lol


ttalps2000 - 12/1/19 at 05:58 PM

The VR sensor is connected to the EDIS, so get it running without the megajolt first if it was me, removes a lot of potential issues. Sounds like your gap is too little and needs to be increased on the sensor.


bikecarbfred - 12/1/19 at 06:26 PM

disconnected the lead that goes into megajolt and no spark. pulled trigger sensor a little back so there's a minute visble gap aswell. ermm

can someone check the posts above in regards to the vr sensor checking.


i don't know how a coilpack could die sitting in garage for a few years.
was nearly good as new when purchased 4-5 years ago.

gotta be something im missing.

when i crank, i crank for 3 seconds, that's more than enough i hope to get a spark.

[Edited on 12/1/19 by bikecarbfred]


bikecarbfred - 12/1/19 at 06:49 PM

resistance ohms on vr sensor kind of flies all over place when cranking so must be picking up missing tool to fire a spark atleast but no voltage - ive kind figured out you would not get any volt reading on vr by just cranking.


Bigheppy - 12/1/19 at 07:23 PM

Try swopping the crank sensor wires. Its known to stop it sparking if their the wrong way round. I realise you have a wiring diagram but its costs nothing to try.


Jcb198 - 12/1/19 at 07:44 PM

You need a volt meter that reads AC at below 1 volt. Then attach to the vr sensor and crank. You should get about 0.3 volts if the sensor is working. Also check when cranking the voltage at the coil stays above 8.5 v if it stops below it will not spark.


bikecarbfred - 12/1/19 at 08:12 PM

quote:
Originally posted by bikecarbfred
resistance ohms on vr sensor kind of flies all over place when cranking so must be picking up missing tool to fire a spark atleast but no voltage - ive kind figured out you would not get any volt reading on vr by just cranking.


i know it's unusual but im gunna qoute my self lol

i noticed the resistance reading of the vr sensor was flying all over the place when i was cranking.

ttalps2000 mentioned to increase distance. i wonder if this is the issue. never heard of a vr sensor being too close personally.


scudderfish - 12/1/19 at 09:05 PM

quote:
Originally posted by bikecarbfred
never heard of a vr sensor being too close personally.


I destroyed one when it shifted into what is quite an effective circular saw blade at a few thousand RPM


bikecarbfred - 12/1/19 at 09:13 PM

quote:
Originally posted by scudderfish
quote:
Originally posted by bikecarbfred
never heard of a vr sensor being too close personally.


I destroyed one when it shifted into what is quite an effective circular saw blade at a few thousand RPM


mines got a slight grove in it. did your slice to bits?



also im sick of tired today. the fact that i pulled the wire on the vr sensor must mean i must have wired it back incorrect. , screw the diagrams , they must have been wrong in relation to the vr sensor i was sold.

i am not getting a spark so i must swap the wires around on the vr sensor to give me the spark.


snapper - 12/1/19 at 09:48 PM

Check your Megajolt fuse and EDIS fuse, if you have shorted out power feed you may have blown a fuse


bikecarbfred - 12/1/19 at 10:15 PM

both fuse were good, metal wire not snapped in fuse. just noticed in my emails in 2014 i had the same problem when installing megajolt for the first time. no spark. i think i swapped the wires around on the sensor according to some old threads i made. i think my sensorpolarity is not as per diagram and think this what catches me out.

tomorrow i will do this, i need a break. wish me luck

the rate im going i would have "break in" my engine at 100rpm crank speed lol.

hopefully the cylinder walls and new cams have not suffered too much.


Jcb198 - 13/1/19 at 08:47 AM

Is it a 2 wire vr sensor. If it is they generate ac current so not polarity dependant


bikecarbfred - 13/1/19 at 10:10 AM

i think i have found the problem but need confirmation;

the connector that goes into the coil pack to spark the plugs is at 12V when ignition is on.

but when you crank it why does it drop to 0V

i assume this is why it's not sparking.?


scudderfish - 13/1/19 at 10:14 AM

Sounds like your connected to accessories rather than switched 12V. Power to accessories is cut during cranking to make maximum power available to the starter motor.


bikecarbfred - 13/1/19 at 10:47 AM

i am connector to accessories but always was for the years the car was running
there was a row of fuses and i cant remember which one it was now. it kind of drops 12v 6v 2v 0v. i wonder all those years if it was enough to start it.

strange.


bikecarbfred - 13/1/19 at 07:09 PM

got spark.


Slater - 13/1/19 at 08:39 PM

Jolly good


bikecarbfred - 13/1/19 at 09:24 PM

now on to the next problems

don't think this engine building thingy i will attempt again. not worth the hassle. okay maybe one more but that will be it.


scudderfish - 14/1/19 at 06:30 AM

So what was the solution? (for the next person to come this way with the same problem)


bikecarbfred - 14/1/19 at 06:59 AM

We all check that coil pack is getting 12V.

But need to always check if it is getting 12V when you actually crank the engine.

I was getting 12V when ignition turned on leading me to believe wiring was correct.

But when cranking the engine it dropped to 0V.

I had plugged the power cable into the wrong accessory fuse socket.