Megajolt

[jayk]

Hello All,

Is anyone using a megajolt on their rover 3.9V8?

I am after a map for both Petrol and LPG, that is known to be good.

I will be running MAP and not TPS.

Rdgs,


John.

[rangeyrover]

Yep

Some links for you, on other boards I know, but they will help you in your quest. If you have a 3.9 Hotwire the installation is quite easy.

You will need an EDIS 8, 2 coil packs, vr sensor, trigger wheel, vr sensor bracket, HT leads, diode arrangement to tell the 14cux the rpm, and a Megajolt.

I would get it running with the EDIS 8 first, then buy a megajolt.



Links

http://www.spondonoffroad.co.uk/Test/up ... andard.odg
http://forums.lr4x4.com/index.php?showtopic=40180
http://www.pirate4x4.com/forum/showthread.php?t=690068


Hope that helps. My reason for using it was to avoid the v8 cutting out near water. It is easy to have 2 seperate ignition maps making it perfect for lpg

http://www.autosportlabs.org/viewtopic.php?t=1738

[jayk]

Hey thanks for the reply rangeyrover. I have actually read quite a few of your posts about megajolt a few forums. You insight has been very helpful so far.

I have taken the plunge and order the Megajolt V4 Kit with MAP sensor, and a rover trigger wheel. Hopefully it will be here within the next week or so. I amlooking forward to settting it up.

I will source some EDIS 8 stuff fromthe states and get that going before I tackle installing the Megajolt.

Does anyone have a ignition MAP for the rover 3.9 petrol or LPG so I have a good MAP to start with. No point trying to reinvent the wheel I say. It would be much appreciated.

rangeyrover, was the zener diode in the ECU signal actually required? I have read somewhere that there is a resistor on the line already that will do the work, is this the case?

Regards,

John.

[rangeyrover]

Technically the zener diode is not required, because as you say, there is an inline resistor protecting the ECU.

The Zener does help to clean up the signal such that no interference can get back to the ECU though, I have always used that cct in all of my installations, with no problems.

So for the cost of the 10p part I would use the zener in the circuit.

RR

I have sold kits to 2 guys with LPG so will be in touch re maps.

[davew]

If you don't have any luck finding a Megajolt map I have a good 3.9 Megasquirt map I can screenshot for you. No LPG though.

[jayk]

Hey Guys,

Thanks very much for the replies. I am still yet to find anyone else with maps they can help me with. So it would be great if you could post a screenshot of your working petrol map.

Hopefully the MJ kit should arive at the end of this week or next and the project can be soon.

John.

[davew]

This one works well...
http://www.yorkshireoffroadclub.net/ima ... fullsize=1

[jayk]

Thanks davew. The map will come in very handy.

I recieved my MJ Kit and triggers wheels in the post yesterday. My EDIS stuff should be on the way from the states aswell.

I am going to see if I can get some free time for soldering the weekend. Wish me luck... the surface mount stuff is small!!!!

If anyone can locate a LPG iginition MAP,it would be appreciated.

Thanks for yout help so far guys.

[jayk]

Ok. I built the kit today and all seems to work ok.

Except I have one question which I am hoping is a stupid one.

If the MJ with MAP sensor is powered up on a bench and connected to my computer. What should the Load be measuring. My unit is reading 100Kpa with no vacuum applied... If I attach a hose and give it a suck the dial goes backward to around towards zero and defaults to 100 with no vacuum.

Is this the correct operation or is the load meant to go from 0 towards 100 when vacuum is appled. Have I stuffed my assembly?

Rdgs John[/img]

[davew]

That's correct, atmospheric pressure is around 100KPa normally, anything below that is a vacuum.

For a normally aspirated engine 100KPa indicates full throttle, at anything less than full throttle the pressure will decrease in the plenum chamber, and will be at it's lowest during overrun.

[chimpboy]

Keep us posted as I'd like to do this at some stage.

[jayk]

Ok. Another quick question.

I understand that the 1N4001 or 1N4004 are suitable diode for the coil to ECU driver.

However all I have been able to find is that a 12 - 18v or 15-18v Zener diode, does the zener have more indentifing number?

Ok.. EDIT that... I found part number BZX85C15 to BZX85C18 for the Zener.



Rgds

John.

[rangeyrover]

Ok. Another quick question.

I understand that the 1N4001 or 1N4004 are suitable diode for the coil to ECU driver.

However all I have been able to find is that a 12 - 18v or 15-18v Zener diode, does the zener have more indentifing number?

Ok.. EDIT that... I found part number BZX85C15 to BZX85C18 for the Zener.



Rgds

John.

The zener value isnt critical. It isnt handling much current. 12-18v should be fine. Bear in mind that there is an inline resistor limiting current.

[jayk]

Well I now have all the kit i need, and I even built a bench test of the megajolt, which was a great success. I had the trigger wheel mounted in a variable speed drill, and the EDIS attached to one coil pack. Everything worked as expected.

I have started to push on, and started on removing the harmonic balancer. However now I am stuck on removing the viscous fan assembly. I have no way(I can think of) to hold the water pump pulley while undoing the viscous fan. There is no way the harmonic balancer will come off without the fan removed, maybe even the radiator.

The thought of taking it to someone to get the trigger wheel put on has crossed my mind. However, I know i will get the usual, why do you want to do that from the rover mechanic.

So i am sort of stuck. Does anyone have any great ideas on how to remove the viscous fan.

John.

[RangingRover]

yep. Use a fan spanner. Which is a spanner 32 or 36mm depending on which fan you have, that you hit the end of with a hammer. You don't hit it sideways though, you hit the end of the spanner in such a way that the force is transmitted straight down through the spanner into the fan, but slightly pushes the spanner in the undo direction.

I've used a normal 32mm spanner on mine (when I had the engine driven fan), and I think I may have even gotten away with a shifter one day. Depends on how much room your fan has behind it.

[red90]

And stick a screwdriver in the pulley to help jam the belt.

Remember it is reverse thread. Clockwise to undo.

[jayk]

Ok.. I wound up drilling a hole in a piece of flat bar. I then bolted it onto the water pump pulley using one of the 3 existing bolts on the face of the pulley. It was surprisingly easy once I had a way of holding the water pump still. I am going to put in thermo fans now the viscous fan is off. I have a thermo switch already, but I eventually want the Megajolt to do the fan switching.

I then took all the belts off and removed the harmonic balancer. That was another item that was difficult to hold while undoing the 6 assembly bolts, I just happened to have an old block with the crank still installed. So I whacked the balancer on there to hold it while I undid the bolts.

The trigger wheel bolted on easily enough, of course it wasn't until it was all back together that it was evident that it was one tooth out. The slots in the trigger wheel made it easy enough to shuffle around.

The bus is now all back together again, running on distributor still, but the trigger wheel and sensor are mounted.

Next.. the wire-up of it all.

[jayk]

I thought it was time I tried putting up some pictures.

Here is the trigger-wheel on the H.balancer


Another angle.


The balancer in the car @ TDC


The missing tooth past the sensor 5 teeth before TDC

[russa]

Thanks Jayk, great photos.

Bit worried about clean that bench is though.

Russ.
5.0ltr Leyland 72 2 door, buggered Luminition.!
Megajolt underway.

[jayk]

Hello,

When I originally posted about the megajolt. I was planning on installing it on the 3.9 Disco. However,now I am installing it on the 3.5 RRC, with the flapper injection. So now I have a question.

Does the Flapper injection ECU require the signal from the -ve on the coil. I can see a negative feed with a resister, but it goes to a relay just under the Air Flow Meter. Does anyone know?

I pulled the negative feed off when the engine was running on the Disco and the RPMs climbed considerably, I figure as the ECU doesn't know what is going on, so it over compensates somehow.

I am yet to pull the negative feed on the 3.5 RRC when it is running, I figured I would ask here first.

Any help would be great.

Thanks...

John,

[jayk]

So today I spent a go few hours roughing in the wiring for the EDIS and Megajolt. I have it roughly installed with vacuum, pip, saw and power going into the cabin for the MJ and the EDIS just has power and the VR sensor. Basically everything but spark.

I plugged the laptop in and took the bus for a quick drive so i could watch the output and see if it was as expected... and it was..


MJ and EDIS roughed in output.

[rangeyrover]

Hello,

When I originally posted about the megajolt. I was planning on installing it on the 3.9 Disco. However,now I am installing it on the 3.5 RRC, with the flapper injection. So now I have a question.

Does the Flapper injection ECU require the signal from the -ve on the coil. I can see a negative feed with a resister, but it goes to a relay just under the Air Flow Meter. Does anyone know?

I pulled the negative feed off when the engine was running on the Disco and the RPMs climbed considerably, I figure as the ECU doesn't know what is going on, so it over compensates somehow.

I am yet to pull the negative feed on the 3.5 RRC when it is running, I figured I would ask here first.

Any help would be great.

Thanks...

John,

I'm surprised the 3.9 ran without the -ve from the coil. The 3.5 flapper also needs the information from the coil, otherwise it cant work out where in the map range it is. Ill experiment with mine tonight 3.9 by pulling it but im pretty sure it wont run without it.
Flapper ecu needs the same information
http://www.extraefi.co.uk/Drawings/PDF_ ... lapper.pdf

Pin 1 I believe

[jayk]

Thanks for the reply.

I found that diagram on the net, and I wasn't entirely sure if the line coming from PIN1 to the coil, was to the -ve or +ve side of the coil, because it appears the same line comes from the ignition switch. Which I assumed was +ve.

So the -ve feed from the coil, goes through the relay on the air flow meter bracket, to the ECU. The relay breaks the feed to the ECU as an anti-dieseling thing. How does the negative feed to the ECU work? Does The negative side of the coil pulse to +ve 12V each time the coil fires?

The disco was running on LPG when I pulled the negative feed, which may help explain why it was still running. Sorry probably should have mentioned that.

I am hoping to get the bus, running on the coil packs this weekend. This is the last piece of black art, I would like to have sorted in my head before wiring it up and turning the key.

Regards,

John.

[91rangie]

I run megajolt on my 3.9 with Hot wire injection.
You have to make the -ve zener diode circuit in order for it run on petrol only no need if it is on LPG.
The -ve is the injector pulse wire for the ecu which tells the ecu to start firing the injectors. You will find that when switching to LPG this wire is disconnected to stop fuel flow while running on LPG
I havent delt with the flapper type injection but would imagine it would need this circuit aswell as the rev counters are run from the alternator not the coil.

[jayk]

I spent this weekend finishing the wiring and making a mount for the coil packs.

The engine started perfecting first turn of the key. When the engine is warm, I have found that i get quite of a log of backfires on LPG when cranking. This has led to a few blown off hoses.

I set the cranking advance to 8 degrees. Which hasn't really stopped the backfires on start up, but it appeared to help. However, this morning I found the car was extremely hard to start, with the crank advance of 8 degrees.

I thought the backfire might be due to too much advance at startup, but it seems that 8 degrees might be too low for a cold start.

I still have the stock coil wired up, with the HT plugged to stop it arcing to the body. This means that I still have the ECU feed coming from the negative of the stock coil. The car seems to run quite well on petrol in this state. And when started it run well and drives well on LPG. Just the backfire when trying to start, that plagues me, as a blown off hose stop the car from starting.

I also built the diode and zener diode circuit for the feed from the coil packs, and i tried running the ECU feed from this, but I found the car ran really rough. I ran the feed from the zener circuit through the stock resistor. Should I leave the stock resistor in place, or am i bringing the feed down too low for the ECU to register it.

In short, what sort of cranking advance should I ran? What is ideal to help cold starts and stop backfires on start up. Or is something else causing backfire at startup? And, do i need the stock resistor in place when running the through the zener diode?

Does anyone have some advice?

Thanks in advance for any help.

John.

[rangeyrover]

I also built the diode and zener diode circuit for the feed from the coil packs, and i tried running the ECU feed from this, but I found the car ran really rough. I ran the feed from the zener circuit through the stock resistor. Should I leave the stock resistor in place, or am i bringing the feed down too low for the ECU to register it.

John.

Basics first John.
Have you got all the diodes the right way round? Have you got the zener the right way round? Insulting I know but do check.

Are there any shorts from one diode to another?
You do NOT have to remove the stock resistor. You can leave out the zener but I never have.

Where is the vacuum pickup from? It should be from the pickup on the back of the plenum NOT on the throttle vacuum pickup.

Finally are you absolutely and positively sure that you have the right coils on the right cylinders? Everyone in my experience has ballsed that up on 1st run. a rv8 will run with some wires right, and it would explain the backfire too.

Cranking start at 8 on mine. Does it start on petrol and edis on its own? It should run solid as a rock at 10 degrees with MJ disconnected.
Good luck
RR

[jayk]

Hello RR.

Thanks for the reply. I will double check the circuit I built and make sure I have all the diodes around the correct way. So I can use both the zener and the stock resister at the same time?

The car runs perfectly when attached to EDIS only. It runs fine on both petrol and gas, at a rock solid 10d BTDC. This is without the feed from the coil packs and using the stock feed from the stock coil.

It is only on start-up that it backfires on LPG. Plus is was hard to cold start. The backfires happen with EDIS only and with MJ attached. I should say backfire. It is normally only one while cranking. This used to happen occasionally on the dizzy, but now happens almost every startup with the EDIS.

I used a multi meter to check what I was getting out from the ECU feed off the coils before I attached it. I can't remember what it was, but I remember thinking it was rather low, something like 11.xx Volts. Does this sound too low?

The car wouldn't be running and idling perfectly if I had wires to the packs the wrong way around would it? It is just start up, on LPG that I get a backfire.

Vacuum is off the back of the plenum.

John.

[rangeyrover]

All of my installations have the zener with the resistor running fine.
I will check the o/p voltage from mine when I get home tonight, I've never checked it.

I would suggest that as you have the dizzy still available that you graph the current set up with a timing light. Do you have a timing tape?
You can then replicate that setup on EDIS. There are many variables in your case because of the LPG which requires more advance. I am presuming that the current dizzy map is optimised for LPG?

What map are you using in the MJ? One for LPG or Petrol?

As regards the ht wires, I personally found it very difficult to tell the difference when I was running on 6 cylinders to 8 at idle. Obvious at speed but not at idle, so I would check them again.

[jayk]

Hello All.

I found that my trigger wheel was 2 degrees out, so I adjusted for this in the MJ. Then I set the cranking advance to 10.

The static of the dizzy was set to 8, and it used to start on gas 99.99 of the time without backfire. On EDIS and MJ, it just doesn't want to start when cold on lpg. I find this a little odd.

Now I have adjusted the offset in the MJ, it only occasionally backfires when starting warm on gas.

The engine idles and revs beautifully, and pulls nicely through the rev range.


I found that with the 4xDiode, 1xZener circuit, the engine ran really rough and sounded like it was missing on petrol. I put a multimeter to the zener output and I was only getting 8 VDC. This sounds too low to me. Did I get the wrong zener? I asked to a 14V, shouldn't I get something like that?

I tested the voltage before the zener and it was reading about 20VDC. Having read that the inline resister already on the ECU input should protect the ECU, i thought I would bite the bullet and try it running the ecu driver without the zener. The car runs nicely on petrol now, all be it it rich, but it always did. I believe my flapper AFM is shagged, which it always was, and probably more so now, after the many backfires I have had.

I have to tidy up the ign lead routing quite a bit. I have to shorten a number of the leads and I do have several cross overs. I relise this could be a contributor to the backfires.

I guess my questions are:

Why would I now find it harder to start cold on gas, then I did with the dizzy?
What voltage should I be feeding the ECU from the zener output?
I am in dangerous territory feeding the ECU without the zener? Is the 20VDC I am seeing at this point too high, or will the resistor be doing the trick?

With the confidence I have gained from playing with the MJ, and a most likely shagged flapper AFM. I am starting to consider going megasquirt
In the mean time, anyone got a ok condition flapper AFM that want to part with....

Rdgs,

John.

[chimpboy]

Would you be willing to resize the image above a little as it causes horizontal scrolling which makes the page hard to read?