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MegaSquirt Install on my (Dad's) Defender Pick-Up


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My Dad has a Blue 100inch Defender pick up. The 100inch part is from a Range Rover 3.9efi with autobox and borg warner transfer box.

He bought it as is and we've added some BFG tyres (255/85/16), a CB and a lockable box in the back.

Its a great truck, but the Idle and starting issues of the standard Lucus system were deteriorating until it wouldn't start.

So we decided to have a go at Megasquirt!

After walking back from Nige's shed late one even, with Nige wafting a torch in my general direction and me carrying a whole megasquirt system trying not to gain any injuries while walking down his rather narrow garden path, I was ready to start the install!

More soon!



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I should also add that I had a long chat with Nigel and he talked me through each stage of the build and what all the part were for so I had a good idea of what I was doing when I started fitting it.

So as the HT leads were already off I removed the existing wiring harness and ECU from the main vehicle harness.


I also removed the coil, old idle control valve and all the belts on the front of the engine ready to remove the front pulley.

Once I had removed everything I didn't need I was ready to start adding some of the brackets.

I followed Nigels video here: http://www.youtube.com/watch?v=0GHldV2aKg4 to fit the crank sensor.

Once I had loosened the front pulley bolt and rotated the engine to TDC, I could fit the crank sensor bracket to mark on the pulley where the sensor points too.

Once removed I could then fit the toothed wheel in the correct position.


I then fitted the coil bracket.


One of the stumbling blocks I had was that the existing bolts went through the first half of the coolant pump and threaded into the second half. The bolts that Nige supplied did not have enough thread on them to tighten the coolant pump together and then add a nut on the back to hold the coil pack bracket. When I rang Nige he said 'he hadn't come across this before', so I'll be interested to here how other people's coolant pumps are secured together.


There were still a few bits and pieces to complete before the wiring could be started so we removed the Distributor to modify and fuel tank to fit an in tank fuel pump and get rid of the existing 'in-line' pump.


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Very nice truck. I like a 100".

Yes, nice truck indeed.

I had vapour plans about such a truck. I had more rear overhang in mind for a more balanced appearance, rather than off road clearances.

Good luck with the squirting.

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I should add that I'm a bit behind with this thread so don't be alarmed if it gets built rather quick. I spent most of my 2 weeks off over Christmas fitting the MS kit and a few weekends before!

We modified the new fuel pump by extending the pipe and metal bracket.


And I also modified the distributor to fit one of Nige's blanking caps.

I removed everything out of it.


And chopped it down with a hacksaw ready to bung it in the lathe. I also ran a bit of emery cloth over it to clean it up a bit! The cap is a push fit and I've added a bit of Araldite to stick it on.


All fitted in the engine ready to start the wiring!



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Now seemed a good point to start the wiring.

We removed the inlet manifold to gain better access to the injectors for the wiring, but also to fit the extended breather on the rocker cover which we removed, drilled and tapped and refitted.

We started with the injector wires first and made two sets of 2 into 1 for each bank (slate and red, and green and slate). We adjusted the lengths for each injector accordingly to make the start of our new loom.


We found it easier to fit the connector on the end and then join it to the main loon with a cable tie to achieve the correct spacing and no need to go back and fit a connector nor do you have to label every wire up.

We continued to add in each connector with the corresponding wire and built up the engine harness.

We double and triple checked the wiring for the electronic ignition coils as Nige had suggested!



We added in a connector from the old loom for the crank sensor as outlined in the instructions and we had our very own engine loom. Nige was correct about having enough wire! We could have mounted the ECU on the rear bumper, but we thought it would be sensible to mount it between the seats in a nice little IP rated box.



Don't worry about the two circles, there were speakers there before, but we'll be fitting a fire extinguisher there after the build!


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Now onto the HT leads.

I had never made HT leads before let alone fit them so I was quite looking forward to it! And I'd also bought one of Nige's HT lead crimping tools which worked a treat!

I read both the instructions that Nige had supplied and the ones in the HT lead crimper box to get a good idea of what I was about to do.

I also found a video about the crimper here:

So I started by trimming the outer insulation off using the handy round slot on the side of the tool.


I then bent the serrated edges over as suggested in the instructions.


It's also good practice to do this anyway as if you don't, due to the profile of the crimper the edges sometimes get court as they slide over the metal insert in the crimper when you crimp the terminal. It still crimps, you just meat a little more resistance when you close the vice!

One other advantage of bending the ends over is that you can slide the lead with the folded back inner core into the crimp without needing to hold it or glue it down.


Next I was ready to line it up inside the crimp tool. I made sure that I had the open side of the crimp facing the side with the metal 'W' insert in. You may find just squashing the crimp slightly with a pair of pliers is needed to make fitting it into the crimp that little bit easier.


Once it was in and lined up I added the other half and held it together before putting in the vice.


I closed the vice until it could go no further and achived this!


Using the wonders of silicone spray I fitted the rubber boot and popped it on the spark plug. I repeated this for the other 7 spark plugs trimming them roughly to length remembering I will need a little bit more for the inner core to be bent back on itself.

I was know ready to crimp the other end, so I checked each HT lead as I went, routed it conveniently and crimped it!

Once it was the right length I fitted the rubber boot and plastic clip and trimmed some of the insulation off.

I bent the tabs over on the crimp.


This also aided the fitting and holding of the lead as it held it captive while I lined it up in the crimper.


I used the same method as before for lining it up in the crimper and came out with this!


With the aid of silicone spray (and lots of it!) I slid the boot and plastic clip on and got this.



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The engine bay was pretty much done after I added the new Intake air sensor and reinstalled the air filter.


The fuel tank got reinstalled and plumbed in.

I then threaded the new harness through the hole in the bulkhead to then start the wiring at the other end.

I added the earth wires from the battery to the ECU, the wires for the fuel pump and Lambda sensor too.

I knew where the box was going so I first thought about where everything is going to go in the box and got it fitted.


My Dad chose to make a wooden board to mount everything too and also decided to mount the EDIS upright to conserve space. I nice bit of solid oak was the perfect choice for that! and some plywood to mount everything on.

Once that was done I started by fitting the wires that weren't coming from the engine bay e.g. the wires from the EDIS to the ECU and wires from the fuse box to the relays.

After that it was a question of soldering on all the wires from the engine bay and using the fancy heatshrink connectors that Nige supplied, great bits of kit they were!

I left the heat shrink off the wires for the ECU connector just in case I need to move any of them.

Once they were all done I added a few cable ties to hold all together.

By this time we were very close to starting, so we went through Nige's instructions to make sure we had done everything and checked the wiring on the ECU plug and EDIS plug, checked all the HT leads were in the right place and everything looked pretty good.

So with my new(!) £30 Dell XP laptop I loaded up the software and plugged it in to the ECU.

Fingers crossed we flicked the ignition on.

After swapping out a few dodgy relays the ECU became live and you could hear the fuel pump kick in and all the gauges were reading sensible temperatures.

That was good, so we added some fuel ready to fire it up.

After a bit of cranking, but no firing we found that we needed to swap the wires over for the crank sensor.

But still no firing, Mmmmmm, we thought it maybe low battery voltage so we took the battery out and charged it up ready to have another go in the morning.


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So with a fresh battery we had another go.

It was still cranking, but no signs of bursting or coughing into life, Mmmm.

We took a spark plug out and rested it on the engine and stood well back as I didn't want to get an electric shock!

We had spark! So that proved that the crank sensor was working and the engine was turning over around 150rpm.

Do we have fuel?

We took the return line off and with a few ignition on/off's we thought we would see fuel. No fuel!

So we took the feed pipe off the tank, again ignition on, no fuel.........Then the penny suddenly dropped, what about swapping the wires over for the fuel pump?

Ah, thats better, lots of fuel!!

So after we re plumbed the fuel system back together we were ready for another try.

With the first turn of the key it burst into life!

How happy we all were!

So we let it warm up and the idle came down to 800rpm when fully warmed and it reved up ok.

So the next step was to tape the loom up, fit the heatshrink and do all the wiring tidying.



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  • 2 years later...

Well, over the last 18 months it has been faultless and a hell of a lot better than the original Lucas stuff which is no surprise! We've done a little bit of tuning, but that's about it.

Unfortunately over the last couple of weeks it developed what sounds like a misfire and so we were unable to take it to the Scott Williams Memorial winch challenge which happened last weekend over at West Harptree near Bristol. (My Red one took part and it was a great event!)

So it developed a misfire or what sounded like a misfire, so my Dad checked for spark at all the plugs after disabling the fuel supply. Ah! No spark at two plugs, this was narrowed down to one side of a coil back had packed up (it had cracked and bulged slightly). Once this was replaced (and sparks were checked, now 8 sparks) it was still running lumpy and not as smooth as normal. Also there was lack of power and acceleration if you floored it.

I thought that the map may have mysteriously corrupted itself, so reloaded it, but without any success.

I have spoken with JU (Fridgefreezer on here) and he mentioned fitting a new set of plugs as some of the plugs are a bit black. I fitted the plugs from my Racer, but still with no improvement. 

So now I'm looking for some help and advice for where to look next. I potentially have kit of MS parts to swap out to see what improves with out shedding out loads of money, so that will help too.

The symptoms are:

 - sooted plugs, black

 - running lumpy, not as smooth as usual

 - lack of acceleration and pull

JU mentioned that the coil back could have damaged the EDIS unit. 

Could it be a leaky injector? A dodgy MAF?



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Steve, you can rule out a dodgy MAF as there isn't one :P

Also, you had an obvious fault (burnt out coil) so I'd be surprised if by some great coincidence an injector suddenly started leaking on the same day (and very unlikely all 8 suddenly going faulty). More likely as I said is the coil damaged the EDIS module (if you have a spare EDIS module it's an easy plug-in check).

What readings are you getting on the MS at idle / when driving? Are all the sensor readings sensible & moving as you'd expect?

Are all the plugs going equally black or just some cylinders?

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Too much fuel is only really going to be a few things....

Too much fuel line pressure (fuel pressure reg failed closed)

Coolant temp sender -these fail at -40C so dump millions of extra fuel into the engine needlessly

MAP hose missing (as Quag says)

Electrical short to earth on the injector wire that goes to the ECU

Can't really think of anything else, chaps?


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So we picked up a spare EDIS module today and it didn't change things. Now admittedly it's not a known working unit to me as I have no history with it, so for future reference is it an EDIS 4 I need?! As it's wasted spark right?


Here's a view on start up, all the dials seem to be moving about and on our little run we saw the coolant temp increase to 76 and MAP change too. AFR was moving and so was the ignition.

Surely a failed fuel pressure regulator would result in a burst fuel pipe somewhere?!

Although it sounds ok at idle, it still sounds like it's running slightly lumpy when driving around.


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We've done compressions and we have 125psi across the board, so we can rule out valves not seating and piston rings etc.

I'm going to look at the injectors next. We think one may have failed or is leaking, so I'm going to try and test all 8 at work beings you can get to all 8 once you remove the fuel rail!

Hopefully we'll find something here as it's becoming a little frustrating as we want to use the pick up!


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  • 2 weeks later...

So I took the injectors to work to flow test them and here's what I found!


Yes, one of them wasn't going to do any squirting because of this!


Yes, one of the terminals had completely rusted away or at least rusted through. The other bit was still in the connector!

Injector swapped out for another one I flowed and with a little bit of vasoline in the plugs, it's back to how it is! My Dad's well happy and we'll be at an off road site somewhere soon!



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  • 1 year later...

Another two years of trouble free megasquirting! Been to the usual Seven sisters pilgrimage as well as green laning and playdays.

But last week it seem to boil over on a short trip to the shops. We nursed it back the mile or so and checked it over.

(Two weeks prior to this we had happily driven round seven sisters for two days!)

There was signs of water coming from the cap, but nothing else.

We decided to check the level (which had dropped due to it boiling over) and start it up to see what it would do as it could be a mysterious one off! It warmed up and sure enough it started to boil and the expansion tank cap relieved it's pressure. You could hear the water around the engine crackling and boiling, so we stopped it at that point. So our thoughts were maybe the water pump has failed (due to no flow and boiling over), or there was a blockage (a build up of sludge? although the coolant has been changes in the last 2-3 years, or the expansion tank cap has failed (it was coming out under the cap where I suspect it would and I could hear the whole engine boiling) The cap could had relieved the pressure to early allowing the coolant to boil sooner?

Our plan of action was to inspect the water pump, as there couldn't have been flow! It did sound unlikely, but it was possible, so we drained the coolant and removed the water pump. Sure enough it spins up nicely and the impeller is still attached! Hmm.....so we ran some water through the rad and engine to see if we had flow. The rad came straight out from top to bottom. The engine going in through the top hose and a slow trickle of water later out through the water pump area. Now that all seems good, but I wasn't sure if the thermostat would let any water pass or does it have a small bleed hole as the water did take a moment to come out the other end?

We have thought about removing the thermostat and inspecting and testing it and also replacing the expansion cap, but not done either yet.

This is as far as we have got as we are still puzzled to what might of happened?

We've had no overheating/boiling issues before so it has come as a bit of a surprise.

Any pointers or thought are very much welcome as we've run out.


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