Megasquirt DIYPNP Rework

Last week Josh asked me to help him update the firmware on his DIYPNP Megasquirt ECU, he also needed a base map loaded. So he posted it from Melbourne to Brisbane and I got it early this week.

Josh purchased the ECU second hand off the forums, was told it was working (and I don't doubt that it was) but the surprises came when I opened up the case for a closer look... This is what I found:

  • at least half of the solder joints throughout the board were beyond terrible
  • about a dozen pins/legs had no solder at all
  • the ends of wires were snapping as I was de-soldering
  • a handful of lengthened wires which weren't heat-shrinked
  • tape had fallen off one of the lengthened wires and fully exposed the connection against the metal case
  • loose solder and component pins on the underside, could have easily causes short circuits
  • component pins bent towards each other, more possibility of short circuits

Even if the ECU was working fine, I wouldn't be surprised it failed very quickly in a car environment (heat and vibrations).

So I fully stripped all the wiring off the board, re-soldered every joint, cleaned/removed all the flux, re-wired the connector board, updated firmware and loaded a base map.

Below are some before and after photos.

The wiring was a huge mess, lengthened wires and a lot of fatigued joints which eventually resulted in snapped connections. In the center of the photo you can see the joint that was exposed because tape fell off.

Was difficult to take a clear photo showing the bad solder joints. Looked like a lot of cold joints and not enough solder was used. Quite a bit of flux too.

The wires that snapped clean...

These next photos were taken after I re-worked the ECU.

Re-soldered and board cleaned up to remove all the flux.

The pins on the Microsquirt Module re-soldered and cleaned up.

New jumper wires installed.

My preference is to have the jumper wires on the component side because it places less strain on the wires, helps reduce any fatigue. It also allows easy view of the connections without removing the entire circuit board.


ECU Mounting Revisited

So my first attempt for the ECU mount was a failure, it sucked and was messy looking. This next mount attempt is so simple, not sure why I didn't think of it first. Checkout the photos below.

Used my spare dash to plan my bracket, much easier when flipped upside down.

Had some some left over angle aluminium, perfect for the task at hand.

Quickly positioned to make sure it clears everything.

Stickered my ECU because it's so awesome.

Marked all the holes and drilled everything.

Double checking that all the holes lined up.

Done! Very very happy how it turned out, the bracket is strong and holds it at a good position. The glove box closes up fine, still emptied out so no real use but it'll be locked up anyway.


ECU Mounting


I've been dreading this part of the build, was never sure how I would do it and make it neat. But everything is coming together now and so I had to do something.

Because my custom fuse/relay panel sits where the ECU normally goes, I've had to install the ECU in the glove box. It's not a bad spot to put it, just my solution isn't "clean" for my liking.

I had to remove all the internal sides of the glove box, gives much more room for the harness to hook up. I'll also make a short serial cable "pig-tail" so I can hook up the USB connection.

All the studs were epoxied into place, not very clean and not sure if it'll be strong enough. So I might go over everything with some fibreglass, any thoughts?

Test fit was good too, but I'll let it cure overnight before I tighten up the nuts.

I also decided to use the stock tombstone, goes much better with the rest of my interior. So the KG Works tombstone will be up for sale soon.


ITB Build – Part 10

Update time! Head isn't finished yet so I've been doing a few odd jobs here and there.

One thing I did was start on the brake prop valve relocation. It's not necessary but does give me extra space for the velocity stacks, might be able to increase it's length later down the track too. So I picked up some angle aluminium plate for $5 and started cutting that up.

Cost me $5, pretty awesome deal I thought.

Measure twice, cut once. Came out exactly how I wanted, the prop valve will than be mounted just above the brake booster. I'll get someone to make the hard lines when engine is out.

Here is the capacitor used for the COPs install, it's needed because the battery is in the boot and can cause voltage drops when the coils fire. The capacitor helps by storing a reserve of power and eliminates any voltage drop. Well that's what I think it does =P

Terminated wiring for the AFR gauge, I used Deutsch connectors and braided sleeving.

Ordered these velocity stack booties from Outerwears, quality seems good but I'm not 100% sure they will provide enough filtering. So might experiment with some foam as well.


ITB Build – Part 6

This is a going to be a big-ish update, lots of photos, so please click through to see the rest of the post.

I spent the last couple of days building my custom fuse/relay panel. I've been looking forward to this part of the build 😀

Read more after the break...


Wiring Update

Small update... some wiring parts arrived and picked up a white board to help me scribble down wiring stuff. It's been pretty handy 😀

According to the MegaSquirt manual, it's a pretty good idea to shield the TPS and trigger wires. So have been on the search for a flexible 2-core shielded cable, ended up deciding on a microphone cable from JayCar (part no. WB1530).

Terminated the shielding into it's own BLACK wire, this will grounded at the ECU end and left floating on the sensor end. The BLUE wire will be used for sensor return and the WHITE for sensor ground. The +5V/+12V wire will be run externally to the shield.

My awesome PURPLE (and grey) Deutsch connectors, all solid terminals too.

This is the relay block I'll be using, it's all modular so you can expand if needed.


Build Update

Not much has been happening but some updates for the build so far.

I received my first batch of Brake Cylinder Braces, so took some photos of what it looks like installed. It's too hard to take photos of the install, so will be doing it on a bare chassis in a few weeks.

Excuse my dirty engine bay.

I've also decided to ditch the old style CAS and go with dedicated crank and cam angle sensors. They're used in later model BP4W engines as well as NB6 engines.

Started my ECU harness too. Re-used the ECU connectors and just de-pinned the terminals so I could solder new wires on. Was a tedious process but well worth it, sensors/injectors/coils connectors will be installed later.

mmmm so fresh so clean.

Cleaned up all the connectors that I plan to re-use, de-pinned and bought new rubber seals.

Picked up this cool passenger foot well plate from MX-5 Plus. No idea what brand it is, but it looks useful as it'll give me more space for the MegaSquirt and fuse/relay panel.

Made a decision to get rid of the of standard coil/ignitors and go with the very popular "Toyota COPs". Coil-On-Plugs provide a much better spark as well as giving me sequential spark with the MegaSquirt.


MegaSquirt DIYPNP ECU Build

I've been slowly building my MegaSquirt DIYPNP ECU, just wanted to take my time so I don't screw anything up. I have configured to be run on a standard engine with MAF removed, just so I can learn how to tune the basemap. This means standard narrow-band O2 sensor, stock TPS, etc...

All instructions can be found in the links below:

Build photos after the break =)

Read more after the break...



Ordered my ECU from last week and it arrived today, will start building it ASAP and get it running on the stock engine. Should be able to get some practise tuning the ECU before I get time to install the ITB setup.

The DIYPNP ECU is based on the MegaSquirt Micro Module V2.2, doesn't have as many features as the MS3 but still provides a lot of tuneability and options. Definitely more then enough for a ITB intake setup.

Some quick photos before I start assembling.

Unboxing my new toy =)

The MegaSquirt Micro Module V2.2


Wiring Harness

This weekend we tackled the wiring harness.

The MX-5's engine and body wiring is pretty much one single harness, a huge pain in the ass if you just want to remove the ECU and engine harness. While the harness was out we decided to remove all unnecessary wiring, doesn't have to be done but sure makes for a neater harness. Was a big task ahead of us...

Started off by removing any clips and disconnecting the harness, removing the after-market alarm/immobiliser, and then the blower/heater/air-con boxes.

Read more after the break...