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Posted by: JORACER#40 Jun 14 2024, 03:02 PM

Nathan on YouTube Barefoot Garage Jax converted his D-jet to modern EFI using Haltech 550 and hoping Nathan or someone who knows him would message me so I could ask Nathan a few questions.
I am very impressed with Haltech they been very informative and prompt but this is not a common conversion for them.
I am using a variety of sensors manufactures most from The Dub Shop that not standard for Haltech but will work as long I know how to implement each into the tune.
Just trying not to make the same mistakes and be back on the road sooner than later.

This has became necessary due to my D-Jet started failing and trying to get new or remanufactured parts is next to or imposable.

Posted by: ClayPerrine Jun 15 2024, 05:38 AM

Replacing the D-Jet injection with any modern, aftermarket injection system will require replacing some hard parts. You will need new injectors, the impedance on the D-Jet injectors is not correct for modern injection. You will also need to replace the circuit board on the throttle body with a TPS. And you won't be able to use the stock harness, you will need to make your own our buy one ready made.

The CHT and the air temp sender will have to be replaced. The stock sensor for a 3.2 Carrera/964/993 works well in a 914 with modern injection and is a bolt in on a 914/4 head.

If you wire it correctly, you can use the stock relays on the relay board for the ECU and fuel pump relays.

The rest is just wiring.

Posted by: rick 918-S Jun 15 2024, 09:27 AM

Got a link to the YouTube?

Posted by: technicalninja Jun 15 2024, 09:50 AM

Critical to have a tuning shop close that will work with what you have...

A buddy of mine put a "Hydra" into a MSM Miata which used to be sold by Flyin Miata.

Flyin Miata offered "lifetime" support which they have provided AWESOMELY!

The problem was finding a tuner with a chassis dyno that could work with the Hydra.

One shop in Dallas, it was crappy, and the tuner did the most basic of tunes for the sum of 1K!

Because of the lack of folks that tune the Hydra it's VALUELESS on the Forums.

I have purchased my friends Miata with a popped motor (the Hydra screwed up and ran stupid lean which KILLED the engine). I will throw the Hydra into the round file and replace it with a DIY Megasquirt.

Had it been Megasquirt from the get-go, the engine would not be dead, and I would not own the car...

In my case the Hydra was a GOOD DEAL!

There are three shops at MSR (Motorsports Ranch) 10 miles away that can tune Megasquirts...

Good ones!

Make sure whatever unit you get can be tuned by a shop you would want your car to go to.

Most of the base units are very similar. The DIY unit that is equal to the 550 is what is called a "micro-squirt"

https://www.diyautotune.com/shop/megasquirt-assembled/microsquirt/

Don't buy one until you have verified the shop that will end up doing the final tuning it...

Posted by: technicalninja Jun 15 2024, 10:14 AM

I believe PMB is now installing the Holley version of the base controllers and multiple folks have reported extremely EASY base tuning.

I have no experience with the Holleys but that MIGHT be the easy button.

Posted by: Craigers17 Jun 15 2024, 10:58 AM

Part 1 of, I believe, 8 parts:

https://www.youtube.com/watch?v=lgaWYIsx8F0

Pretty sure he did use the same injectors, but he had to choose a specific Haltech ELITE ecu that was compatible with the old injectors.

Posted by: JamesM Jun 15 2024, 12:18 PM

What parts you need to replace is entirely dependent on the ECU you use and your creativity/skill.

The first Megasquirt conversion I did on a 914, 20 or so years ago now I replaced nothing but the ECU and did it for less than $200. Even kept the stock d-jet wiring harness. Wouldn't recommend that route to anyone though as you need to be borderline insane to attempt that today with the other available options available now.




This was actually part of the reason I started working with Megasquirt 20 years ago. Oddly the ability to keep d-jet going today is actually better than it was then but there are SO many other advantages to going with modern EFI its hardly worth mentioning.

I think the most important thing to bring up if you are going to attempt a modern EFI conversion is the learning curve. There is a LOT of information to take in and I have seen a lot of people do things incorrectly or just outright fail due to not having a good understanding of what they are attempting. The hardware/wiring portion of the build is actually the easiest part, make it through that and you have all the software configuration and tuning. Proper tuning being probably the most difficult part and at the same time the most critical given the nature of air cooled engines. Air cooled engines like to nuke themselves with a bad tune. Follow any of the tuning information on youtube based on water-cooled engines and you are at risk of nuking your engine as well.

Im not trying to say don't attempt it if you are not already an expert, the experience alone is an amazing learning experience, just brace yourself for some bumps in the road and a TON of information.

The Holley systems have been getting popular lately as they are a bit more user friendly and maybe more importantly have manufacture support where as with something like Megasuirt its just you and the internet. One of the reasons they are so popular is the onboard autotune feature, which I think can be helpful but also think people rely on it to heavily/put to much faith in it as autotune as how good it is depends on how it is used and the quality of the target data it was setup for.

Haltech has been done but less frequently than Megasquirt or Holley so you may not find ECU specific information as readily however the underlying concepts are the same for any modern EFI build.

Posted by: technicalninja Jun 15 2024, 12:42 PM

You did it the HARD way!

The first Megasquirts were kits!

You got some printed circuit boards and multiple bags of electronic goodies and got to solder that stuff together!

Yep, you have to be an electronics Geek for that stuff...

The link I provided is the best supplier of assembled megasquirts I am aware of.

The MS3X I ordered ONLY fits MSM miatas and you plug the original mazda wiring harness into it.

The MS3Xs have autotune as well.

I am in agreement with JamesM as to the accuracy of ANY autotune software.

IMO getting it really right requires a trip to the dyno with a Wizard familiar with your brand of poison...

Posted by: JORACER#40 Jun 15 2024, 01:54 PM

I have either purchased or know what components I will be purchasing. Thanks to the Dub Shop, Haltech and Jax Videos. I was hoping to talk to Nathan about the nuances of each custom sensor and how to integrate them into the tune. Also idle control valve was not covered in the Videos.
I chose the Haltech because it will run stock injectors peak and hold. The D-jet was a great system in its day. Since i am using the stock throttle body and injectors the main reasons for using modern EFI is reliability and cleaner emissions due to closed loop and better processing.

Posted by: Artfrombama Jun 15 2024, 06:43 PM

Fascinating subject, thank you for posting.
Updates appreciated!