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Link Wire-in ECU on classic Beetle


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Hey Everyone,

New to the forum and complete novice when it comes to ECUs and tuning. Have seen however that there is a massive amount of knowledge in this forum so thought I'd ask a few questions...apologies in advance for the long length post.
I'm currently in the process of restoring my first car a 1973 VW Beetle. It's a long way off at the moment, but I'm getting through it steadily. In the last year or so I've become very interested in ECU tuning and would love to learn how to do it. However due to the nature of the beast it's not the sort of thing you can always get into easily as I understand it.
As well as the Beetle I have a 95 MR2 Turbo which I have seen Link offer a plug-in ECU for however with the 3SGTE engine that car has getting harder and harder to come by I'd rather not risk damage by "trying out" tuning on it.
This was where I had the idea to convert my beetle to fuel injection run by a wire-in ECU, as to my mind it seems it would be a much simpler engine to get running and tune myself on the road to learn the basics. (for anyone not familiar it's an aircooled flat 4 1600cc engine, naturally aspirated with 2v per cylinder and a pushrod valve train. Very basic but with alot of aftermarket support for cams, ported heads and so on)
Over the last few years I've had a few engines and setups in the Beetle and have gotten quite proficient at the more traditional tuning techniques for it. Swapping carburetors and tuning them via jet changes whilst reading the spark plugs. Also messing around with the ignition timing via distributor advance spring changes and listening out for pre detonation and setting the timing accordingly. Therefore, having already gained experience tuning this engine on the road, just not via the use of an ECU, I figure I may be able to get myself started with ECU tuning on this car. There is also the added benefit that should I make any error and damage the engine, Beetle engines and parts for them are plentiful and cheap compared to the running gear in my MR2.
So with that out of the way I have a few questions regarding a potential conversion to EFI run with a Link ECU.
1. Is this even a good idea at all or am I being naive thinking I could start to learn ECU tuning by myself? Worth mentioning this isn't something I'm looking to get into doing professionally, just a bit of fun to learn something new alongside other car related projects.
2. For the ECU itself I've been looking at the Monsoon G4X as it's affordable and has the built in map sensor which saves on buying/ wiring a Map. However I'm unsure if the Map sensor is something I will even need. Open to any suggestions or advice on ECU choice.
3. I understand I'll need a variety of other sensors to complete the set up. Firstly as I understand I'd be wise to get an o2/ lambda sensor, I see link make their own to go with their ECUs. Would it be a good idea to get any other sensors like temp sensors or knock sensors.
4. For ignition you can buy wasted spark coil pack kits made specifically for the Beetle. Would I be best just getting one of these for ease or would I be best getting 4 separate coils for each plug?
5. For triggering there are also kits available with a toothed trigger wheel that fits on the crank pulley for the Beetle. Would one of these kits be ok or would I be best buying Links own crank sensor and trigger wheel and fabricating a bracket/ welding those on instead. Is the crank trigger the only trigger signal I'll need or will I need a trigger from the camshaft as well?
6. For injection kits are available for the Beetle with throttle bodys and manifolds with injector ports machined in. These are something I've looked at however some can be fairly expensive so am also open to the idea of fabricating my own fuel system from other parts. Open to suggestions. Also wondering what type of injectors I would need.
7. For the fuel delivery system the car currently only has one fuel line from the tank which runs to a mechanical lift pump on the engine to the carburettor. This of course will need changing to an EFI pump system. Am I best buying a new fuel tank and modifying it to fit an in tank pump and run new fuel lines including a return line. Alternatively could I use an external pump next to the tank and pumb a return in somehow. Another thing I looked at was the use of a "swirl pot" which could house a pump and would be kept full via the existing low pressure pump that feeds the carburettor. However I would then need to find a safe and suitable location for this.
Apologies again for the amount of questions. Not expecting anyone to take up their time to try and answer everything but any small info anyone has would be really really appreciated. 
Excited to hopefully join the Link tuning community,
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  1. Yes, getting the hardware and having a go it is a great way to learn.  Its how we used to all do it before the internet.  It sounds like you have enough interest and tuning fundamentals that you will be successful.  
  2. Yes, the monsoon would be a good option.  Using a MAP sensor is the best way to go for most engines with a single throttle.  If you went to ITB's then you would probably tune using TPS instead and not need the MAP sensor.
  3. Our CAN lambda is good, but quite pricey, maybe overkill for what you need.  There are some 3rd party devices around that work pretty good for less money.  A couple worth considering: 14point7 Spartan2 (connect to analog input) or the AEM X-series (can connect via analog input or CAN bus).  You will need a cyl head temp sensor or oil temp sensor for engine temp, and an air temp sensor either in the intake manifold or if ITB's in the filter.  I wouldnt bother with a knock sensor.  And you will need a TP sensor.  That is about all the esentials.
  4. Either would be fine.  Suggest getting a coil(s) with internal ignitors.  The VW Golf wasted spark one is common and low cost (NGK 2003).  No advantage with COP vs wasted spark with an engine like this.
  5. If there is something available off the shelf then that is a good option.  Preferable a missing tooth type wheel, 36-1 or similar.  Also a cam sensor/distributor sensor would allow sequential fuel (slightly better idle and transient fuel).
  6. Intake and throttle is really up to you.  Single throttle is easier to tune than ITB's.  If single throttle you want the injectors down close to the intake ports, not throttle body injection.  An idle valve is nice to have ion a road car if that is an option on any kits you are looking at.  Years ago the "mexico bettle" manifold kit used to be common for efi, not sure if similar kits are still about. 
  7. A "surge tank" is usually the easiest option for a carb to efi conversion.  You would fit this upfront in the hood area near the tank usually, but no real reason it couldnt go in the engine bay if there is room I guess.  You can get some quite nice ones with the main pump built inside the swirl pot etc.  You will really want an electric lift pump to fill the surgetank, I dont think I would try to use the mech pump.  

Also, I still wouldnt rule out considering a plug-in in the MR2 - there will be a whole lot less engineering involved, and really if you use common sense and take it easy when tuning you are unlikely to hurt anything.  The VW will probably see a nice performace and drivability improvement too though.

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Hey Adam,

Thank you so so much for your long and detailed reply. That's super awesome advise and goes along the lines of what I was hoping to hear. I'll start to gather parts now I've got this information and then once the cars nearly complete I'll get myself an ECU. Should be awesome to drive in and start learning once I have everything wired in. 

Also thanks for the thought on the MR2. I'll definitely consider looking into putting the plug-in onto that as well. Even if not right away will certainly be something I'll do in future.

Thanks again for the kind help,


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