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shconer
Samba Member
Joined: August 27, 2014
Posts: 6
Location: Canada
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 Posted: Wed Sep 03, 2014 12:34 am Post subject: BOSCH D-Jetronic Megasquirt Adapter |
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I have built a prototype board that adapts the factory Bosch D-Jetronic card edge connector in my 1969 Squareback to the DB-37 connector of my Megasquirt 2. Also I retrofitted the factory pressure sensor with a modern sensor inside. With some small modifications to the Megasquirt board to accommodate the external MAP sensor. I have created a plug and play system that works with the factory harness and does not require any further modifications or additions. Alternately you could instead connect the standard Megasquirt onboard MAP sensor with a hose to the manifold and lose the factory appearance. I have done some testing with the prototype board and I am in the final stages of developing the final version. Before I ordered PCBs and components I thought I would see if there is any interest out there for something like this. The final PCB is designed to mount inside of the factory case with room for the Megasquirt. An assembled adapter would cost approximately $80 CAD. This could be a cheaper solution for someone with a malfunctioning D-Jet ECU or a dual carb conversion. Please note that fuel acceleration enrichment is based on the MAP sensor only as the factory system does not have a TPS sensor. The factory idle control system still controls idle. This is a fuel only set up and the factory distributor and ignition is used. Also there is no provision for EGO feedback, it is a open loop system. This adapter works with MS1 or MS2 V3.0/3.52.
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Intrinsic
Samba Member
Joined: November 16, 2011
Posts: 262
Location: Clearwater, FL
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| Posted: Wed Sep 03, 2014 5:13 am Post subject: |
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| Great work, I have been speculating about such a modification to the MPS for some time. This should make the MS more appealing to folks who want to preserve the original look. |
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Bobnotch
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Joined: July 06, 2003
Posts: 22431
Location: Kimball, Mi
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| Posted: Wed Sep 03, 2014 9:05 am Post subject: Re: BOSCH D-Jetronic Megasquirt Adapter |
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| shconer wrote: |
| I have built a prototype board that adapts the factory Bosch D-Jetronic card edge connector in my 1969 Squareback to the DB-37 connector of my Megasquirt 2. Also I retrofitted the factory pressure sensor with a modern sensor inside. With some small modifications to the Megasquirt board to accommodate the external MAP sensor. I have created a plug and play system that works with the factory harness and does not require any further modifications or additions. Alternately you could instead connect the standard Megasquirt onboard MAP sensor with a hose to the manifold and lose the factory appearance. I have done some testing with the prototype board and I am in the final stages of developing the final version. Before I ordered PCBs and components I thought I would see if there is any interest out there for something like this. The final PCB is designed to mount inside of the factory case with room for the Megasquirt. An assembled adapter would cost approximately $80 CAD. This could be a cheaper solution for someone with a malfunctioning D-Jet ECU or a dual carb conversion. Please note that fuel acceleration enrichment is based on the MAP sensor only as the factory system does not have a TPS sensor. The factory idle control system still controls idle. This is a fuel only set up and the factory distributor and ignition is used. Also there is no provision for EGO feedback, it is a open loop system. This adapter works with MS1 or MS2 V3.0/3.52. |
That's a nice solution. Just so you know, a better version to have set up might have been the 70-71 version, as those DO use a TPS sensor. 
Plus the 70-71 version seems to have the most issues, mainly due the the MPS (different from the 69 version). Just a thought. 
_________________
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71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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supersuk
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Joined: December 20, 2010
Posts: 958
Location: Honolulu, Hawaii
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shconer
Samba Member
Joined: August 27, 2014
Posts: 6
Location: Canada
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| Posted: Wed Sep 03, 2014 3:35 pm Post subject: |
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| Looks like the only differences between the early and late models is the addition of position to the throttle switch and omission of the pressure switch. Shouldn't be a problem making the adapter compatible with all years as the pressure switch is obviously not used with the Megasquirt anyway. This would probably make it compatible with all the fuel injected 914 models as well. |
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Bobnotch
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Joined: July 06, 2003
Posts: 22431
Location: Kimball, Mi
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| Posted: Wed Sep 03, 2014 4:45 pm Post subject: |
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| shconer wrote: |
| Looks like the only differences between the early and late models is the addition of position to the throttle switch and omission of the pressure switch. Shouldn't be a problem making the adapter compatible with all years as the pressure switch is obviously not used with the Megasquirt anyway. This would probably make it compatible with all the fuel injected 914 models as well. |
This was kind of the point I was trying to make this morning, in that the later version D-jet was used on more models, and this "retro-fit kit" could be applied to more vehicles than just the early FI cars.
I think Joe said that he made up a kit that reversed the 71 style D-jet harness, to be used with the 68-69 components. He said it wasn't hard to do, and was only 4 or 5 wires different. But then, he also said his car seemed more stabile using the 68-69 D-jet FI versus his 71 D-jet set up.
But, the point that the MS could be used with pre-existing D-jet components sounds very welcoming. 
_________________
Bob 65 Notch S with Sunroof
71 Notch ...aka Krunchy; build pics here;
http://www.thesamba.com/vw/forum/viewtopic.php?t=249390 -been busy working
64 T-34 Ghia...aka Wolfie, under construction... http://www.thesamba.com/vw/forum/viewtopic.php?t=412120
| Tram wrote: |
| "Friends are God's way of apologizing for relatives." |
| Tram wrote: |
| People keep confusing "restored" and "restroyed". |
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Nate M.
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Joined: August 11, 2003
Posts: 1306
Location: Anacortes, WA U.S.A.
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| Posted: Wed Sep 03, 2014 10:27 pm Post subject: |
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Very cool!! You really should post this on the 914world site in the Garage forum. I think you would find quite a few 914 owners who would like this so they could retain the factory appearance while still having more performance.
Nice work!!
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Nate M.
Squarsche build
Heavy Metal Affliction feature
For heaven's sake, put a type4 and a Porsche 5-speed in there. . . It's the right thing to do!! |
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shconer
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Joined: August 27, 2014
Posts: 6
Location: Canada
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| Posted: Thu Sep 04, 2014 10:50 pm Post subject: |
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Modified mounting holes to fix early, late T3 and 914 cases.
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Fri Sep 05, 2014 2:52 pm Post subject: Re: BOSCH D-Jetronic Megasquirt Adapter |
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| Bobnotch wrote: |
| shconer wrote: |
| I have built a prototype board that adapts the factory Bosch D-Jetronic card edge connector in my 1969 Squareback to the DB-37 connector of my Megasquirt 2. Also I retrofitted the factory pressure sensor with a modern sensor inside. With some small modifications to the Megasquirt board to accommodate the external MAP sensor. I have created a plug and play system that works with the factory harness and does not require any further modifications or additions. Alternately you could instead connect the standard Megasquirt onboard MAP sensor with a hose to the manifold and lose the factory appearance. I have done some testing with the prototype board and I am in the final stages of developing the final version. Before I ordered PCBs and components I thought I would see if there is any interest out there for something like this. The final PCB is designed to mount inside of the factory case with room for the Megasquirt. An assembled adapter would cost approximately $80 CAD. This could be a cheaper solution for someone with a malfunctioning D-Jet ECU or a dual carb conversion. Please note that fuel acceleration enrichment is based on the MAP sensor only as the factory system does not have a TPS sensor. The factory idle control system still controls idle. This is a fuel only set up and the factory distributor and ignition is used. Also there is no provision for EGO feedback, it is a open loop system. This adapter works with MS1 or MS2 V3.0/3.52. |
That's a nice solution. Just so you know, a better version to have set up might have been the 70-71 version, as those DO use a TPS sensor.
Plus the 70-71 version seems to have the most issues, mainly due the the MPS (different from the 69 version). Just a thought. |
Actually....you could in the same spirit as the MPS mod....put a TPS inside of the stock TVS sensor enclosure....which came mid 70 to 73 on type thpe 4 engines....but you cannot use the stock type 3/4 D-jet TVS sensor guts as a TPS.
The D-jet TVS is not a throttle position sensor except at WOT and throttle closed. ...or parked with shut off.
It is not a resistance based device. It is also no rheostatic. It is simply pairs of contacts that cause out of phase injection triggers. Just positive and negative. There is no throttle position infornation supplied by the TVS. Ray |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Fri Sep 05, 2014 3:59 pm Post subject: |
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| Would this work with the later Beetle's L-Jet? |
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shconer
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Joined: August 27, 2014
Posts: 6
Location: Canada
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| Posted: Fri Sep 05, 2014 7:58 pm Post subject: |
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| raygreenwood wrote: |
Actually....you could in the same spirit as the MPS mod....put a TPS inside of the stock TVS sensor enclosure....which came mid 70 to 73 on type thpe 4 engines....but you cannot use the stock type 3/4 D-jet TVS sensor guts as a TPS.
The D-jet TVS is not a throttle position sensor except at WOT and throttle closed. ...or parked with shut off.
It is not a resistance based device. It is also no rheostatic. It is simply pairs of contacts that cause out of phase injection triggers. Just positive and negative. There is no throttle position infornation supplied by the TVS. Ray |
I see what your saying about the TVS. It would be really slick to replace the board in the TVS like your suggesting and turn it into a quadrature encoder with an analogue output.
This adapter is not compatible with L-Jet.
Last edited by shconer on Fri Sep 05, 2014 10:43 pm; edited 1 time in total |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Fri Sep 05, 2014 10:30 pm Post subject: |
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misquote - I didn't say that! ^
But an adapter like this might be good for L-Jet Bugs |
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shconer
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Joined: August 27, 2014
Posts: 6
Location: Canada
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| Posted: Fri Sep 05, 2014 11:52 pm Post subject: |
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Sorry, I fixed the miss quote.
An adapeter like this would be difficult to do for L-Jet because it has a conventional connector that is no longer made. You would have to do a minum order and they are not inexpensive. |
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Clatter
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Joined: September 24, 2003
Posts: 7551
Location: Santa Cruz
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| Posted: Sat Sep 06, 2014 8:26 am Post subject: |
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I held back, because it is OT, but I have an L-Jet bus that needs one of these badly.
After going to a longer cam to get my head temps down, the L-Jet is approaching the limits of it's tune-ability.
Also have a stroker crank just sitting here collecting dust...
That, and needing to pass a visual inspection for smog, it seems that something along these lines would be perfect.
You would be surprised at how much some of us fools would pay for things we really need (OK, Want...  )
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What’s That Noise?!? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Sat Sep 06, 2014 9:47 am Post subject: |
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| Clatter wrote: |
I held back, because it is OT, but I have an L-Jet bus that needs one of these badly.
After going to a longer cam to get my head temps down, the L-Jet is approaching the limits of it's tune-ability.
Also have a stroker crank just sitting here collecting dust...
That, and needing to pass a visual inspection for smog, it seems that something along these lines would be perfect.
You would be surprised at how much some of us fools would pay for things we really need (OK, Want... )
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Yeah...its interesting. L-jet is the later...supposedly more advanced injection than D-jet....(it is really).....but the odd thing was that L-jet is incredibly less tunable than D-jet. But what tuning there is on L-jet is easier. Just not much there.
Late D-jet MPS is very tunable. Temp sensors tunable. Valve timing, not tunable. Crank stroke is tunable as long as it does not overly disturb vacuum signature...or require so much more lift and duration in a cam that the lobe center and intake valve timing change significantly.
The only useful feature of L-jet in my opinion was the fact that allowed more freedom of cam choice. Outside of that it had poor throttle response compared to D-jet.
Both systems are limited primarily by manifold in how much larger the engine can be made.
MS is very cool.....but its weakest point for long term use is its connector system...still.
Nice thing is that its so inexpensive that most owners will probably not be trying to make it last 40 years so its not likely to run into some of the problems of D and L jet.... most using MS are using much more modern wiring materials than D and L used.....
....and even though far too many early MS connector components (primarily on the board end) are using connectors that have no place in automotive, many owners are using automotive grade component end connectors......this coupled with the tunability of MS should allow working around a lot of the "noise" created by the odd connectors. Ray |
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Sqrbckguy38
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Joined: December 21, 2004
Posts: 415
Location: Tooele, ut
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| Posted: Sat Jun 06, 2020 2:06 pm Post subject: Re: BOSCH D-Jetronic Megasquirt Adapter |
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I seem to love digging up old threads, but there's no pictures in the OP, so for anyone have recent ones or tried this? I'm still working on this for a type 3 engine, I just have so many projects in the fire I can't seem to keep up.
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69 Square needs love, even after 15 years
70 Fasty former dd, now my daughter's
67 Beetle, Opal |
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shconer
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Joined: August 27, 2014
Posts: 6
Location: Canada
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| Posted: Sun Jun 07, 2020 1:12 am Post subject: Re: BOSCH D-Jetronic Megasquirt Adapter |
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Here are the original photos and a video of it running.
https://photos.app.goo.gl/1XX5yfkaRAZV4ask9
https://youtu.be/s8xnPomrjnU
I still have my Square but sadly I have not had any time to work on it and it has been in storage. I still have the board installed and should still work but I will probably eventually just wire in a MicroSquirt and build a new harness. But if you are trying to look completely stock the best thing to do now would probably be to engineer a plug and play board that integrates the MicroSquirt Module. https://www.diyautotune.com/product/microsquirt-module-v2-2/. It does everything the MS-2 does in a much more compact and cost-effective package.
If you are attempting to go this route there are a couple of this to know. First, the factory ECU switches power to the all the injectors at the same time and the injectors are always grounded. This is very unusual and all modern ECU's switch the ground side and the injector is always powered. BOSCH most likely did this to avoid having to deal with the large voltage spikes that are created by the fuel injector coils when switching the ground side. As such the injector transistors in the MegaSquirt can not be used to directly switch the injectors using the factory wiring. I tested two different options, you can keep the factory wiring and have the Megasquirt switch a p-channel MOSFET on the adapter board that in turn switches all the injectors. This approach works but it does introduce additional dwell into the injector timing and can make tuning more difficult. Alternatively, you can disconnect the ground side blade connectors from the heads and run a switched and fused power wire to them, with this configuration you could use the Megasquirt fuel injector transistors as they were intended. I hope this helps.
Also, the lack of a conventional throttle position sensor, manifold pressure sensor and the factory trigger system in the distributor are major limitations in my opinion. In my mind going this route only makes sense if you have a completely stock running engine and maybe you have an original or restored car that has a failed ECU that can't be replaced or repaired but you want to keep the stock fuel injection appearance. Otherwise, I would upgrade to a more modern and sophisticated fuel injection system and gain all the benefits that come with it or run carbs. |
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