# Plug and play megasquirt harness for a vr6 distributor



## cant get a password (Sep 24, 2004)

Well this is my attempt to make a plug and play harness for my 95 VRT Cabrio that I have been working on for a while. Just got my megasquirt setup for it I bought a used setup and sent it to Paul to get me squared away and to make sure it worked.Thanks Paul for turning it around quickly Iknow how it is working a 9-5 and kids plus doing your own thing on the side.

I tore a dead 68 pin motronic ecu down to get the 68 pin connector off of the stock ecu main board and took female molex pins and soldered them onto the needed pins and bent the extra ones down.I then took shrink tubing and insulated them from being able to touch each other and the unused pins.

I then took the male ends of the molex plug end and soldered/shrink tubing to the harness and will be extending the grounds and wrapping them seperatly from the portion of the harness going to the 68 pin motronic ecu plug.

My megasquirt and harness were used which is why the harness was cut down already and why I need to extend the grounds.I will also be running a second ground harness from the gutted ecu out for all my sensors and will ground the harness grounds and my sensor grounds together.

The relay is for the fuel pump I used an existing tapped hole to attach it. I had to trim back some of the metal off the end of the ecu portion to get it to sit flat and go into the original ecu cover.

Once everything is working and pinned correctly I will take shrink tubing and shrink it over the joined male and female molex pins so they will not come undone.

Well let me know what you think I hope to try and get it installed this weekend and maybe hear it crank.










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And a link to the build.http://forums.vwvortex.com/showthread.php?3987214-My-VRT-Cabrio-build.&highlight=cabrio


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## wantacad (Apr 4, 2003)

That's so cool.


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## highbeam (Oct 3, 2003)

Nice I might be interested in gettin one done for my OBDI VR Jetta if yall are willing to share info :beer:


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## Prof315 (Jan 5, 2009)

I'm working with a couple of people on building 68 pin Motronic Megasquirt P&Ps. We're still in the prototyping stage but eventually should have MS2 and MS3 systems in a custom aluminum case that will bolt into the stock ECU location. Another planned feature with this set up will be a custom tuning cable that will plug into a factory ODB2 diagnostic port. Coverage will start out on Mk3s and hopefully expand to Mk4s (different connector).


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## need_a_VR6 (May 19, 1999)

Glad I could help! I wish the day job was only 9-5 though, I'd have SO much more time!

I have the 92 and 95 pnp pinouts in threads here if folks want to go down that same route. 

Jeff, interesting for sure. I do a few pnps but connectors are getting scarce. You have access to new ones?


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## Prof315 (Jan 5, 2009)

need_a_VR6 said:


> Glad I could help! I wish the day job was only 9-5 though, I'd have SO much more time!
> 
> I have the 92 and 95 pnp pinouts in threads here if folks want to go down that same route.
> 
> Jeff, interesting for sure. I do a few pnps but connectors are getting scarce. You have access to new ones?


No that's gonna be part of the deal.... we'll ask for the old factory ecu to steal the connector from. We've actually got a dozen or so 68 pin ecus kicking around right now.


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## cant get a password (Sep 24, 2004)

Diy autotune said they were looking into getting them made they have the 55 pin motronic plugs so it might be soon which will be real nice to see.


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## need_a_VR6 (May 19, 1999)

Cool Jeff, keep me posted on what you come up with. We might want to align a little on it.. so we're not competing directly if we can help it.


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## Prof315 (Jan 5, 2009)

cant get a password said:


> Diy autotune said they were looking into getting them made they have the 55 pin motronic plugs so it might be soon which will be real nice to see.


Yeah but 55 pin connectors don't work with 93 -99 VWs they are all 68 pin and the Mk4s are 88 pin.


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## cant get a password (Sep 24, 2004)

Okay made some progress this weekend wired up the relay to turn on the megasquirt and madea ground harness for all of the sensors coming off of the motronic harness.










I opened up an exisiting hole in the firewall to run my megasquirt harness and the vaccum/boost line for the megasquirt.










Then I hooked up the harness and made sure I was getting power and could see everything in megatune.











just going slow now and checking everything works before I try to crank it hope to have it fired today sometime.


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## cant get a password (Sep 24, 2004)

Well it is up and running had some issues with the zeitronix wb reading correctly but got that sorted out. It still needs a bit of tweaking but it is ready to hit the streets for some tuning can't wait.


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## need_a_VR6 (May 19, 1999)

The output on that one is annoying, it's 'almost' 10-20afr is 0-5v!


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## cant get a password (Sep 24, 2004)

I have not had much time for the car with 55-60 hr work week,my side job and a new baby boy so will throw this out there for you guys. The car is up and running but it bucks when you close the throttle and try to get back on the gas with light throttle input. I need to see if it is going lean when it does this or is there something else I should look at first. Like I said I might get 30 min. on a sunday to mess with it at best and didn't think to look at the afr when it bucks. From reading I also need to make sure I am tuning with speed density and not alpha-n.


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## need_a_VR6 (May 19, 1999)

Its either ve lean at low load and mid map or an accel problem. The best way to tell is to slowly decel through that same area off fuel cut and see what the afr is. If its lean add ve fuel, if its ok start cranking ae.


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## v.i.massive (Oct 16, 2006)

any updates on this


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## cant get a password (Sep 24, 2004)

I got the bucking to go away by switching the accel enrichment from tpsdot to mapdot now I need to hook up my turbo plumbing and start tuning for boost now.


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## cant get a password (Sep 24, 2004)

Okay we have boost!!!!! This thing runs so much better right off the bat than it ever did on c2 42# dizzy chip that was in it before. i just need to put some miles on the new motor and all will be good from here.


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## cstanley19 (Sep 23, 2006)

c2 doesn't make a 42# dizzy set up. They have 42# coilpack obd2


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## Prof315 (Jan 5, 2009)

cstanley19 said:


> c2 doesn't make a 42# dizzy set up. They have 42# coilpack obd2


The point here ( suprise, suprise.....NOT  ) is that megasquirt once again outperforms a chip tune.


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## ValveCoverGasket (Mar 20, 2002)

Prof315 said:


> The point here ( suprise, suprise.....NOT  ) is that megasquirt once again outperforms a chip tune.


cant beat it for flexibility :thumbup:


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## cant get a password (Sep 24, 2004)

Yes c2 "did" make a 42# dizzy obd1 chip as I and a few others bought them back in the day. it was a chip they didn't offer on their website it was a one off custom tune for a specific car and they sold it about 4 years ago to anyone who wanted to try it. I had to run an apexi afc to make it run half right it would buck like crazy under light load you had to take the old one peice maf and make your own 4" housing for it. Look in my build thread and you will see the maf you had to make to run the old style maf on the chip.

http://forums.vwvortex.com/showthread.php?3580293-my-vr6-turbo-buildup


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## cant get a password (Sep 24, 2004)

Well the car passed Texas tailpipe emissions first try so I am legally on the road. I have been taking it out at night and tuning it so glad I went with ms this time around forgot how much I enjoy cruising with the top down. It has been sitting for 2 years just lost interest after I lost the last motor in it but it sure runs good now.


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## Prof315 (Jan 5, 2009)

:thumbup:


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## Cexar_h (Mar 24, 2009)

Suscribed


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## cant get a password (Sep 24, 2004)

Sent from my LG-P769 using Tapatalk 2

Prof315 did you ever get the pnp thing going yet?


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## Prof315 (Jan 5, 2009)

cant get a password said:


> Sent from my LG-P769 using Tapatalk 2
> 
> Prof315 did you ever get the pnp thing going yet?


Sadly the guy who was doing the machine work moved before things got very far. I'm thinking about messing with it some more but using DIYAutotune's new MS3 Pro module instead.


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## need_a_VR6 (May 19, 1999)

I was thinking the same but lack of a source of new connectors keeps me from even bothering.


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## Prof315 (Jan 5, 2009)

need_a_VR6 said:


> I was thinking the same but lack of a source of new connectors keeps me from even bothering.


Yeah, I hear you Paul. I have 8 or 9 68 pin ECUs laying around but they are a pain to work with.

On a completely different subject, any luck with the bi-directional control on an OBD2 throttle?


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## need_a_VR6 (May 19, 1999)

Fried my stim with too much current and working on a better test rig at the moment.


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## Prof315 (Jan 5, 2009)

oops!


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