7mgte swap... NEED HELP.

Kyle Hartman

New Member
Jun 21, 2012
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Inwood, WV
Ok well first I'd like to say is... This is my first swap ever(mkiii is my first car and only car) I bought a swap, manual. Decided to keep auto so bought a ecu and harness to plug to the motor for auto cause I felt converting to manual is too much for my plate for a daily. Well the ecu does not match my 7m-ge wiring where the orriginal ecu was. I bought a 89 ecu and harness and I own a 89 so I know the difference in yellow and gray plug nonsense. Just please let me know what I need to do/get to make this work...
 

kotu100

Active Member
Nov 23, 2006
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Use a 7mgte harness and ECU and you wont have a problem. Just make sure the ECU you get for the swap plugs into your dash harness. Theres only 2 different size plugs to ECU. So if you have a grey plug ECU and it doesnt fit you need a yellow plugs.
FYI I have an 89 and needed to use a yellow plug.

Also you CAN use a auto ecu on a mt but not the other way around.
 

kotu100

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Nov 23, 2006
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I used to be like that... cheap and supra DO NOT belong in the same sentence.
Don't do whats cheaper, if it takes a bit more time whatever, but do it the way you want it done.
 

IndigoMKII

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May 9, 2011
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kotu100;1879667 said:
I used to be like that... cheap and supra DO NOT belong in the same sentence.
Don't do whats cheaper, if it takes a bit more time whatever, but do it the way you want it done.

I don't mean cheap out on it by any means. I'm a firm believer of doing it right the first time. I was merely suggesting just pull the parts off the working 7MGTE and install them on the NA in the car.

I can think of a few things off the top of my head I would change/add. Do a walbro255 or mk4 twin turbo fuel pump as the old fuel pump is probably getting tired and the new demand of a turbo'd engine will be harder on it.
You'll also need a intercooler kit and a AFPR to control the bigger fuel pump's flow.

If you're swapping in the 7mgte, I'd install new seals and gaskets along with new spark plugs and any coolant line you can see. When the engine is in the car, it's much more difficult to replace a split coolant line with everything else in the way.
 

Kyle Hartman

New Member
Jun 21, 2012
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Inwood, WV
Can't go NA-t cause it's got a thrown rod, I thought my grammar was fine but I did fail to mention it was the body plugs to the ecu. I have both a yellow and gray plug and ecu for the swap. Yellow is manual and grey is auto... Both full harness along with it. I'm trying to use grey auto. Idk... I tried to plug it but I'll try again tomorrow. It just seemed it didn't wanna match up.
 

Kyle Hartman

New Member
Jun 21, 2012
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Inwood, WV
I know FOR SURE yellow does not match. Grey seemed to not match but then again I just bought it and decided to try it quickly, I'll just arrange them differently and turn them around some to see(a few of the clips are broke from a past mechanic... A lot of things went wrong with this mechanic, why my full rebuilt ge blew in one full year) now I will try myself.
 

Dan_Gyoba

Turbo Swapper
Aug 9, 2007
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'89 is its own special case. It's grey plug, but the plugs from newer '90+ things don't fit. The yellow plug stuff from '87 and '88 does fit. So if you got a grey-plug '90-'92 ECU/harness, it won't fit, but a yellow plug one will, with a few caveats.

I have a 1989 NA. It's got a 1987 7M-GTE in it, complete with the '87 ECU and wiring harness. Everything fit, except the ABS harness, which I hacked together by (more or less) matching wire colours. The one and only thing that did not work was the headlight idle-up. The plug is in a different spot on the '87 ECU than it would have been on the '89. That's documented elsewhere here, but I circumvented the problem by running a new wire from the headlight relay to the integration relay box, cutting the ECU out of the picture. By doing so, I lose the feature that increases idle speed if the headlights are on, but I can live with that. I may fix the actual problem with the pins at the ECU when I finish my current engine build, if I remember while I've got stuff out. I should take some pictures of the chassis grey plugs plugging in to the '87 ECU yellow connectors.

Oh, and I looked into going NA-T, and decided that the swap was less hassle, and cheaper in the long run.
 

Dan_Gyoba

Turbo Swapper
Aug 9, 2007
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NA-T can handle whatever you build it for, or have the fuel for.

The limitations on the NA for how much boost it can handle are that the pistons are higher compression (9.2:1 instead of 8.4:1) -- I don't know that this is that big a deal, and since the pistons that I'm putting in my GTE are 9:1 I expect that this is a small thing. You can deal with this by installing a thicker head gasket, or buying a set of GTE pistons.

The fuel system on the NA is another restriction. The injectors are smaller, and the flapper style AFM will max out easier. This is probably where most of the limitations are. Larger injectors and some sort of tuning device can get around that.
 

Kyle Hartman

New Member
Jun 21, 2012
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Inwood, WV
I'll have to tweak with it a little. I have both ecu's and full harnesses to match em. Just seemed like something was up like it wouldn't fit. But like I mentioned... My past mechanic broke clips so I could be trying plugs in wrong place or what not
 

Kyle Hartman

New Member
Jun 21, 2012
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Inwood, WV
Well I found out why it wouldn't fit... I feel stupid... The plugs to the abs system was visible, when I pulled the ecu out I must have pushed the plugs up and I never noticed till now! So guess I have a 87 m/t 7mgte ecu and harness for sell!!!
 

Dan_Gyoba

Turbo Swapper
Aug 9, 2007
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Alberta
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Suprabeast4x4;1881277 said:
The 7mgte is a stronger block with piston squirter too.
Same block casting, and in point of trivia, the 7M-GE got the newer, stronger block casting before the 7M-GTE. The Turbo-A spec cars used 7M-GE blocks for this reason.

The turbo blocks have the oil squirters drilled/tapped. They also have the turbo feed and drains for both water and oil, and the two front and rear knock sensor bosses tapped. The NA blocks might not. I see that my turbo block has the center knock sensor location tapped, though of course there's never been anything in it, so the threads were somewhat rusty before my block got tanked.

Aside from that the differences in the shortblock are (As I recall) pistons, and oil pump. If you're doing a GE+T, then you will probably want to change the oil pump in order to feed the turbo. The pistons will put a slightly lower limit on boost with pump gas, but you're looking at some big money before you have to really worry about that.

But this is all getting off topic of the thread, since the OP is swapping anyway. :)