MickyG's MX-73 to 7M-GE Swap

mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Quick update:

Got the engine in tonight! Decided to do a test fit to see how much it'd piss me off and how long it would take. Especially since I may put the old one back in. Took me about an hour and a half so not terrible but not great! This time it was on my own so yeah Ian, I guess it can be done ;)

There's a lot to do still but I'm feeling a bit more confident about it working out at this stage. We'll see how it goes over the next few days.

I picked up a new torque wrench today and it seems to be about the same as the other one so perhaps it wasn't bad after all. I don't know but I don't think the pic below is what should happen at 47 ft/lbs!

At the very least, I'll need to pull the motor again and modify some of the connectors on the loom. I took a whole bunch of photos tonight to try to identify what's what, compared to the TEWD on both cars (I've got the MKII supra, the MKIII supra and an 88 Cressida diagram - mine's an 85 so I'm sure there will be differences).

Here's what's happened in the last week:

p587133_1.jpg


p587133_2.jpg


p587133_3.jpg


p587133_4.jpg


This is before I lengthened the boom a few days ago:
p587133_5.jpg


And this is after:
p587133_6.jpg


And this is a stretched bolt from the first torque wrench:
p587133_7.jpg
 
Tire Shredder

Tire Shredder

New Member
Sep 15, 2005
569
0
0
37
Oshawa
stay with it micky, you are much closer than you think. You've come this far, finish it! imagine the feeling of accomplishment when you get this all done.

nasty bolt! something was definatley up with that torque wrench.
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Sorry, that was the starter motor mounting bolt - it had a nut on the other side. There was a trans to motor bolt that looked similar except the threads wheren't all torn up like this one. This one was the most extreme of the ones I ruined.
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Right Now:

Working on getting all my wiring 100% perfect. You wouldn't believe how many "7MGTE into MX-73" writeups there are with all the wiring and how there's nothing regarding an MA70 7M-GE writeup ANYWHERE!

I've done well to find the MX73 wiring diagrams for my exact car but there are no pinouts of the connectors themselves. If I had that, I'd feel much more confident. I've already got most of the Supra stuff since that's so much easier to find!

Nearly there!
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Thanks buddy! And thanks for the encouragement. It's unbelievable how important that is when you get to this stage where you want to give up!
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Here's what's planned for today:

  1. Get new transmission to block mounting bolts
  2. Find a place to mount the vacuum tank (for ACIS)
  3. Sort out vacuum line routing to the vacuum tank
  4. Sort out overall vacuum line routing
  5. Rewire MA-70 (7M-GE) loom for MX-73
  6. Connect up heater hoses
  7. Connect fuel lines
  8. Mount remote oil filter and route lines

It's a big list and it's certainly possible I could finish today but who knows. My target deadline is midday tomorrow.

Number 1 is proving a bit difficult. I went to Toyota yesterday and all they had a reference for was the bellhousing to transmission mounting bolts. I even brought the ruined bolt with me and the guy insisted it was the wrong bolt! I may have to dig a little deeper so I can give him a real part number.

The other issue is number 4 - I was looking at the diagram last night and realised there's a hardline I don't posess. Here's a quick pic with the following questions:
  • Pink is the part I haven't got
  • Blue is a hose I need to identify - does it go to the charcoal canister?
  • The circled bit is something not present in the diagram - There's a large fitting (brake booster?) and a small vacuum line. I don't know where the vacuum line goes.

p589716_1.jpg


Can I get around the hard line by just routing a soft one (not sure where)?
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
This just in - that VSV that's just like the one on the vacuum reservoir? Yeah, I don't have it!!!

Off to Toyota - chances of them having it? Slim to none, I'd wager...
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Wager was correct! Only available from Japan and they're about $100! I then looked around every auto parts place I could find for something generic but to no avail! Oh well, I think it's part of ACIS and I can live without it while I scavenge the spare parts places over the next few weeks.
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Yesterday

  1. Get new transmission to block mounting bolts - DONE
  2. Find a place to mount the vacuum tank (for ACIS) - SORT OF DONE
  3. Sort out vacuum line routing to the vacuum tank - SORT OF DONE
  4. Sort out overall vacuum line routing - NOT DONE
  5. Rewire MA-70 (7M-GE) loom for MX-73 - HAH NOT EVEN CLOSE
  6. Connect up heater hoses - DONE
  7. Connect fuel lines - NOPE
  8. Mount remote oil filter and route lines - NOPE

Spent about 2.5 hours trying to find a VSV and finally gave up. After more investigation, I think this is actually for the "fuel pressure up" system and unfortunately, I don't know what this does! It is also strange that there doesn't appear to be a hole drilled for it on the block, even though there's a boss for it.

The wiring is proving more difficult than I thought. All the references out there are for Cressida 7M applications, or are for later model 5M looms. Neither of which really suit what I'm doing. So I've taken the diagrams from as much as I can get and am doing it on my own, one traced wire at a time!

The good news is that I had to remove the engine again to get access to a few things and I've got it down to half an hour!
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Over the Weekend:

While I didn't accomplish everything on my list, I did get a fair bit done so I'm no longer stressing about having no clue!

Pulled the engine to double check torque on everything I'd previously tightened down with the dud torque wrench. I'm still pissed off about that one but the high torque stuff (like the head studs) was only marginally higher than my shorty 3/8" drive torque wrench (my "control" if you like). The mid range and low is a different story! These things are meant to be within 4% accuracy. My guess is they're calibrated at the highest setting they'll read, which in my case was 150 ft/lbs! Probably totally accurate there!

Moral of the story, do NOT buy cheap tools. And by cheap, I mean if the median price is $100, don't pay $50 and expect it to be just as good!

Anyway, as previously mentioned, I have the removal/installation process down pretty well now!

I got all my power connections done for the loom and have one last main power bus to terminate on the body wiring side before moving on to the rest of the in-cabin loom. I repaired a few broken connectors on my loom as well. I had a broken water thermo sensor connector, TPS connector, Oxy sensor, and missing knock sensor cable that all required attention. Luckily, I had a donor MX-83 Cressida loom to rob what I needed from. The rest I got from the 5M loom.

My biggest achievement came last night though, when I finally clued in that I could use a DMM to check all the wires in the loom! That may sound really stupid but I was thinking the majority of the wires that weren't connected to the ECU or engine components would basically be untraceable. Imagine my shock when I discovered that was not the case!

There were a few wires that I couldn't trace but that only amounted to 5 for the 5M-GE loom. And given the 7M has all its components and still has to plug into the body wiring on the cressida, I'm more than halfway there!

Next step is the 7M loom...
 
Tire Shredder

Tire Shredder

New Member
Sep 15, 2005
569
0
0
37
Oshawa
i've never done anything as major as rewiring an engine, bit I have installed an alarm and a few other things myself. I can say that tracing the wires and getting the "big picture" of what has to be done is at least 90% of the battle. once you have it all laid out on a sheet of paper that says "this wire to this wire" all that's left is some soldering, which takes nearly no time at all.

you'll find you will have a greater understadning of how your car works in general once you're done, and be confident that it's done properly.

Looking forward to how you went about doing the wiring, I wouldn't know where to start!
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
It's been pretty surprising really! I was all worked up about how difficult this was going to be but in the end, it was MUCH easier than I thought!

Tonight:

Got the 7M wiring completely traced and have only 2 wires out of the 3 plugs (and 35 wires) behind the dash that I can't trace! Compared to the 28 wires and 4 that I can't place on the 5M, I'm pretty happy. To make things even easier, the large plug (B1 I think it is) is exactly the same between the MX73 and MA70 so it's just a few pin changes between connectors, instead of soldering. The other 2 connectors aren't going to be that easy but I'm not complaining by a long shot!

Next step is to write out everything that needs changing and document the procedure for the next guy out there. Like I've said a few times already, this particular swap has not been documented as far as I know. There are plenty of late model MX-73 with late model 7M-GTE guides, as well as a few late model MX-73 with late model MX-83 7M guides but nothing for early model MX-73 with MA-70 7M-GE guides out there that I've found.

I'll be out most of tomorrow evening so no work will get done then. Wednesday is a public holiday here though so I hope to have this all sorted by then. Fingers crossed, I'll start it up then.

To do still:
  • Make wire changes
  • Find out if I can do without the fuel pressure VSV (that's the one I'm missing)
  • sort out vacuum hose routing - there's still a bit of confusion about some lacking hoses in the diagram compared to what's on the engine.
  • Find a way to route the power steering idle up and get necessary vacuum hose in order to make it happen.
  • Drop engine in!
 
mickyg

mickyg

7MGE MX-73
Sep 15, 2005
406
0
0
46
Melbourne AU
Here's what got done over the last two days:

  • Make wire changes - NOPE
  • Find out if I can do without the fuel pressure VSV (that's the one I'm missing) - Temporarily it seems but yes
  • sort out vacuum hose routing - there's still a bit of confusion about some lacking hoses in the diagram compared to what's on the engine. - Mostly sorted
  • Find a way to route the power steering idle up and get necessary vacuum hose in order to make it happen. - Done, just need to punch a small hole in my existing accordian pipe (MX-73 has this up near the TB on a hard plastic portion of the intake piping)
  • Drop engine in! - HAH

So yeah, it's not done yet. I managed to get a full write up of the wire swapping so it's conceptually done. I didn't get a chance to actually do any of it though due to some speed bumps yesterday. Mostly to do with connectors I hadn't repaired and the aforementioned vacuum routing.

Have I mentioned how much it sucks trying to solder corroded wires in the loom? Enough to make you want to scream! The solution on quite a few has been to just crimp them. Makes for an ugly, lumpy junction but by the time I get heat shrink on it, it's acceptable.

So all the wire reparing has been done and I'm ready to start repinning the B1 and M1 connections next to the ECU - all of which will be done with the engine outside the car as it's been over the last week. I have a few A/T only wires that I need to sort still (like 2 I think) that are part of the Neutral safety switch but they should be fairly trivial.

Speaking of vacuum lines - I still have questions. There's a fitting on the top of the intake plenum that is a small vacuum line. It's part of the brake booster tap as well. There's also one at the end of the hard lines under the plenum. It's on the same circuit as the water temp BVSV. Which one of these (if any) goes to the charcoal canister? I've only got these two unaccounted for so there's going to be one that's not used. I think the unused one is for the vacuum actuated climate controls in the Supra - the MX-73 doesn't have this.

I'm sure I can do a bit more searching but my brain hurts so badly right now, I thought I'd throw this out there first! Thanks in advance!
 
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