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Wow who would have ever though doing a swap would be this hard. I'm trying to help my friend with his 4age swap in his 1992 corolla(just like mine) and we got the engine in and everything but the wiring is such a bitch. I though if you had the engine harness and the ecu that everything would just plug up but it doesn't. Right where the ecu goes theres like 3 plugs that don't plug in together. And one of them goes to the ecu. And those plugs run behind the dash and stuff. Has anyone ever done this swap that has experience on what you have to do? Please help if you can. thanks
 

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The Mad Scientist
Lexus GS300
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There's a lot more to it than that. Here's a copy of a post I made on celicatech.net:


Engine Swap Wiring Secrets REVEALED! Written by Dr Tweak

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Keep in mind that this is not a step by step guide to wiring a 3SGTE swap, but is a general guide to wiring ANY Toyota swap. Also, yes, I am willing to help people out over email with wiring problems, but I'm not going to tell you step by step how to do it. You need to figure that out. If you would like to leave the wiring headaches to someone else, then you can send the wiring harnesses to me and I will do it for you, save for a couple wires that usually need to be wired directly to the car. The rates are usually pretty cheap too, depending on what you want done.

Basically, there are three methods of engine swap wiring:

1. Modify the COMPLETE donor car (new engine) wiring harness to fit your car

2. Modify the COMPLETE stock car (old engine) wiring harness to fit the new engine

3. Take half of one harness and half of the other and put them together (most common option)

Now, before we get too far, let me explain a few terms. First of all, the "engine harness" is the thick bundle of wires that goes from your fuse box and engine in though your firewall and to the ECU and other plugs in the car. The "engine harness" includes MANY wires that have NOTHING to do with the engine. The "engine harness" is in fact, two parts. Many people refer to the part that has to do with the engine as the "engine harness", and the other part (which is a lot of car related stuff) as the "body harness". Technically, this term is not correct as the "body harness" is the harness that goes all around your car and does all the switches and rear lights and so on. Keep that in mind.

Also when I use the term "donor harness" I mean the one going to the new engine that you're putting in. When I say "stock harness" I mean the one going to your old engine.

The term "dash harness" refers the the harness behind the dash. The "engine harness" plugs into the "dash harness" in several places, with most swaps.

I will briefly touch on the first two options. The first method can be used in cases where the two harness are very similar. For example, if you are swapping a a 2ZZGE into a car that had a 1ZZFE, you could do it. The tricky part is, you need the COMPLETE wiring diagrams from BOTH cars. Since most JDM engines we swap only have the engine wiring diagrams available, this option isn't feasible. It is an option if the donor engine is USDM and you can get the original car diagrams. Basically, you will using the entire donor harness and running the wires for the car related stuff to the original plugs for you car.

By the way, if you ever need any diagrams from any USDM car, just email me and I can get them for you for around $20.

Now, second option. This option can be used when the new engine and the old engine are quite similar in how they are controlled. For example, you can use a stock 3EE engine harness to run a 4EFTE. However, several changes will need to be made to the 3EE harness. Basically, you will take the stock engine harness and make it into a harness for the new engine. You will need to swap over some plugs, add a couple wires, and change some wiring around.

Then we have the third option. This is the most simple, most common, and in my opinion the cleanest way to swap. It is sometimes more work than the above options but gives less trouble in my opinion. So here is how you do it:

First, remove the stock engine. Then sit the two engines (new and old) next to each other. I like to do my harnesses still attached to the engines. Most of the time you don't have to totally disconnect them. Now, remember how I said the engine harness is really two different parts? Here's how it goes:

The first part is the *engine related* wiring. This is everything between the ECU and the engine itself. This is the easiest part. You DO NOT, at any time, cut, alter, or in any way molest this wiring on the donor engine!

The second part is the *body related* wiring. This is everything between the dash harness (where it plugs into the engine harness) and the fuse box, and some things on the engine. This part is a little tricky. Sometimes, if the engine has come from the same model car as yours, the body related wiring is almost exactly the same. Other times it is incredibly different! This is where you can decide if you want to use option 1 or 2 (if the harness is very similar). Keep in mind, NOTHING in this part of the harness is on the engine wiring diagrams! So that 20v silvertop diagram that you got is NOT going to help you here at all. On the other hand, if it came from a USDM car, you can get the complete diagrams and figure out what the wires do. Then you just need to swap the plugs at the fuse box and the dash harness. That's option 1.

Now, with lots of engines, and the 3SGTE is one, there is a third plug on the ECU that goes directly from the ECU into the dash harness. Normally these plugs are very similar between the old and new engines. However, on some swaps the old (or new) engine doesn't have this plug! This is where you need the engine wiring diagrams. Figure out what each of the wires goes to, and there should be a corresponding wire on the other harness.

Okay let's move on. So you already know about the third plug, that's easy, there are usually one or two other ECU plugs, and you know not to touch any of those wires on the donor engine harness. However, on the stock engine harness, the wiring is not needed and can be cut right out if you need to.

Here's what you're going to do. Starting at the ECU/dash plugs end, strip off the looming. Be careful not to cut any wires as you do so. You will notice that with many engines there is a kind of 4-way intersection of wiring right on top of the tranny. One part goes up into the engine, one goes to the firewall (ECU and other plugs) one goes to the fusebox, and the other might go off to AFM and that kind of thing or maybe the tranny. Now listen, the wiring that goes up into the engine towards the injectors and whatnot does NOT need to be unloomed on either engine, MOST of the time.

So, unloom all of the wiring from the ECU plugs and dash harness plugs right down to the 4-way or 3-way intersection, and keep going towards the fuse box plugs.

Now, I like to do this a little at a time on each engine harness, working back and forth, but you can do it with one at a time if you wish. With the stock harness from your OLD engine, you carefully trace all the wiring from you dash plugs, that is your *body related* wiring, down into the fusebox and whereever else it might go (sometimes the windshield wiper wires are in there, etc). Remove this part of the wiring from the harness.

Now pay attention: the body related wiring and the engine related wiring DO interface in several places. The biggest ones to keep in mind are the starter circut and the charging system. This is when it's handy to have the stating and charging system diagrams on hand. Normally, these systems are very similar, and you can usually use either one. Just take note of where the wiring interfaces and cut those wires, always labelling what they went to. This is why I like to do both harnesses side by side, so that I can compare them.

Keep in mind this whole time, the body related wiring that you are pulling from your stock engine harness is going BACK into your car. So take care of it. You should end up with a bunch of wires going from your fuse box to your dash harness, and a few wires cut that went to the engine. (Some of these wires will be a/c related items, oil pressure and water temp for your guages, and so on.)

Now move over to the donor engine harness. Remeber all the body related wiring that you pulled from the other harness? You're going to do the same thing here, the difference being that you want to keep the *engine related* wiring intact, so be careful with it. The body related stuff can be cut as you need to and remove it from the harness.

Then, take your body related wiring from the stock engine harness and place it next to the engine related wiring from the donor engine harness. See what's going on here? You're taking half of one harness and half of the other and making one NEW harness! Just remember, you want ALL the engine related wiring from the NEW engine, and ALL the body related wiring from the OLD engine harness.

Now you need to integrate the two. If you did a good job when taking them apart and labelled any wires you cut, you will basically be able to match them up! However, all harnesses have some differences. Sometimes, you will just leave some wires hanging that you didn't need. So don't panic if you get done and there's no home for some wiring, some of it is not needed. Also remember your wiring diagrams. They will be essential during this entire process.

Once the connections have been made, you will be all set. It should basically be plug and play. Now I will go over a couple of technical items.

Items that you need: Knife, multi-meter, wire cutters, soldering iron, solder, flux paste, wire strippers, shrinkwrap insulation, electrical tape, masking tape to write labels with, etc.

Always label a wire before you cut it.

Never loom your harness back up UNTIL the engine has been installed and it running great. That means test it for a few days first. It's a MAJOR pain to unloom a harness that you just loomed up because you forgot to hook up a wire!

Soldering: once you have the two wires you want to solder, cut a peice of shrinkwrap insulation and slide it up the wire. Then bare the two wires. You don't need a lot, just enough so that you can twist the wires around each other. Do so. Then use an acid brush or whatever and brush some flux paste onto the bare wire. Next, have your soldering iron (hot) in one hand, and the solder in the other. Hit the wire with the iron and it will sizzle and heat it up, then touch the solder to it. The solder will melt, and then it will get sucked right into the wiring. The flux paste makes it happen, it's really cool. Let the join cool naturally. Then slide the heatshrink insulation over the bare wire, and heat it up with the handy soldering iron. It will shrink over the bare wire and protect it. You're all set!

And remember, zip ties are your BEST FRIEND! Especially when putting the harness together in preperation to dropping the engine in, use them to hold the harness together and in the right places.

That's about it. Questions? Post right here.

Written by the master: Dr Tweak
 

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I'm making the same swap in my SR5...a lot more work than I thought too.
Actually after finding the plugs of the 4afe dash harness doesn't fit I found a 4age dash harness to swap it, took about and hour to change the dash harness and wasn't too hard (5 bolts to remove dash).

Everything fits except one plug wich I'm still not sure what's the use.

The engine should run this week-end if I can find all my missing parts.

Good luck on the swap...but remember that the Clusters are not the same also...so you might have some problems with the door and oil light if you keep your 4afe dash harness.

I have the 2 winring diagrams if you would like to try to modify the harness.
 

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Kliddybaba!
AE92 Sedan
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i would like to get a copy of those diagrams if you still have them snakoil
 

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1992 Corolla,
Listen to what Dr. Tweak is telling you. He built my harness and it was a snap. The engine swap was like any other; pull it and drop it in. When Tweak built my harness it was plug and play. I had 4 single wires under the dash to hook up the rest where snap in place on the engine and in the engine bay. It was worth it to have him do it. You will save yourself about a lot of aggravation.
 

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you all went the really hard way.... seriously

on my 4afe to 4age swap we pulled the stock 4afe ecu out, modified it to work at a higher RPM, threw it back in....

then as for the engine side.... you need to rewire the alternator to the intake side (i kept starter on intake side), and rewire the ignitor to work out of the old 4afe distributor (you need to have 4afe and 4age distributors that have matching internal gears).... my ignitor is in the cab near the ECU

that was all the rewiring i did. This can only be done with a smallport 4ag using the smallport high ohm injectors..... although the map isn't quite perfect.... it is still running MAP based rather than AFM. Mine dyno'd (with a poor motor) 109.6whp
 

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toyotaspeed90 said:
This can only be done with a smallport 4ag using the smallport high ohm injectors..... although the map isn't quite perfect.... it is still running MAP based rather than AFM. Mine dyno'd (with a poor motor) 109.6whp
Just so I understand this: You want someone else to do it your way and ultimately get the same results that you did? Why if I might ask would you want anyone to do that when they could have a pro help them out and make everything work the way it should?
It just doesnt seem to make a whole lot of sense to do it your way. Unless of course I'm missing something. If so please explain the part that was left out. Thanks
 

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1992corolla said:
Wow who would have ever though doing a swap would be this hard. I'm trying to help my friend with his 4age swap in his 1992 corolla(just like mine) and we got the engine in and everything but the wiring is such a bitch. I though if you had the engine harness and the ecu that everything would just plug up but it doesn't. Right where the ecu goes theres like 3 plugs that don't plug in together. And one of them goes to the ecu. And those plugs run behind the dash and stuff. Has anyone ever done this swap that has experience on what you have to do? Please help if you can. thanks
I know for sure that swap 5A-FE to 4A-GE is possible!!! Tuners from Vladivostok have already do this..(They installed silvertop) They work in "Turbomatics" (small tuning firm), thats why they could break many problems on this way. Engine installed on TOYOTA CARINA SELECT 1988 year with manual transmission.. The results was wonderful!!! And now i decided to do the same with my car. I drive 1992 Corolla AE-100 with 5A-FE under the hood, right side steering wheel and automatic transmission. And i can tell why i want to do this:

first of all 4A-GE is 165 hp
+sport air filter=170-172hp
+ through exhaust system =177-180hp
+then some weightreduction(now1000kg)
+suspension
+breaks
+ !!!very important!!! good hands, that can make it
and in result i want to get the car, that can make prety good acceleration(for this money) and it would't "eat" too much fuel...
 

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The TN Member
ae101 levin&trueno
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first of all 4A-GE is 165 hp
+sport air filter=170-172hp
+ through exhaust system =177-180hp
OK.
sorry to burst your bubble. 20v's don't make 165hp.
Toyota lied.
 

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diver9000 said:
Just so I understand this: You want someone else to do it your way and ultimately get the same results that you did? Why if I might ask would you want anyone to do that when they could have a pro help them out and make everything work the way it should?
It just doesnt seem to make a whole lot of sense to do it your way. Unless of course I'm missing something. If so please explain the part that was left out. Thanks
first off.... fuck off, i'm sure i'm 100X better at wiring fuel injection and custom setups than you are...... i've done it in several cars.... so, getting a "pro" to do it is retarded.... there's only a couple people i would trust working on my cars.... everyone on this forum looks up to Tweak as a 'god of wiring'.... him and I have had several email contacts... including him asking ME on wiring information.....

you need to understand why i did it the way i did......

first off, having the map based system to begin with is a better idea..... in the US no 4age (except for the VERY rare late 1992 prizm gsi.... which i personally have never seen, just known people whom have) came map based.... they came with the AFM setup.... more restrictive, less modifiable....

secondly...... the wiring is easy.... if you know how to modify the ECU, then you're not hurting anything..... everything in the stock system is still there (ie, airtemp, coolant temp, o2, map reading, and an ignitor) so the maps may not be 100% accurate to work with the ~70cc/min bump in injectors, but will still be running relativly stoich (mine runs rich... the o2 is shot)

third..... nobody had done it (that i knew of) the way we did..... and the end result is that i haven't met a stock longblock ae92 GTS or aw11 that can keep up... and my motor is stock, leaking oil, burning oil, and sludged up on the inside......


so... if you're asking why would someone want to do the swap a much easier way with more potential for modification in the future (ie, bandaid ecu's work better with MAP systems than afm) then you've already answered the question.....
 

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for some reason.... you just reminded me of all the ae86 guys that first saw my ae92 in person (except for the few that understood it)..... they were all saying that "you didn't do it right....".... "i'll bet it doesn't make good power with the 4afe maps".... etc etc.... and when the day ended, they couldn't keep up.....

and about 4 years later (now) i still drive it daily.... runs just fine..... your arguement is about as intelligent as the old "sr5 weak suspension" myth that was on this forum from GT-S owners... that when you swap in a 4age you need to beef up your suspension, as weights are different (laughs).....
 

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The TN Member
ae101 levin&trueno
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So with 109hp you never met another stock 4age that can keep up???

I find that a little hard to believe.

Good work on the rest of it though, it's an interesting setup.
I always respect the people that do, more than the people that just talk.
 

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:rolleyes: I asked a simple question. There was no need to for all that drama.:lol: I dont need to know why you did it that way and I really and truly dont care how you did it. Sounds to me like you are jealous of Tweak. Dont get mad because some ppl respect the work he has done. BTW, I'm glad you found a way to make it work for you, but honestly now that you've finished... do you feel better. I hope so.
All that was written in August, and you are just now responding to it. Hmmmm
 

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diver9000 said:
I dont need to know why you did it that way and I really and truly dont care how you did it. Sounds to me like you are jealous of Tweak. Dont get mad because some ppl respect the work he has done. BTW, I'm glad you found a way to make it work for you, but honestly now that you've finished... do you feel better. I hope so.

well, apparently you *did* care enough how i did it in the essence that you said something....

why would i be jealous of dr. tweak? he does work on people's cars to make money... he had a "shop" but moved and now works for someone else at a different shop..... i help people learn their cars in person (ie, show them how to do things... don't charge them... much).... we do things differently.... i respect what dr. tweak has done.... and i never said i don't.....

now that i'm finished, yes i do feel better.... because when ignorant posts go up with "well you can't modify a toyota ecu".... then someone whom knows better can chime in..... because i was able to (again, this was done over 4 years ago) do the work the way i was i have a better understanding of it works.... rather than just "well, this wire goes to that pin, and that wires goes to this pin..... and now it's 'stock' and works"
 

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Actually, I didnt say something to start with. I asked a question. I wasnt looking for an argument, when I wrote my questions and my comments. Your the one that said you had poor engine performance with only had 109 hp not me. I asked you, based on what you wrote, then you got all stupid and mad. At what, just a simple question? Then I responded, but only after that, not before. Just so we are clear about that and there is no confusion. If your way works for you.... again great, but my response was to what YOU put out in the forum about your engine. I see there are others that may be skeptical as well.
 

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diver9000 said:
Actually, I didnt say something to start with. I asked a question. I wasnt looking for an argument, when I wrote my questions and my comments. Your the one that said you had poor engine performance with only had 109 hp not me. I asked you, based on what you wrote, then you got all stupid and mad. At what, just a simple question? Then I responded, but only after that, not before. Just so we are clear about that and there is no confusion. If your way works for you.... again great, but my response was to what YOU put out in the forum about your engine. I see there are others that may be skeptical as well.
109whp out of a stock 100K+ mileage longblock is good..... most are LUCKY to reach 100whp..... so, again... your lack of knowledge is helping you a lot here....
 

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toyotaspeed90 said:
109whp out of a stock 100K+ mileage longblock is good..... most are LUCKY to reach 100whp..... so, again... your lack of knowledge is helping you a lot here....
very respectable numbers indeed. :thumbup: :cool:
 
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