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4A-GE/7A-FE swap research for Blacktop/Silvertop (BT/ST)

14K views 156 replies 11 participants last post by  Manny323 
#1 ·
Hey all, ive been lurking around here for the past few months and finally made a profile for myself to see if i could find some more answers to what im looking for. I have just came into possession as of recent of a mint AE102 94 Toyota corolla DX with the 1.8L 7A-FE engine (NO EGR) and 4spd trans with roughly 52000 miles on the odometer (i say roughly cause i dont know exactly off the top my head and it is legit, checked on TIS aka Toyota dealer stuff and this person who owned it drove it like 1000 miles every 3 years Jesus). Being from the rustbelt area i had another one the exact same except a 95 and it was just withering away with rust at 204k (now sold). Anyway with this ”new” corolla i wanted to plan out a 4A-GE swap. This will be my first ever full engine swap and i need all the research i can get, hence why i created this account. for starters i know the ST and BT will bolt into the same mounts n whatnot i get that, plus if i can get an automatic trans from a ST or BT combined with the engine itll be great because i do not want to go through the hassle of converting it to manual. For now im just trying to make this swap go as smooth as possible so what im looking for is a BT or ST with an automatic trans to bolt up easily. Next with wiring i hear you have to combine both the 7A harness with whatever GE harness you get because as long as you have the ecu for the GE it plugs the same, but i have two problems, one i have cruise control with this 94 (which has a separate ecu but it goes through my 7a harness under the intake) and two, would i have to tear apart my 7A fusebox to have the same connections as a BT/ST? Or will i have to just like cut open both harness looms to see what goes where and tuck my cruise control stuff into the GE loom? I know theres a few other things that go through the same hole in the firewall where the ecu sits for the body so thats what im trying to ask i guess is do i have to open both looms up to swap body harnesses inside? Three for the power steering pump i know i got to fabricate some separate reservoir and figure out what fittings go where. I have read this forum for info but he did like a fitting delete due to converting to manual AE101/102 20V Blacktop swap info so not sure what they meant by that.. fourth is a/c, im planning on using the jdm compressor but ill need to find lines thatll fit on it and route up easily to the solid line on the front right high and low side lines that run into the firewall. Now fifth i need to actually find a decent engine with trans. I found these on ebay but looking at the photos both of these had their harnesses cut at different points for idk what and idk why so i keep those tabs open but im on the fence about them, plus the price seems excessive for an engine that almost everyone wants a manual in.. JDM Toyota Corolla Levin 1.6L Engine & Auto Transmission Jdm 4A GE 4AGE BLACKTOP | eBay
then i found this front clip in maylasia but idk how importing that works and i dont want to wait like 2 months for it and then have to pay import fees or somethin idk Halfcut toyota lavin ae111 4a black top auto - Car Accessories & Parts for sale in Klang, Selangor - Mudah.my
so thats another issue too— where to buy lol
the reason im planning it this much too is because well im breaking the number one rule of car modding, playing doctor with your daily.. but i think itll look awesome and rip even with an automatic, i even thought about just bolting up my 7A trans but i hear the ratios are different and itll be more wiring work so just trying to keep it as simple as possible. hope i can find some answers!
 
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#4 ·
I'm not sure, but 1987 aw11 mr2 has the 4age with sc and automatic. You would just need to swap axles to turn it to fwd.

Everything should be the same between the aw11 mr2 and the ae86. The ae86 with motor and trans is going to be harder to find.

Since you're wanting automatic, the aw11 is the one you want. Just got to spend the extra to get the donor.

With the engine importers, your risk is that it's complete, and if it's from the chassis you need. They just buy a bunch of motors and trans at one time. It's obvious they don't really know the chassis it came from.
 
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#8 ·
I’ll be straight up and say a 16 valve NA 4AGE especially hooked up to an auto isn’t going to be any faster than your car bone stock if anything you’ll feel it is weaker. You’ll be doing so much work for 15 hp and less low end. An automatic especially our a245e is going to shift you right out of the powerband every time you get near it
 
#9 ·
Well you could override it by using the 2LO/D off feature considering it locks it into gear until you shift out or reach the safe speed for it. plus im not trying to go crazy for this first build so somethin like almost a plug n play type deal is what im lookin for and to spiff up the car is all lol
 
#11 ·
The 5 speed wakes up the 7AFE quite I bit I know you want to stay auto but that’s gonna be the simplest and most incremental performance upgrade
 
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#12 ·
Hmm if i swapped it manual how would i make it so instead of pressing the brake i have to press the clutch for it to start or can i just override that and keep it so that if i press the brake itll start? Like yknow how manuals have the clutch safety switch how would i incorperate that into a manual? I know theres a few manual trans up here so finding parks n clutch cylinders shouldnt be a problem, the problem im gonna have is positioning of the clutch master cylinder i nave no idea how to bolt it up, i know theres a little like plug up in the dash for it where the pedal sits, will i just need to drill a hold there? And if so how big? from the inside out or outside in?
 
#18 · (Edited)
That's a lot of text but I'll try to answer some of these questions :)

Engines on pallets are cut to shit, not two ways around it, that'll be the most time consuming option at the end because a lot will have to be figured out to make everything work. Your best bet is either a front cut or a donor car, lots of bits in there that'll be useful to you, complete uncut A/C system, complete uncut P/S system, and of course an uncut wiring loom, super important that bit.

About the wiring you keep the whole 20v engine loom, and graft it to the chassis loom in three different locations, the junction box in the engine bay (9-10 wires to reallocate to the AE101 junction box depending on if you keep A/C or not), inside the engine loom you'll have to splice 1 or 2 AE101 connectors directly into the charging circuit of the 20v loom, for your starter and for your headlights (may vary depending on region/version), and finally there's a connector that links the engine loom to the chassis loom inside the cabin, right above the ECU, this one takes care of your circuit opening relay, power input to your coil and injectors, speed and reverse sensors and every signal to and from your gauge cluster. Depending on which 20v you pick, ST or BT this job will be more or less difficult, the ST is from the same generation of Corolla, and thus has more similarities with your car when it comes to wiring, same connectors etc... The BT will need more work, which is why it's important to have a complete uncut engine loom, and even some of the chassis loom if possible, less guessing and more spare connectors you can use. For example for my swap I used the connectors from the AE111 chassis loom to build an wiring adapter between the BT loom and the AE101 chassis loom.

Your question about the P/S idle control valve is valid, everyone tends to get rid of it for manual cars, but afaik it's quite important with an auto and you might have to keep it to make sure your car idles smoothly when your P/S pump is under load. On your car this valve is located on the P/S pump and on a 20V engine it's located on the steering rack, so you'll have to find a way to splice it into your P/S high pressure hose somewhere, your best bet is to ask an hydraulic shop to build a whole assembly for you, using whatever spare parts you have from both the AE101 and the 20 engine and making sure you figure out the length of every hose so it can be installed properly.

You can take a look at my swap thread, I tried to add as many details as possible, and if you have any questions feel free to ask either here or in PM ;)
 
#19 ·
Yooo that was very indepth for the wiring which was my main concern, i really thought i could do the splicing and stuff on my own with the two harnesses but jesus thats alot more spaghetti than i thought it would be, plus you said i need to incorperate the valve into the high side ps line or whatever to hook up to my engine. With the harness i might as well send it out with my 7a if i do it, not sure if anyone knows a guy who does custom harnesses. As for the ps ill have to find a local hydraulic shop for my concern. also thank you for letting me know what you thought bout those pallet engines! That was my main concern it wasnt fully there and that confirms my fear, i did find a donor front half in maylasia but i have no idea how to get it here to the usa, plus i was talking to someone else on here that said the 5spd brings out the 7A better than my auto so i was starting to lean to a manual swap if this 4age thing isnt gonna work out, which it kind of isnt with my logistical issues (tiny ass garage which is a shed) and all the amenities im trying to add back with power steering and a/c lol. Thank goodness i made this thread first cause im exploring options right now and just trying to see what would be best in my situation
 
#22 ·
Unlikely I’m not 100 percent sure but there is no sensor on the manual transmission that gives info to the ecu. Aside from only a speed signal which both auto and manual harnesses have
 
#23 ·
A list I found of things you need for a manual swap. Well from a 6th gen Corolla forum I doubt it’s too different from 7th gens
Here's my list:

Auto/manual conversion checklist:

Manual tranny
Flywheel and bolts
Clutch kit (and pressure plate bolts)
Driver's side mount for manual
Shifter assembly
Shifter cables
Clutch pedal assembly
Brake pedal (or grind down your stock one)
Clutch master cylinder
Clutch slave cylinder (if not included with tranny)
Clutch lines
 
#26 ·
A list I found of things you need for a manual swap. Well from a 6th gen Corolla forum I doubt it’s too different from 7th gens
Here's my list:

Auto/manual conversion checklist:

Manual tranny
Flywheel and bolts
Clutch kit (and pressure plate bolts)
Driver's side mount for manual
Shifter assembly
Shifter cables
Clutch pedal assembly
Brake pedal (or grind down your stock one)
Clutch master cylinder
Clutch slave cylinder (if not included with tranny)
Clutch lines
Alright, but the reason i thought it might need a new harness too is cause then it doesnt have to have a few connections to the trans so id have loose connections just hanging there after (example the PRNDL position sensor) and the switch the the clutch safety cancel or whatever
 
#24 ·
In my 1997 Toyota wiring diagram manual I flipped between Engine Control (7A-FE M/T) and (7A-FE A/T) and everything looks identical except the neutral start switch and clutch safety switch.

The manual and auto ECUs may be different if only to save money by not having to put the circuits in for the automatic if not needed.

You also have the shift level lock on the auto that releases when you press the brake pedal.

You might want to pick up a used Toyota repair manual on eBay and a wiring diagram manual. Sometimes you can find a deal on both together. The 94 repair manual was 2 volumes, so keep that in mind if you search eBay.
 
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#27 ·
There is no PRNDL position sensor. That is just a cable going into the auto transmission. The only wires going into the 4-speed auto are the wires for the 3 solenoids. Then there's the neutral start switch which also controls the reverse lights. And the speed sensor which may be the same on manual and auto.
 
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#29 ·
Manual safety switch isn’t really needed tbh. For some reason the past owner didn’t wire one on so I’ve just gotten in the habit of jerking my shifter before I start every time to make sure I’m in neutral. I have a stock 6 speed ecu which makes me believe that safety switch doesn’t go to the ecu
 
#30 ·
Well what that does is essentially just kill the starter by opening the circuit through the safety switch so in reality it would never go to the ecu because its part of the starting system, but i kinda figured i wouldnt need it but it would be nice to have, i just need to know how to get rid of the brake interlock with the shifter, yknow to shift out of oark gotta press the brake
 
#34 ·
Ok so after looking at the ewd, there is a park neutral safety switch that lets you start the car in park or neutral in auto and a clutch switch on the pedal which acts as a killswitch for the starter if not pressed so i do need something to bridge the wires so i can bypass the switch or add it in and see if by chance the body harness has a plug for it tucked away for it. Another thing is i will need a new engine harness from a 94 corolla to use with the manual because it has a backup switch built into the trans and like i said earlier if the back up connecter isnt in the harness just tucked away then ill need a new one, it looks like the back up connecter is under the airbox and ill have to look later due to work but ill be on the lookout for connectors on my original harness and see if i need a new one or stick with it
 
#35 ·
OK SO FINALLY i was able to tear into my corolla abit, i took a couple pictures because one there IS a selector position switch at the bottom for PRNDL which is the big connector (see photo with red circle) and i tried looking for loose connectors for the back up switch and clutch cancel switch but i couldnt find anything, i did fine this, (see pic with green circle) but looking at the ewd and component location its a diode rip because i thought it was like a cover for the clutch switch but its just a diode. I found there was a connector for optional power mirrors taped to my dash light adjustment so i was like ok maybe this is a connector for the clutch but nope. but finally looking at the ewd and such what i will need is the connector for a back up light from the manual trans, take out the PRNDL selector, cut the park wire/neutral wire, splice it together so i can start the car without the clutch and have back up lights when i select reverse considering the switch is whatever it is connected to on the trans, so by making a pigtail of the connector from the back up switch from the trans i can connect that to my cut reverse wires and boom reverse for manual without swapping harnesses AND being able to start the car without pushing and incoorperating the clutch hell yeah B ). The only questions i have though is because i have cruise control it says theres a cruise control clutch switch incorporated as well into the clutch so i dont know if just putting the wires so it stays in park all the time will make the cruise control not work thinking its in park? Can someone elaborate on this because if i do go this route then cruise control will never work and i obviously dont want that.
 
#38 ·
The red circle is the neutral safety switch and it also controls the reverse lights. It does sense the position of PRNDL, but is only used in the starter circuit and the reverse lights circuit. It has no connection to the engine/trans computer.

The clutch switch for the cruise control is opposite the clutch safety switch. While the safety switch is activated when the clutch is fully pressed, the other switch is unswitched if you just slightly press the clutch. You obviously want the cruise to disengage as soon as the clutch pedal is pressed or else the engine will rev up
 
#40 ·
Yes. The circuits for neutral start/clutch safety switch and reverse light are the same, just different switches for automatic and manual, so just a matter of splicing wires to the new switches. And you don't really need the clutch safety switch if you are careful to remember to push the clutch or put the manual shifter in N before cranking.
 
#41 ·
Thats fine but will cruise control work when its spliced together to bypass the pn sensor? And will it work without the cruise control clutch switch? (Not the clutch safety switch) unless theyre the same? I have no idea right now due to heat outside and local junkyards dont have any manuals atm, just autos
 
#42 ·
The clutch cruise control switch is a different switch. Without that switch you could splice the wires to always be connected or always be disconnected. One way cruise would never engage. The other way if you push the clutch in while cruise is engaged the engine RPMs will skyrocket I assume. Seems like that switch is a pretty important feature. The RPMs would be limited by the computer, but you still might not want to accidently have the cruise control computer opening the throttle with the clutch disengaged.
 
#43 ·
THATS my main worry, cause like you said and i have finally found out, i can splice engine wires together no problem but the kicker is gonna be the cruise control clutch switch, i really dont wanna shift a gear and it redlines and burns my clutch while i cruise or somethin lol. Im going at it again right now to see if this body harness from the driver side is multiple pieces or if im gonna have to fully tear into my interior to get at it
 
#45 ·
I am so lost lmfao. im wondering if this is just one big harness under the dash and id have to rip it out to get it n whatnot cause jfc it splits from the center out really i guess and im assuming since i dont want to tear into my dash right now not this moment due to time constraints but holy hell
 
#48 ·
Oh lord so i finally came to the conclusion if i wanna do this ill need todo a body harness swap and engine harness swap, the engine harness is no big deal but the body oh lord. In the picture where my hand is theres those wires i pointed out earlier that go up but they join with that center blue box (which also has wiring coming from it from the right side) and goes down the side (see pic with green arrow) to the junction block. Course only way to get that harness is by tearing the dash out, its only a matter of trim pieces and stuff holding it on but man itd an involved job because the harness is boLTED TO THE DAMN DASH like who wh— why. Even for example the far right air ducts are bolted to the dash in reverse, im like bruuuuuuhhhhhh. Anyway i have still yet to find a corolla like mine except as a manual as there has been a shortage of 93-97 corollas lately in the yards. As far as im concerned if i want cruise with low chance it wont work i might as well do a body harness and engine harness to play it safe, now just gotta wait for a suitable donor to show up in a yard to get it
 
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