So I have been starting to list everything out for the famous 2nd gen 4Runner 3.4 swap and wanted to organize all of my thoughts and others suggestions in one place.

I'm going to be swapping in a 3.4 motor after installing the essentials (water pump, head gasket, rear main seal, etc..)

I currently have an A340H 4x4 transmission and plan on on buying an ORS wiring harness which should take care of using my existing transmission.

1. Anyone that has done this swap with keeping an auto transmission, how did it turn out? Did you have to make any adjustments?
2. Besides the ORS wiring harness what other wiring will I need?
3. I have automatic hubs now. What will I need to keep them working?

From what I've read I won't be able to use my existing transfer case.

4. Am I correct in this? If so, what have you used to make it work?

As for the exhuast I am open to suggestions on what others have done to make everything fit and work correctly. I am in Nevada and will NOT have to smog it so that is a plus.

5. What type of crossover pipe should I use and where would I put the O2 sensors?

I want to know what kind of equipment and what others have done to make this an affordable and clean build. Also, any problems I might run into would be helpful.

*I have used the search bar. Some information is outdated and conflicting so I'd like to have a clean thread of current idea.

Thanks everyone. Hoping this comes out really nice and I plan on taking pictures along the way.

 

First of all, good luck. This isn't a difficult swap by any means, but there's a lot of little things that have to go right to avoid the dreaded idiot light going off.
The point of the ORS harness is to minimize the extra wiring you'll have to do. I made my own, but if I was guessing, I'd say even with the ORS harness, you'll need to make your own battery wire.
ADD, or automatic hubs, are pretty much the same year to year and the ORS harness will make sure the VSVs do their thang.
I can't think of any reason why you would have to change your transfer case unless you wanted to upgrade to a dual transfer case system.
I went with the ORS crossover pipe. You'll want to put your O2 sensors at about the same distance from the engine as in your existing system. The only difference is you will need to add a second bung for the rear O2 sensor just behind the cat.

Patrick

 

I just finished my swap earlier this spring into a '90 pickup. Replaced the 3.0 and kept my 340h trans & transfer case. After researching the wiring and trying to set aside a few days that I could keep it all straight, I finally broke down & ordered tge ORS harness. Im glad i did. Made life easy and I was running within a couple weekends after receiving the harness. Everything has worked perfectly so far. Been driving it since May. As for the transfer case, it's integral with the transmission. Can't be changed, unless you want to add a second case ffor crawling. If you're keeping the ADD, just let them know when you order your harness. I went with Aisin manual hubs and did the ADD delete on 4wire.com. A word of caution if you haven't sourced your motor yet. If you can, find a motor/ECU combo from a T100. You'll need at least the ECU in order to get it to talk to the tranny. However, if you end up with a later model motor, even with the proper ECU, you will more than likely need a different engine wiring harness and throttle body from an earlier model to work with the transmission. Let Mike know everything you know about your truck and what you're putting in it, and he'll help guide you along. I built my own crossover from scratch and it seems to be working fine, but even that took two tries. It's a very worthwhile upgrade to tthese trucks, just be patient and make everything fit as well as you can. I'm loving driving mine now.

 

im glad that everything worked out for you! I'm pumped to finally start putting everything together. The motor that I'm looking at was NOT hooked up to a T100 trans. Will this be a problem if I buy a T100 wiring harness to hook up to the ORS wiring kit? Also, I plan on keeping my automatic hubs, is that going to be a problem?

 

My engine & harness turned out to be from a 99-00 4runner 2wd. The throttle body & engine harness were incompatible for the a340h that I was keeping because it needs an ECU from a T100 to work. So I ended up buying a junk yard harness & throttle body off eBay & car-part.com. Make sure to double check with whoever you get your conversion harness from about years & models that will work for your application

 

im confused at what you mean. I thought that I would be able to use any 3.4 engine as long as I have the T100 wiring harness. Or is that not right?

 

As for the ADD, if you're keeping that, let them know that too. It will all be included in your conversion harness. Call them before you order it. Might have to leave,a message, but Mike will get back to you. He's a very knowledgeable guy for these things and won't steer you wrong. Just make sure you're understanding everything that he needs and that you need. I had to send about a dozen emails with questions & pictures that kept popping up. Once he had all the info and I got all the right parts in, the wiring went smooth. Truck fired up the first time I tried it.

 

That is pretty much right. The mechanicals of these motors pretty much didnt change, but the computer systems did.

 

ok good because it looks like the motor I'm getting was not hooked up to a T100. Im going to buy the T100 wiring harness separately and have everything hook up to an ORS wiring harness. Does all of that sound correct?

 

That's the quick version of how mine ended up working. You need a t100 ECU for an auto trans, a t100 engine harness & throttle body, although, checck with Mike at ORS first. Seems to me there was a couple years of Tacoma engine harnesses that worked also. Then you'll need to decide on air intake, O2 sensors, MAF sensor, ow much of your motor you're going to refurbish before you put it in, all kinds of fun stuff. But that's the fun part. At least the wiring will be a breeze. One other thing on the a340h, in order to use it i had to replace the neutral safety switch with one from a t100. The plug is there in the t100 harness. I bought a new one, but you probably could source tgat from a yard too.

 

If you're going wityh ORS, before you buy anything more, call or email them with all the info you have from the parts you have now. Then proceed. It will make things easier for you and them.

 

well I'm trying to locate an engine that was previously hooked up to a T100 transmission. Every place I have called so far tells me that there is no difference between the engine no matter what trans it was hooked up to.

 

Well, they're partly correct. The engine itself remained nearly unchanged for it's entire run. The difference is in the electronics for the different transmissions put behind it, and the fuel metering systems. For example, my motor and engine harness turned out to be from a 1999 or 2000 4runner 2wd. Because I wanted to use my existing a340h trans from my 1990 pickup, I had to use a t100 ECU. That meant I needed an engine harness that matched the ECU, which also meant I needed an earlier throttle body with the correct TPS. Most of the sensors and plugs were the same between the two harnesses, except for the TPS and the transmission plugs. The engine itself doesn't care, but the computer needs to find all the stuff it's looking for to be happy.

 

I just installed a 5vz in my 1992 auto 4runner 4x4 sr5 and need help with the wiring. I have a complete 1997 auto t100 4x4 sr5. I want to use the original 1992 trans. Been searching the threads for someone the made there own harness for this application. Are there any threads with this info?

 

I was in the same boat. Found a lot of info with guys who went with a standard, but not much in the way of keeping the old a340h. Guess it's not as desirable for what some of these guys want to do with their rigs. I finally got frustrated enough to break down & spend the $750 for the adapter harness from ORS. My truck's been running for almost a year now, and I couldn't be happier. The old auto seems to be just fine, just don't drive it like you stole it. I've pulled my camp trailer up into the mountains with it and taken it on a few hunting trips with no issues. If you have access to a complete t100 auto 4wd, you're way ahead of where I was. I ended up sourcing everything on the internet. Got a little spendy real quick. You'll need the ecu, complete engine harness, the throttle body with sensors, and the neutral safety switch to start off. Wiring diagrams from both rigs will be a necessity. All the evap equipment will be helpful too, or you'll have a constant CEL. If you can swing the plug & play harness, go that route. I went from starting to attempt it myself about five times over two years, to having it running within two weeks of getting the harness from Mike & his boys.