Good day YT,

For quite some time I was convinced that I couldnt perform a 3.4L swap on a automatic 4wd 2ndgen 4Runner. However, i recently found a thread (and some signatures) claiming that is it, indeed, possible to swap the engine while leaving the original transmission in. My tranny is the A340F and it was just rebuilt 2 months ago, so even with the extra power, it should hold up nicely for some time.

Wait, some time?

Yes. See, I also plan on doing a manual swap, but since manual trannies run at around $1k, it doesnt fit the 3.4l swap budget.

So all I need is a decent procedure to fit the tranny (if its possible). I can live with some tranny codes until the manual comes, so simple wiring will be enough. Truck is daily driver.

Any ideas? Suggestions? Bashing comments? Anything is welcomed!!

 

What thread and what signatures?

:wabbit2:

 

https://www.yotatech.com/forums/f160...-a340h-128200/

Thats one thread. I contacted two users who claimed to have done it. No answer yet.

 

One of the users (which I wont id in case the user doesn't wants to be identified) responded with:

"On my 3.4 swap, I used a T100 transmission and t-case. Not sure if you guys had that truck in Puerto Rico or not, that could be the deal breaker. My 1st transmission was the stock A340H, I had to use a T100 ecu for correct shifting and the speed sensors are different on the Tacoma and 4Runner. That transmission could not handle the supercharger and started slipping very soon after the swap. I still have a very ghetto shifter setup right now and have not figured a better setup yet. Wiring was stock"

Anyone with some light?

 

I have a stock 340F with 140,000 miles on it. It has been behind a 3.4 for 5000 miles in my 4Runner without issue. Wiring isnt all that bad once you get a diagram that isnt printed incorrectly. Regarding the actual shifting, there are only about 5 wires needed. One for each solenoid, neutral start and ground. Mine seems to shift at the right points and isnt slipping. Then again, I dont hammer it. All gears are there including overdrive and the ECT mode works.
The only issue I have, and this has nothing to do with the swap, is my speed reading is exactly 10% to fast, yet my odometer reading is 7% over. Stock tires too, so I dont know what the heck that is all about.

 

So you managed to do a 3.4 swap on a 2nd gen 4Runner with the stock transmission? Does your 4wd works too?

 

I feel completly hopeless...

If you guys cant help me, who can?!?!

*cries*

 

Yes it does.

 

Could you PLEASE tell me (and the rest of YotaTech) how you managed to make it fit? Any difficulties? Modifications?

 

Make it fit?! It bolts right up. The bolt pattern is exactly the same. The only difference is wiring. This info is plastered all over this section of the forums.
You dont touch the 4wd for the swap mechanically. There are 2 or 3 wires to change depending on if you have ADD or not.

What is your issue with the swap?

 

Well, as I said, every website and tech article I read about the swap said that the automatic transmission wouldnt fit! Even ORS, a company that used to specialize in this type of swap, said that it wouldn't fit! And, honestly, all the swap i've found here are done with manual tranny, or with an auto-to-manual swap too.

I've hadn't had any issues with it.... mainly because I haven't started it yet XD. I'm still searching for a donor vehicle, but I was also searching for a manual truck from which to perform the tranny swap. But prices here are through the roof, and when I saw that someone kept the original tranny, I had to go for it!

And yes, I have ADD (the mechanical feature, not the illness), but I'm going to swap in some manual hubs too. But I dont think that affects it in any way, cause the ADD would still work normally, but 4wd would work only on locked.

Do you mind if you can share the procedure you had to go through? Or point me to a thread, because I can't find any (literally)... at least not for automatics!!

 

I am thinking Cadman's swap used the 340H as well since I do not remember reading anything about the trans being changed out. I know that he used a Marlin adapter for the transfer case.

Maybe check out his thread as well. He used an ORS harness so that wont help on the wiring but at least you know that IT CAN BE DONE!!!

Even if I am wrong, his thread is a must read if you are swapping anyway.

 

Ok wait.....I guess I am learning something here. I thought that all of our gen truck came with 340H trannys and 340F started with the Tacoma.

Forget everything I have said so far in this thread. I know nothing of what I speak!!

 

hehe no worries. As far as I know, the A340H and the A340F tranny are the "same", except that the "F" means 4WD... and I think the same goes for most Toyota Transmissions.

 

The A340H is the 4wd transmission used behind the 3.0l in the trucks and 4runners. It uses the integrated hydraulic shifted transfercase. The A340F is the 4wd transmission used with the 3.4l. The a340f uses a mechanically shifted VF2A transfercase.

I used the stock A340h in my swap initially, then switched to a A340F out of a T100. When my swap was 1st completed I used a 4runner ECU out of a 1998. I found the vehicle would shift normal under light load but would not perform torque converter lockup. Under heavy load/wide open throttle the transmission would not upshift and the engine would just bounce off the rev-limiter. On the second key cycle I had a check engine light turn on, I forget the code number but it was a speed sensor malfunction. After some research i found that the speed sensor in the A340H differed from the sensor that the 4runner ECU wanted to see. The A340H used a reed switch sensor and the A340F (4runner and Tacoma) used a magnetic pickup coil. A little more researching and I found that the T100 A340F used the reed switch speed sensor. I purchased a T100 ECU and modified my 1998 4runner harness to work, Installed the T100 ecu and had normal shifting and lockup with the vehicles stock A340H.

The T100 ECU is the key for code free and in my case proper shifting with the A340H......

I no longer run a A340H as I found the tranny to be too weak to handle the supercharger. I switch to a T100 transmission, A340F.

Thefallman and I talked about this when he lived in Denver. I think he even Drove my 4runner to feel the shifting issues.

 

Notice any mpg gains when you used the T100 ECU on the original 340 from the 3.0? Mine too bounces off the rev limiter sometimes but not always. I adjusted the cable and fixed it for about 50% of the time.

I might swap in a T100 ecu. I'm also using a donor engine and ecu from a '98. What year T100 ecu did you use?

 

Like UKrunner, I'm interested in finding out which year is your T100 ECU from. That can be very manageable until I do the manual swap... so if you could tell us ASAP, we would be very very grateful!!!

What year did your 3.4 engine came from? Did you had to match it to a specific T100 ECU, or will any T100 ecu work?

 

My T100 ECU was from a 97. The wiring plugged right into my 98 4runner auto harness. There were some wires that needed to change pin locations but it wasn't really that bad.

I did notice a fuel mileage increase from the 15s to the 17s. The vehicle didn't run any better but the engine was in the correct rpm range more often. I don't get that good of mileage due to my right foot is 2-3 sizes larger then my left.

 

Do you have any posts about those 5 modified wires (which ones, how, to where, ect.)? It should be easier to know before hand which cables to change than to start taunting until something works....

 

Yes they are in one of my threads about the solenoids.

Have you looked at any wiring diagrams yet?