tyes

I’ve posted somewhere here about the 3.4 swap and was told to search, which I did for 2 weeks now. I think I have everything I need can anyone confirm my list. I need any advise to what parts I need is correct or not. I have an 88 Toyo SR5 4x4 Runner Auto 3.0 V6 3VZE.

Based on research:

1. All parts from 3.0 can swap over to 3.4? ex: starter / PS pump / alternator / oil pan + tube/ oil dip stick / etc

2. Since my car is AUTO, Buy a 3.4 motor with wiring harness + ECU (AUTO) & 3.4 will fit the A340H with only a VSS (Vehicle Speed Sensor) issue. If planning to smog, I should use a T100 (AUTO) ECU.

3.Torque converter from 3.0 (A340H) will work with 3.4.
4. Smog issue: 2 O2 Sensors = Post & Pre CAT + 2 CATs
5. NO TC or Adapters needed.
6. DIY Cross over pip & Wiring Harness & Relocate Battery


Questions:

1. I’m looking at a 3.4 from a 98 Taco + ECU (AUTO), Will this ECU plug directly to my old harness?

2. For smog/REF purpose, if I used the ECU from 3.4 and it throws an error for the VSS, can I still pass smog OR REF if all other components are install correctly?

3. I can buy the complete long block with intake, exhaust manifold, OEM headers, Fuel line + injectors, will my 3.0 parts compatible with 3.4?

4. Do different year of 3.4 motor matter when swapping in to an 88 Runner?

Elvota

I'll answer the ones I know.

Starters and alternator will swap. You'll most likely need to do some work to the alternator brackets however. The oil pans will swap, but you'll need a new dipstick tube, union and dipstick. You may have to drill out the block for the dipstick depending on year you end up with.

Dipstick - Toyota 15301-62060
Dipstick Guide - Toyota 11452-62060
Union - Toyota 0405-10033

Right... one pre, one post. The pre O2 is critical to engine operation. The post evaluates the cat only, but may be critical to pass smog.

Correct. Transfer case will be mounted to the existing tranny. Tranny will bolt up directly to the 3.4 bell housing.

There are some great writeups here on YT in regards to the crossover pipe. You do have to figure out the wiring and will have to relocate the battery (although I saw a swap where they did not move the battery... so anything is possible )

No 3.4 ECM will plug directly into your 3.0 harness. You'll have to redo some wires from the 3.0 harness to your 3.4 ECM. With an auto tranny, you'll have a few more to deal with. Get the wiring diagrams for the specific model year vehicles you are dealing with. They can be downloaded from TIS.com

Get the PS pump as well. Try to get one with a uncut wiring harness.

Newer 3.4's are more advanced and can cause some wiring headaches. Others may chime in here, but a '98 should be fine. Keep in mind that 95% of the wiring is directly between the 3.4 and 3.4 ECM. You just have to figure out a few connections such as tach, AC and tranny.

tyes

Thanks you!! I feel very confident now that especially you confirm my list. BTW I got most info from your build. Anyhow, so your saying my PS will not work. How about my AC. Here in Central Cali, we can get up to 110 degree in the sun and 105 degree in the shade. I’ve research a little about it and not really sure, seems like a lot of mix info. Another question for the experience, will the VSS effect REF/SMOG, if I decided not to purchase a T100 ECU. I know it will be a light on but I’ve read it would not affect the performance of the motor. Can someone confirm please??

BTW, 3.0 is halfway out and the 3.4 is just a drive away. =)

Elvota

The belt is wrong, but you might be able to swap pulleys. Just not sure if the 3.0 pump will mount correctly to the 3.4.

The AC compressors do swap, but you have to change pulleys. I think there is an issue with the AC amplifier and some of the wiring, but I am not clear on that. Myself living in AZ am currently trying to get the AC back together. I am about 80% there.

I do know the top caps between the two compressors are interchangeable, which will allow you to use the 3.0 AC lines with your 3.4 compressor if that would be helpful.

mt_goat

Here's a good list, even if you decide not to use their kit:

http://www.offroadsolutions.com/technicalarticles.htm

Dan.3

i have done the 3.4 swap with the h in my 88 4runner with ALOT ALOT of help from thefallman. So far I am only having one issue with my trans. Its not a big deal but kinda wierd. I still have not yet to hook up my obdII reader. Its a matter of being lazy, busy with work and other stuff going on. My issue is basically I dont have first gear with the solenoid harness hooked up kinda. Even in L it starts off in 2nd and then kicks into first at 25mph. In D it starts off in second and is a real dog up until around 25mph. Then if you let of the gas and get back on it, it takes off like a bat out of hell. Doesnt really bother me since when i take it offroad I just disconnect the solenoid connector from the trans. which reminds me, It will help if you can get the solenoid wiring harness from a 340f. you can splice it but it would just be a mater of matching up the wires to the right solenoid. My 4low is kinda wierd too. not sure if its a linkage issue yet. I will probably end up resolving my issues in the winter. For now truck runs good

yotasavg

i'm very interested in the re-use of the A340H, so if i'm correct, a t-100 ECU would control the A340H without any issues at all?

mt_goat

Here is a thread on that subject:
https://www.yotatech.com/forums/f160...-a340h-128200/

ToyoPrime1

Good thread with lots of useful info. I search by using genuine, OEM, factory, original, cheap auto parts.