Hi All, I've taken out my blown engine(5 speed manual trans) and replaced it with a low mileage engine out of a wreck. Here's the problem. The "new" engine is out of an Automatic tranny truck. The wrecker told me it would work...Everything electrical plugs in OK, but the new engine wouldn't idle and when I rev it up(mechanically sounds great) I can hear backfiring internally. No code other than "intermittent miss" on reader. Is there some wire harness tweeking that I need to do so that the new Automatic engine will run right in my Manual tranny truck?? I am using the wire harness that is on the New engine and it plugged in to all the original connections. The truck is a 2001 Tacoma 3.4 L v6, 5 speed,and the repacement engine is also a 2001 v6, but out of an Automatic trans donor truck. Any help is desperately needed!!! Thanks, Dutchy.

ps. sorry for rambling but I'm frustrated!!!

 

You'll get more help in this forum section.

 

Did you use the 5 speed harness or the automatic? I'm assuming the 5 speed cause you said original (original to which engine?) What is your problem exactly? That is is backfiring internally? Thanks

 

did you swap over your electronics/ wire harness from the original motor? or did you use whats on the new motor you got?

 

No I didn't swap over the wire harness. I plugged in the new engine's wire harness into the truck. I could understand an issue involving the throttle body, and so I would like to know what needs to be tweeked. Automatic wiring harness plugging into a Standard trans original truck must need some alterations, but everything plugged into their mate without any issues. Kinda stumped. Thanks, Robin

 

you need to swap over the motor harness. it's not hard, just a little time consuming.

 

even if the plugs are the same, the wires move around to differnt pins and this could very well be causing your miss. swap over you wire harness from the 5spd. If this does not solve it then start swapping over your coil packs from the old motor and check the plugs.

 

you should use your old harness/ecu and new engine. the only difference with the engine is the flywheel/torque converter.

 

Can someone tell me where I might find instructions for swapping over the old harness to the new engine? Or is it possible to move pins around instead of the whole harness??
Your help has been appreciated to this point. Thanks, Robin

 

If im understanding you correctly, you are just replacing your bad 3.4 engine with a working used one that happened to come from automatic.

In that case, dont swap the harness out (just leave it in) all you need to do is plug everything back in where it went on the old engine...aside from swapping the old flywheel and clutch in on to the new block.

right now Im dong a 3.4/3.0 swap, manual. However, the 3.4 donor engine came from an auto...I had to get a computer and wiring harness from a manual for mine, but the engine was the same. its possible the guys at the yard switched the intake out so i didnt notice a difference...but if you see your manual is different than the one on the auto, just use your old one.

Im not done, so I could have missed something and hopefully someone else can chime in, but I think your good to go with the above

 

all you gotta do to swap the harness is pull off the intake manifolds and unplug all the sensors/injectors. Its not hard to swap. To repin you're gonna spend quite some time downloading ewds trying to figure out whats different. The Auto harness is gonna have a lot more wires in it bacause of the trany. The best thing to do i think, is swap over to your 5spd harness. Did you check the plugs on the new motor before you threw it in?

 

Hey JPMountainboy, that's exactly what I'm doing. Replacing my 2001 blown 5speed 3.4l engine with a donor engine that came out of a 2001 automatic.
Vital22RE, I've replaced the plugs with new Bosch plugs.
I'll keep working away at it, but I'm also thinking that I'll need to cut the auto trans plug off the donor engine harness and use the end from the bad motor's harness to wire up the switches on the 5speed trans for reverse light, 4wd light etc. Thanks, Robin

 

remove all the auto trans wiring from donor engine and use only the old harness and ecu. you should not have to do any wiring splicing if you are just changing the engine...keep all your wiring as is.

as stated before, clutch changeover, and look into the tps from the auto to make sure its the same as manual...if not just use your old intake/tps...youll have it all off anyways in order to remove the injector connectors.

it should all be pretty simple

 

I cant believe I just read this.

 

Happy ending...
Yes I finally got the donor 3.4 engine running right!!! After switching the wiring harness from the blown 5speed 3.4 unto the donor auto 3.4 it wouldn't idle right. Matter of fact if I didn't play with the throttle it would die. After pulling my hair out, and requesting help from this great forum I found the problem. I gently blew some acetylene over the intake and viola!! by blowing over a certain area the motor ran almost perfect. I took the intake off and discovered a hairline crack in the plenum. So...I installed the plenum off of my blown motor and everything is good!! By the way, I will be disecting my blown 3.4 to see what came apart, but I had about 480km on the engine. I was quite disappointed because I take extreme care of my toys and other toyotas that I've had had 780km or more so it will be interesting to see what ocurred in this particular engine.
Thanks to all who gave me tips along the way!! Robin

 

so did the auto harness work with the 5spd ecu?