I am considering doing a 3.4 swap on my 94 pickup. I know that there are swap kits from Offroad Solutions that have the harness and most other parts required for the swap. I was wondering for those who have completed the swap whether you used the ORS kit or just pulled everything from a donor rig? I am looking for an engine and stuff and I want to do the swap in the most cost effective manner. I know that they have worked out most of the bugs with their kit, but it just seems pricey to me. Any advice? Thanks

 

It is not cheap and it is not easy.

There are no bugs in the harness, there have just been screw ups in the VIN's such that harnesses were not built for the rigs.

ORS sells a harness for the 5 spd trucks that is proven. There have not been a lot of autos to do this so that is up in the air. He still does not have a tach solution.

 

When this swap first came out, it sounded like a great remedy to the 3.0's headgasket and rod problems. But I'm not even considering it anymore because of the tach problems, wiring harness problems, cost, etc. Although I love the diesel, I probably won't do it either. I think the best / cheapest solution to a failing 3.0 is a rebuilt 3.0 with stock cams, ported & polished heads & manifold, with a larger AFM and glass peened rods (maybe nitrile). I've been looking into using Extrudehone on the manifold, heads and exhaust. It'll probably still be cheaper than the 3.4 and will run like the dickens and get better mileage than the 19 mpg I get now.

 

Doing the wiring harness myself was not that difficult. Certainly not hard enough to justify the cost of the ORS harness. Took me about 4 hours to sort out the wiring diagrams, and maybe 1 hour to do the actual splicing. Everything you need is available from the donor rig. The only thing I have trouble with is the tach and a/c, which apparantly ORS hasn't figured out yet either. I am trying to reverse engineer the thing now to figure out how to make an adapter.
Hayduke, you might be right. I don't know what the ultimate power possibilities are on the 3.0, but given the money I spent on the swap, I could have gone a long way in finding out. I spent about 3500 so far on putting the 3.4 in, from buying the engine, headers, exhaust, body lift kit, catalytic converter, random bits of hardware and fuel lines, wiring harness bits that didn't come with the engine, the intake system that didn't come with the engine, etc. The exhaust system I built set me back nearly 700 including headers and cat, so that total can come down a good bit if you reuse more stock components. I also wound up getting a K&N intake used for 100 bux(thanks breezey)cuz I couln't find a stock intake that wasn't damaged. The engine package cost me 2200 which was a little less complete than I had hoped for. I still needed the wiring connector for the computer to the dash harness which I wound up having to buy an entire dash harness to get for 200 after a long and futile search to get just the connector.(friggin salvage yards, grrrrr) So learn from my mistakes and save some money there....
That kind of money could have built a pretty kick butt 3.0. BTW, I wouldn't recommend Extrudehone on anything but the intake manifold where you can't reach by hand. It's kind of a shotgun approach to coaxing more airflow. The problem is since it's a pressurized hydraulic medium and pushes in all directions with roughly equal pressure, you can't control where it removes and doesn't remove material. Ok for using a fine grit to remove casting flash only, but for real improvements in flow balanced with good velocity, a hand grinder and a flow bench are the only way to go.
I think if I went that far, I'd use headers instead of messing with the stock manifold as well. It's a poorly designed system from the log style to the collector. Reground cams might help a good bit as well, but I don't know what the stock specs are.
All that said, the 3.4 has much more potential.

 

The 3.0 is worth putting more money in? Right.

Yeah it is not cheap, but now I have a 3.4 with over 200 hp and a chance to go over 300 with bolt on stuff. Dump that kind of cash into a 3.0 and you will have a bright, shiny turd.

What are the harness issues people are talking about?

 

so, what`s the deal with the tach anyway?

 

Did you make your own headers or purchase some? Also what did you do for the cross-over? Or did you just run the exhaust out the driver side? We are going to keep the stock manifolds and make a custom cross-over out of mandrels. Other than that we are all done with the swap on our '89 4Runner.

I think there is a solution for the tach problem in the other threads about this somewhere.

I used to have a 1990 ST185 with a few mods (performance techniques rebuilt CT-26 turbo [50mm], full 3" exhaust including DP, etc) It was fun but what a $$$ pit!

We are also in SC (office on Locust St.), we should get together sometime.

 

Hectorladron:
The signal from either the ignitor or from the ECU to operate the tach and signal the proper engine speed to the A/C amplifier is different on the 3.4 so the tach and A/C won't work. I have not yet found out whether it's a variable voltage signal, a switching ground, or a switching positive signal that the tach wants. I may have to go to a shop and have it hooked up to an oscilloscope to find out what's up.
Sean:
I used Edlebrock headers(don't recommend them) and re-welded the crossover to go down the drivers side. I also had to cut and reshape the header on the passenger side to clear the frame and brake lines. There were some build quality issues due to mass production that irked me about them.
So far, all the info I have found on the tach solution does not actually detail the fix, just that a fix was found. I haven't been able to contact anyone who has actually made it work to find any details. The threads only say that one guy modded his dash, and another guy made an adapter he'd be happy to sell others interested, but neither is available any longer, apparantly. If I find out, I'll be sure to post it. I'd love to hook up and compare swap stories. "I'll show you mine if you show me yours" hehe...
My ST165 is currently awaiting a rebuild, bad rod knock at 200K miles.

 

How do you thin the cross-over flows cut and rewelded? We thought about that but gave up. I didn't know the AC wouldn't work either, bummer.

I'll be out of town through next sunday for the Off-Road Expo in LA but let's try to get together sometime after that.

 

Alltrac- if you go to 4x4wire.com and find c0runner93 he will help you with the tach. he has done it before and had helped other do it. he did all his own harness. the only problem he ran into was the oil sender. forgot to put the 3.0 back in.

 

I think we went over the solution for the tach and oil sender problems on yotatech as well.
Do a search and you should be able to find it.

 

OK, thanks gentlemen. I searched the snot out of them under swap, I'll try wiring type search words now, I guess. I'll also look up that guy on 4x4wire. Thanks again.

 

See if this link helps:

https://www.yotatech.com/forums/show...light=3.4+tach

 

That seems to explain the tach pretty good, what about the AC?

 

Yo, thanks. I just got an email from a guy on 4x4wire who sent me pics of two different tachs with the resistor on it. That should solve the tach problem but not the A/C if the info I have on why it didn't work in the first place is correct. I'm working on another approach right now that I hope will take care of both problems. I'll let you know what I find. I might have to hook both a 3.4 and a 3.0 to an oscilloscope to determine the actual signals I am trying to interpolate.

 

Glad it helped. That guy is very approchable for help.