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Toyota 3.0 to 3.4 (3VZ-FE to 5VZ-FE) Engine Conversion

Related websites

http://www.offroadsolutions.com/ 3.4 swap parts and tech article

http://www.4Crawler.com body lift kit


http://www.techinfo.toyota.com factory wiring diagrams to download, for Toyotas 1990 and later.


http://car-part.com for parts scrounging

http://www.mindspring.com/~jayk3/toyota/tachmod.htm Jay Kop’s tach mod article

CORunner93's Conversion


His Disclaimer FIRST....This is just my experience...quote me on nothing, I accept no responsibility for any of this info if it's wrong. My swap was on a '93 4Runner with a '97 3.4L motor. Your truck and engine years will present different problems than mine did. From what I hear the only real difference is in the wiring, but like I said, I guarantee nothing here; you'll need to do some homework for your year truck and motor. The consensus with dropping this in to replace your 22R is not viable in terms of time, labor involved, parts/harness collecting, and inadequate tranny for this 6-banger. Also, due to the weight difference between the 22R and 3.0/3.4 the front suspension might need to be built up.



A two inch body lift, discussed later in this article.

The complete engine package is kind of hard to find. You will need the complete engine and pretty much everything attached to it; all the injectors, brackets, manifolds, belt driven accessories; the sensors and switches. Don't forget the two (2) O2 sensors, the MAF sensor if your motor has one, All the VSV's, the EVAP Box, and the engine wire harness, The ECU and the body side wire harness plugs that connect to the engine wire harness. The under dash ODB connector would be nice to grab too, if you need all that to work for emissions testing. I also got the 3.4L airbox. I didn't use it, but I did scavenge some of the large rubber tubes from it. That whole package cost $2,800 after taxes. I've heard of some guys finding the same package for as low as $1,500 on E-bay or from someone parting out a wrecked truck. Offroad Solutions (ORS) in Arvada, Colorado (they specialize in this swap) say the average engine package for them is about $3,000. They also have a website with a technical article on this swap. The article has a pretty complete list of the engine parts package you'll need. They also sell a conversion kit for about $1,700. It has pretty much all the conversion items you'll need, except the exhaust. Their kit also contains a conversion wire harness which would greatly reduce your headaches.

Engine Compartment Layout

They are different. All the components are on the opposite side- air box, battery, EVAP box, everything. They all have to be relocated. I just bought about 10' of steel stock (1" x 3/16" I think) and some 1/8" sheet metal and bent up brackets for the EVAP, Cruise control and fabricated a battery tray. All the stuff fits in there, with some creativity. For the air cleaner you can go with a K&N system or make your own. I bought a cheap aftermarket 3" air tube for a '99 Honda Civic and cut it to fit (same shape as the K&N air tube, but about 4" too long). Then I scavenged some of the rubber air tube from the 3.0 and 3.4L air boxes and connected it to the motor, then to the MAF sensor, then to the air cleaner. Plus I was able to get the T for the brake master cylinder in there with one of the scavenged rubber sections. There's a little more detail on the relocation stuff as I go.

Engine Mounts and Transmission

The engine bolts right up to the transmission. The 3.0L and 3.4L blocks are almost identical on the outside, so all the holes are in the same places. However, you need to use the 3.0L motor mounts. The pedestals are at a different angle on the 3.4L vehicle frames. You should buy new motor mounts if yours are worn out.


Use the 3.4L clutch plate, pressure plate and pilot bearing AND a 3.0L throwout bearing (the one for your vehicle and tranny). This is a good time to do a clutch job. Buying new parts is my suggestion. The guy at Offroad Solutions actually talked me out of a Centerforce clutch kit. They say the Toyota clutch is actually better than the Centerforce unless you are racing the thing, so take that for what's it's worth.

Oil Pan, Baffle, and Pickup Tube

The 3.4L Tacoma and 4Runner pan, baffle and pickup tube won't work, as the front differential is on the passenger on the newer trucks. You will need to either buy these items for a 2WD T100, or you can use your 3.0L pan, pickup tube and the 3.4L baffle, with some minor modification. You should be able to use the 3.0L baffle, but the way it gets sandwiched between the block and the pan bothered me. To modify, you will need to cut a hole in the 3.4L baffle for the strut on the 3.0L pickup tube. Next, dimple the 3.0L pickup tube to clear one of the baffle plate bolt caps. You'll see it when you get there. After that, just bolt on the pan and you’re done with that chore.

Belt Drive Accessories

You need all of the 3.4L accessories- P/S pump, A/C pump, and alternator. My alternator is kind of close to my steering column, next time I replace that belt I'm gong to try and find one that's about 1/2" shorter. The banjo bracket also needs to be shortened to clear the steering column (break out the blow torch and grinder). I actually used the A/C pump from my 3.0 engine and just swapped the pulleys. They're basically the same pump (on the outside anyway), but the upper manifold is different and I didn't want to buy custom A/C hoses to fit the newer fittings, plus the newer pump is for an R134 system and mine is an R12 system. Oddly, one of my original A/C lines is now too short to connect back up. I don't know why, but I'll need to find a 3" extension to fix that.

Radiator and Coolant Hoses

The 3.0L radiator is more than adequate. I've heard it's even bigger than the stock 3.4L radiator. You will need to find all new radiator hoses though. I started by buying a stock 3.4L upper radiator hose for the rig my motor came from. The upper and lower are the same on a 3.4L vehicle. As it turns out the upper hose I needed is about 2" longer and, the lower hose is about 2" shorter than the stock 3.4L hoses. Once I knew what I needed I went to a parts store and looked at a wall of radiator hoses untill I found a couple that worked. For the heater hoses I just bought some bulk heater hose to use. The heater hoses bends are pretty minor, so there is no kinking. You only need to replace the ones that connect directly to the motor. The others will be the stock fit for your vehicle.

Exhaust System

The exhaust system is on the passenger side on a 3.4L motor (drivers on a 3.0L), and is too small for the 3.4L motor (in my opinion). You can either take it to a shop and have it done, or do you own. There are a few options here. You can use the 3.4L stock manifold, but will need to have a custom header pipe made to re-route the exhaust to the driver’s side. Or you can use headers and a custom Y-pipe.

I did my own custom 2.5" exhaust, with Downey headers- bit of a pain too. First I bought a bunch of 2.5" pipe (3-8' sticks), a Flowmaster muffler, high flow cat and an 8" flex pipe....and a bunch of 3 bolt flanges. I had the shop bend a tail pipe just like the original tail pipe for my truck. Then I had them take the remaining 2 sticks of pipe and put 1 - 90 bend in the middle of one stick and an 80 degree bend at one end. On the 3rd stick I had them put 2 - 90 degree bends at each end of the pipe. Then I went home and fired up the blowtorch and sawsall. You have to assemble (and in this order, front to back) the flex joint, an O2 sensor bung, the Cat, another O2 sensor bung (scavenged from a scrap yard), and then the muffler. And, you have to do this in the tightest possible space. Make sure your CAT is short...like 8 or 10 inches or you won't have enough room. You have to put all this stuff between the tail pipe and T-Case and you'll need to be about 12" from the T-case to get the Y-pipe in. Once I had all this done and hung under the truck, I installed the headers. Really not too hard, put them on from underneath. The Downey headers come with an EGR mount. This will interfere with the steering column (at least it did on mine). I had to cut is off with a sawsall and weld on a cover plate over the hole. After the headers are done you can fabricate the Y-Pipe. You need to come off of both headers, along the tranny and T-case. For this I used the 3rd stick of pipe with the 2 - 90 degree bends at the ends I cut off one of the 90's leaving about a 12" tail. Using the longer piece for the drivers side, I cut the bent end to be flush with the collector on the header and the straigt end goes into the flex joint, along the tranny. For the passenger side I took the shorter 90 bend cut it flush with the header and the 12" tail parallel and straight along the tranny. Then I welded it to the header. I welded this one to the header, since the end of the header collector is about a 1/2" from the frame- no room for a flange there. With this welded you don't have that problem (and the header can still be removed easily from underneath). After that, I took the 2nd stick of pipe and cut off the 80 degree bend, leaving about a 12" tail. Then I cut and ground this piece so that it would fit to the drivers side pipe, right behind the flex joint, with the 12" tail running to the passenger side about 3" from the T-case and Drive shaft. This forms the 'Y' and connects the two headers. Last I took the remaining 90 degree bend and cut it to connect to the 2 pipe ends....the one from the passenger side header and the 80 degree bend coming from the driver’s side. Routing is (coming from the passenger header) along the tranny and T-case, then through the gap between the T-Case, torsion bar and frame (also the fuel filter is in there). Once everything was cut to fit and hung, I welded on all the flanges, tacked all the butt connections and then sleeved them. This pipe looks almost like the Y-pipe that NWOR makes for their 3.0L header system. They have a drawing for it on their website. It took me 2 days on the floor of my garage. I should of had an exhaust shop do all that for me. It would have only costed about $300.

Hood Clearance

You will need a minimum 2" body lift, or a hood scoop. I went with a lift for several reasons:

1) It was cheaper....I bought a 2" lift kit, with all of the shifter, steering, bumper, etc. brackets and extension for about $190 (from Roger Brown, aka 4Crawler). I do recommend his kit- went right in with no problems. The hood scoop would have been over $200 with painting the hood.

2) The lift gives more clearance for the exhaust and ventilation for the engine and exhaust, Ventilation probably isn't that important, but the extra room for the exhaust was a nice benefit.

3) Gives me more room for bigger tires.
Editor’s note: Hood fitment with a scoop has been discussed. One person was set up with a supercharger. This is a minor departure on what can be done by the average shadetree person.

Fuel Lines

The flexible fuel line coming from the 3.4L engine is on the driver’s side (passenger side on 3.0L vehicle). You will need to relocate the steel line coming from the gas tank. I just bought a 5' piece of steel fuel line and replaced the section between the filter and the motor. You'll need a small tubing bender for this. You will need to extend the fuel return line to reach to the other side of the engine compartment too. Again, I just used bulk hose for this.

Brake Lines

On the passenger side frame rail, behind the wheel, there are several brake lines coming from the master cylinder (and rear anti-lock control box, if you have that) and going to the front and rear slave cylinders. You will probably have to relocate these as they passenger side header was about a 1/4" from these brake lines. I bought a stick of brake line and some unions and routed them out and around the header along the frame. Next, I made a heat shield out of aluminum sheet and bolted it to the clutch slave cylinder. You will also want to extend that heat shield around the clutch slave cylinder, which is about a 1/4" from the header. Not much else you can do there.


Just use the 3.0L starter. It's kind of close to my headers, but there is nothing to be done for that, but insulate and heat shield the starter. This is a good time to replace your brushes!

The Wiring

This is what intimidates most people- here's how it goes! Don’t sweat the electrical stuff-it’s not that bad. I have always been horrible with electrical stuff. I've burned more wires, fried more components and electrocuted myself so many times, I don’t go near the stuff. But, this time I did my homework, and it paid off. There's a couple of key things you will need:

1) Get good wiring diagrams for both your vehicle and the donor vehicle the motor came from. Not a Chilton’s guide- you need the actual Toyota wire diagrams. Go to a website called
www.techinfo.toyota.com. It's a pay site, costing around $10 a day, but you can spend all day downloading all the actual Toyota service manuals AND wire diagrams. Took me about 4 hours to download two complete service manuals on a phone line connection....that will be the best $10 you spend on this project.

2) The revelation that there are 3 types of wires on a car. Wires that carry a negative (-) charge, wires that carry a positive (+) charge and wires that carry a signal. I don't know why, but it took me forever to understand that. I knew it, but I never really thought about it. This is important because the new engine has things that your old truck doesn't; you have to be able to figure out what kind of wire that component needs.

3) This isn't necessary, but I found it helped a lot- a big sheet of paper to map out your rewiring plan.
I made a 'Re-Pin’ diagram on a 36"x48" piece of paper. There are 2 plugs from the engine wire harness, and two from the body harness AND a 3rd plug needs to be spliced into the body harness and connects to the ECU...So, you really have 3 plugs from the body harness that need to be connected. So... I drew 3 vertical lines on the the lower half of the sheet of paper, each one representing a wire plug from the engine harness. Then I drew in evenly spaced tick marks along each line and numbered them. The tick marks represent all of the pin holes on the given plug....so if there were 26 pin holes in a particular plug, then I drew 26 evenly spaced tick marks along the vertical line that represented that plug...and then repeated that for the other two plugs.

Now....prior to all of this, I had spent many, many hours going over the wire diagrams. The wire diagrams tell you what color a wire is, what plug and what component the wire goes to AND they tell you what pin number that wire is in the plug. There are also drawings of the plugs showing the pin numbers in each of the pin holes. With a good set of wire diagrams you can identify any give wire in any given plug.
Plug connectors in the manual are drawn facing outward, with the keyway on top. Follow this form to document your connector pinouts.

So....I went back to the big ol’ piece of paper and wrote a description of each wire to the left of its corresponding tick mark...I did this for the engine first.
The descriptions included the wire color, what components it came from, whether is was a ground, a power source (and if it was, whether is came from the battery directly, or from the ignition switch, or the ECU) OR if it was a signal wire (and if it was a signal wire, what kind of signal it carried and from what component). Then I grabbed both my vehicle wire diagrams and the engine wire diagrams and just started going back and forth on each diagram until I found a wire coming from the body that either supplied the charge I wanted or went to the component I wanted. When I found that wire I wrote a description of it (that also included what plug and pin number it was). You need to be a little careful here, some components have multiple wires going to them. The wire diagrams have little descriptions of what type of wire it is (like batt, b+, FC...FP) That nomenclature is used on both diagrams so you can sort out which wire goes to which pin on the component....This is when that "3 types of wires" revelation comes into play.

There are also about seven wires that you have to add to your body wire harness, about 20 that you need to extend several feet, and I think about 20 pins that have to be soldered on. Buy a new roll of solder, and a few feet of heat shrink plastic tube. I also had to re-do my battery wire harness, as it was too short to reach the relocated battery.

Anyway, that's how I solved that problem. I actually made 3 earlier attempts to 'map' out a solution that ended up being too confusing and useless. The method I described above was really easy to understand. Once I had the 'Re-Pin" diagram drawn up, it took about 4 or 5 hours to implement my plan. I put the ECU back in the stock location and rotated it 180 degrees, so didn't have to extend all of the wires going to the ECU plugs, had to make new mounting brackets for it, but it fits nice and snug and worked out pretty slick.


The 3.0L tach doesn't work? You’ll need to modify it. It is really easy. You have to take out the gauge cluster, remove the tach and solder in a 10K ohm resister to a specific location on the back of the tach (on the circuit board).

Chili Man's recommendation

Well, I will throw in some info here as well, for when this gets archived. The 10K ohm tach mod recommended for the V6 tach also works great on the I4 tach. You do have to turn the calibration pot a tad so it will read accurately.

This would seem to suggest, for you SR5 cluster swap dudes who can't find just what you need, that an I4 tach will work on the 3.0 V6 as well, or vice-versa (same year application of course).

Power Steering Hoses

You'll need to use the 3.4L power steering pump...which works fine with the 3.0 power steering box, but the hoses don't reach. For the high pressure hose, you'll need to have one custom made. I bought mine from ORS; it was actually much cheaper than having one custom made at a shop. ORS buys them in bulk, so they can sell them cheaper. For the return hose I just used some bulk hose from the parts store. You will lose the vacuum control unit for the power steering, but I haven't noticed anything being different without it.

Other Stuff

There are a few brackets and things you will need to make to move wires, hoses and fuel lines out of the way. Nothing real hard though. I think I even managed to just modify some of the original brackets to work. Make sure you swap in the 3.0L oil pressure sending unit. I didn't and I burned out my oil pressure gauge (that and forgetting to splice in one wire were my only mistakes).

So...That's how I did it all. I'm sure I left out a few things. And thanks to all those who answered all these questions for me as I went along.

~CORunner93Willcipher's Conversion I did this swap several months ago, and here’s my take on it-

You can use your 3.0 oil pan if you run the factory IFS (bolts right up) but you'll need to modify the pickup tube to fit the 3.4 motor. I had to cut off one of the mounts for the tube and trim & dimple the 3.4 splash guard slightly to properly clear the tube. I originally was planning to use the 3.0 2wd T100 pan & pickup but my application went from 85 4cyl solid axle to 88 6 cyl IFS. You will also need to replace the dipstick tube with a 2wd T100 tube and pickup in order to fit your 3.0 pan. There's a little bit of work involved in that depending on the casting year of the 3.4. You will need to drill a hole in the block if it's 99 or newer. If you plan to do an SAS you'll need the 3.0 2wd T100 pan & pickup. I would consult Mike at ORS about the particulars.

Regarding the harness, you'll need to use the 3.4 harness and harvest the plugs from the 3.0 (N2 & N3) that attach to the body wiring. You can purchase one from Offroad Solutions or make your own if you're savvy with electronics. Either way, you need the correct EWD (electrical wiring diagram) for the motor and it would help to have the EWD for your 91 truck as well. Contrary to what others may say, you only need the 3.4 engine wiring harness and ECU, and the 2 other plugs that attach the ECU to the vehicle wiring. (no need for the entire under dash wiring harness) There is quite a bit of work to make this as you need to basically cut & splice every wire going to the ECU to do this properly. You will want to solder and heat shrink every connection if you want it to last.

Regarding the gauges- the temp gauge sender is the same resistance range as the 3.0 so its a direct hook up. the 3.0 oil pressure sender will screw in to the 3.4 block but needs to be extended slightly to clear the alternator. The tach will not work without an adaptor. I can supply you with the oil pressure sending unit extender- $10.00 and the tach adaptor- $45.00. I had to build a tach adaptor as no such beast exists to my knowledge.

The bellhousing will bolt right up to the new motor as well as the 3.0 motor mounts- However, the right side motor mount may only hit 2 or 3 bolts on the block, depending on the casting and whether or not you use the 3.4 A/C bracket. I used the 3.4 A/C bracket and compressor and swapped the top of the compressor from the the 3.0L so the hoses bolt right up. Use the 3.4 flywheel, clutch, pressure plate & pilot bearing, Use the 3.0 release bearing. You will also need to cut the P/S banjo bolt down from the 3.4 to fit your 3.0 high pressure P/S line.
Other issues- use the 3.4 alternator and splice the 3 wires into the original 3.0 harness since the plugs are probably different. Re-route the fuel lines and evap lines. Cut a hole in the hood and use a scoop or go with a 2" body lift. I did a scoop because I don't like body lifts.

Exhaust is the biggest expense / amount of work- I used Downey Offroad headers for the 3.4 manual transmission and cut them to clear my frame. Then I fabbed it to run past the transfer case and merge just behind it. It's a bugger to get the sensors, cat, muffler all in a short span before the tailpipe. Cost me around $700 for the headers, cat, muffler and labor. I can supply you with the sensor mounts- $10.00 pair. Mike at ORS may have a crossover pipe that will adapt the 3.4 manifolds to the 3.0 routing (left side). This would save you a lot of time & money. Will’s side notes from other discussions: Another note for your swap- Toyota changed the 3.4 setup somewhat in the 99 model year. They ran larger injectors and ditched the cumbersome MAF used previously along with the EGR system. Also, the earlier models 95 & 96 Taco & T100 had an ECU that wasn't capable of supporting the supercharger. However, the 96 4Runner was capable of supporting the supercharger. But, in order to take advantage of all the cool upgrades they made, you would ideally find a 2000 - 2001 Tacoma or 1999 to 2000 4Runner. To my knowledge, these are the ones that ran the larger injectors, no EGR and no drive by wire throttle system. I would avoid the drive by wire system as it would represent an additional hassle to wire. This is a fairly technical wiring project, if you're not with it so far, I would call Mike at Offroad Solutions and get a price from him.

Regarding the clutch- You won't do anything with the slave, use it just the way it is setup already. There's a bracket for the hose on the rear of the right cylinder head, just bend it a little and shim it and reuse it on the 5VZ.


Dipstick Relocation Issue

When I did mine the hole was already drilled. There was a steel plug that I had to remove though. (See Willcipher’s writeup on casting differences)

I can't imagine it's that hard to do however. The hardest part will be getting the hole drilled at the right angle. But, if you match it to your 3.0L you'll get close enough. It shouldn't have to be perfect, just close. You also want to make sure you have the pan off when you do it and clean all the metal shaving up. Place a couple of magnets next to the hole you are drilling....above and below. That could catch the shavings.
The reason you have to move it is because you will need to use the 3.0L oil pan (assuming you are keeping the IFS). The 3.0L oil pan has the sump in a different location and the 3.4L dip stick, in the stock location, will hit the 3.0L pan, not go all the way in and not give you a reading. On the 3.4L the sump is towards the front of the motor and on the 3.0L pan the sump is near the middle.

The 3.4L pan won't work (assuming you are keeping the IFS) because the 3.4L pan sump interferes with the front differential.

Like I said in my previous post though....just match the location and angle of the 3.0L dip-stick location. Response from TeamShiftPoint

Use the 3.0 oil pan. Make sure you get a 5vz block with the oil stick hole in the right spot, or you'll have to drill one out (this depends on the production run of the block).

Oil Pressure Gauge Problem with Discussion

I can think of a few possibilities here, but they are just guesses at best. Your 3.4L might have had an idiot light switch and not a sender, or your 3.4L wiring called for 2 wires, instead of one, which would incorporate the ground wire in its loop, instead of using the motor as a ground.

If you ran the 3.4L sender to your 3.0L gauge though you probably did the same thing I did and burned out your gauge. Don't be too disappointed if the gauge still doesn't work when you get the new sender hooked up. Recommendation by Chili Man:

Oil pressure gauge, be sure to use WHATEVER year/model sender matches your GAUGE, not your sending unit for the idiot light. Don’t confuse the two.

OBD Configuration with Discussion

Big kudos to TeamShiftPoint (TSP) and Willcipher(Will) for sharing their experiences in this area. Also props to 914Runner for asking questions to do his own swap, which instigated this discussion! Question: Is there a way to wire things up so the diagnostics and the check engine light still work? Also, what plugs would need to be changed on the harness? Response by TSP:It’ll will work if you do the wiring correctly. I know first hand it works; we had a bad O2 sensor, and got the CEL. we just plugged up the OBD-II reader and checked out the code, fixed the problem and cleared it. You can also connect in an OBD-II plug to the wiring, so you can get diagonistic codes easily. Response by Will:The 5VZFE harness is not long enough to reach the spot where your factory ECU was mounted. You could get away with this by mounting it above the glovebox but I chose to extend the 4 sets of plugs going from engine to ECU and ECU to body so it could be mounted in the factory spot. The original body plugs will be graphed onto the harness assy and you will need to run several additional wires to the body. Your current configuration has only one O2 sensor; the new will have 2 or 1 and an Air/Fuel ratio sensor. You will need to add this as well as the 4 wires for the OBD-II port. You'll be using your check engine light also, the factory schematics are pretty darn good (tell you what color) but I would still verify your connections with a DMM before soldering and shrinking. You need to be able to trace circuits through schematics to do this. If not, you're going to be learning this process on the fly! TSP is correct. The OBD-II port can easily be used by adding on the diagnostic plug. I found that you can install an OBD-II plug right above the hood latch pull and it looks like it was installed from the factory. Also, your check engine lamp will work just fine. The 5VZFE ECU provides a ground path to illuminate the lamp just like your 3VZ ECU. Again, you need to be comfortable with crunching through the wiring diagrams as you'll be building this mess from scratch.

Regarding your question about the plugs- You will be harvesting the plugs referred to as IH1 & IH2 in the 91 4Runner EWD. They will contain the speed sensor, check engine light, 4wd indicator, back up lights, starter signal, batt & ignition power, O2 sensor, etc.. Don't even try this without the correct diagrams. If you need to purchase them, go to
www.techinfo.toyota.com and get the 91 4Runner wire diagrams and the XXXX Tacoma, 4Runner or T100 EWD. (XXXX represents the year of the donor motor). Response by TSP:The wiring is long enough for the 90-95 4runners. It’s just long enough to get the stock location. I just flipped the ECU upside down, so the plugs are on top, then everything can plug in.
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