HELP! Did an Engine Swap From A Sequoia to a Tundra same year 2005 4.7 4x2 Brought over Harness ECU

Now I’ve been having a hard time getting my truck to fire up . I did the swap already and now I just need help troubleshooting why she won’t fire up . I have power to my dome lights head lights ect ect . I did the reset for 15 min with the negative disconnected . I’m lost here any help would be greatly appreciated.

 

Does the starter turn the engine over? Fuel pressure? Spark?

 

The harness is likely the issue. Is your Tundra AC or DC?

 

I distinctly remember this happening to another person in the past, and the issue was, a wire or two needed to be repinned in the harness that kicks back to the ECU, if I remember right. I guess I'll use the search, try to find the post.

 

Meanwhile, EWD (wiring diagrams) are linked in the megathread (Tundra, Sequoia). Start comparin'.

 

I can't find the thread. I swear it's in here, someone had to swap the position of one or two wires in the harness, using the original ECU to the truck, I think?

 

I appreciate all the help guys what’s AC or DC it’s an automatic has the shifter where the wheels is it is missing I part that mounts onto the side of the transmission it’s a 3 prong clip I have the clip attached to the wire harness missing the piece that mounts on the side of the transmission . Can anyone please tell me what this is ? I’ll post a pic of the missing piece it’s a 2005 tundra 4.7 4x2

 

RC = regular cab
AC = access cab
DC = double cab

Cab type makes a difference, based on wiring. DC is more close in nature to Sequoia. RC and AC are similar to each other, but can be radically different than DC or Sequoia. These are all things one should know going in, before buying an engine, unless you're moving all sensors and such from the old engine over, so everything should function the same, assuming you don't try to stick a VVTi engine with a non-VVTi platform or vice-versa or start mixing drivetrains (i.e. auto into manual, 2WD into 4WD etc.)

 

It has the extended cab . I’m not sure what to call that ?

 

Access cab.

If you need more terminology help, read on. That thread also touches on drivetrain/frame swap info, a bit.

 

You shouldn’t have to swap ECU’s if it’s the same motor. Put your original back in and fire it up.

 

The 4.7 was used across a wide array of vehicles; 4Runner, Land Cruiser, LX470, Tundra, Sequoia at least. And in a couple of formats. While you'd think they'd pin everything out the same, use the same sensors, etc. it's just not what we've seen around here with similar swaps. With OP driving an access cab, and pulling from a Sequoia, you're going to run into differences.

If I ever need to do this, I'm stripping both down to the blocks, swapping all sensors and hardware etc. over, making it plug-and-play. I don't think he should attempt to use the Sequoia ECU to your point, but I also wouldn't say it's plug-and-play with the path OP chose.

 

You’ve likely got quite the battle ahead. A Seqouia ECU will not work in your AC Tundra. As @shifty` pointed out, the original ECU from your truck likely won’t pin out to the Seqouia engine harness. Probably need to unharness the motor and reharness with your original trucks wiring and ECU and sensors.

 

Ok I’ll look into this Tom I have a mechanic coming out familiar with tundras . He came out to do a diagnostic and he said he believes it’s the starter. He said he thinks the starter is not hooked up or possibly the Fuel lines he mentioned to me that there’s a few components that are in hard to reach places and he showed me on my old wireing harness how where the starter plugs in there’s a ground plate and a small bolt and he said if that bolt and plate are not properly grounded underneath the intake manifold he said the truck will not start then he mentioned there’s another possibility he said something to do with the fuel and that if another line was not grounded properly the truck will not get fuel and it will not fire up . So he was trying to do a diagnostic on the truck and we ended up calling it a night cause where I’m at we can’t wrench past 8PM and it was nearing 9:00 PM so we had to stop . But I’m going to be back at it Tom Morning at 7:00 AM with the Mechanic . I’m getting a lot of Mixed Feedback Here and it’s really throwing me off BECAUSE HALF THE PEOPLE IVE SPOKEN TO SAID IF I WENT FROM SEQUOIA TO TUNDRA I WILL HAVE TO DO THE ECU AND WIRE HARNESS FROM MODEL I SWAPPED FROM . Then HALF THE PEOPLE IVE SPOKEN WITH SAY USE THE TRUCKS HARNESS AND THE TRUCKS CPU . The AUTO-Dismantler I purchased the engine from in Rancho Cordova Ca “ Toyota-Ford Auto Recycling “ said “ if I did a swap from a sequoia to a tundra I will need the sequoia harness and the sequoia ecu “ not to mention there the Darn Issue with first gen 2000-2004 non VVT AND 2004-2006 with the VVT in the engines . I originally ripped a engine out of a sequoia from a junk yard I was planning of stripping it down to the block and I was going to port the engine oil pan area inside the block with the two main ports for the oil to flow threw and make the 70 extra HP Ect Ect but then leaned what all it would take to port the cast iron engine block and how if it was a 1000 of an inch off it could be catastrophic so I called a machine shop and checked out how much they wanted to port the block , $xxxx! I was like “ OMG How Much !? “ Starting at $1,500 and going up from there then I learned there was also a few components that would have to be added for the VVTI to still function properly so then I took the engine back to recycler for my $499 back . And I just went ahead and purchased a 2005 from the Toyota ford joint for $2,800 “Yipes!” Complete. For that price it better be right ? LOL so needless to say this has been a process my friends . I’ll keep you guys posted on this build when I find out what it what. I still have not figured out what missing connector it is that mounts on the side of the tranny also , ;-) . Problems of a Young Fellow I guess . It has been one thing after another on this truck . I had to fire 3 mechanics and tow this truck 3 times because of ETA’s or People Lying about there skill level doing this swap . One guy I had it on the back side of his home where he half axxed attempted to do the swap originally only to find out it’s his first swap and he’s getting evicted at 6:00AM by the sheriffs . I was told this the night before LOL so I had to run and save my truck and have it towed the third and final time to my house where she would be safe . So imagine ur having heart surgery and in the middle of it ur family Fires 3 doctors and has u taken to three different hospitals and now ur at the place where there doing the final parts of the surgery and then there doing your rehab . That’s what this truck is going threw. Dont worry guys I already learned if numb nuts hooked up the engine improperly buy not turning the torque converter all the way in properly my mechanic 4 th one said it’s going to blow the pump immediately. So At this point ladies and gents I’m hoping I can get it to fire up God willing . And sad to say this but I almost would like to hear anything even if it’s the pump going out LOL I’m jk jk . But in all seriousness fellas I have been praying this mother Fxxker will fire up . I have like 55-6k invested in this paperweight . So it has to turn on one way or another . He mentioned something about jumping the starter Tom also we may try before we take off the intake manifold . I Truely believe Numb Nuts the second guy with the eviction , didn’t hook up everything properly , my money says he didn’t hook up a ground somewhere properly . Where going to find out Tom and also if I need to go back to tundra wire harness and tundra ECU . TTYS about what’s what . I guarantee you guys no one on this forum has ever had to tow there truck 3 times all taken apart and fire 3 different mechanics . On the same build . LOL your prob thinking it’s me but the first guy has rebuilt 4-5 engines for me head gaskets ect ect . He had the truck for 2 1/2 months and had never started on it just diagnosed it originally he said “ the lower main seal went out on the old one “ that was going to be a major rebuild . That’s the one where they said if the bearings where one thousandth of an inch off it would not function properly . So I decided to do an engine swap cause I was told to rebuild that is like a band aid and it won’t last but 6-12 months the repair . Then his property lord said the mechanic “ was not allowed to work on any vehicles on his property untill all his projects where completed (10 different vehicles ) so I said let me get this truck the F outta here . That was the first guy . Had to let him go due to his freakin land lord . Then I’m not even going to go into the third guy . LOL . What a process . Don’t worry I’m aware that if one of these knuckle heads did something wrong it could be catastrophic, welcome to a day in the life LOL . Keep you posted Tom what’s what . Thx guys !

 

Well that complicates things.

 

what’s a lower main seal?

 

Lower main seal is where the crankshaft meets the block.

With the engine out, its not that hard of a job. Just one where if you haven't BTDT, is terrifying and likely needs special tools to complete successfully. If not done successfully, you can show how much experience you have by doing it again.

 

Front and rear main seals are not that big of a deal to change with an engine out of the truck. There's got to be more to the story on the OPs original motor than main seal. The front could even be changed in the truck (pain in the ass), the rear too (ask the mamba) if you pull the transmission.

 

But let's be real, even blaksnek admitted his seal likely wasn't even leaking. I'm dubious when someone claims "RMS" on the 4.7, I know it's happened, but compared to an SBC and how many RMS you may see in that world .... hen's teeth.

 

So the lower main seal is the same as front and rear main seals?
Interesting to swap a whole motor instead of changing the seals.

 

Don't know for sure, depends on someone's terminology. My father in law calls all the parts in an engine whatever he wants. Even if it's a different parts name.

 

I swapped a 2000 AC tundra engine into a 2004 AC tundra last summer. The engine harnesses were a little bit different from each other. I made sure to use the 2004 harness along with the 2004 engine. I also made sure to swap out any of the 2000 specific sensors with the 2004 sensors. Of course i kept the 2004 AC ECU in the 2004 truck. The engine harness is designed and installed from the factory in a way that it’s VERY difficult to remove from the engine without totally removing the engine from the truck! Too bad whoever did the swap didn’t just unplug the AC engine harness from the ECU and reattach it to the donor Sequoia engine before it went back into the AC truck.

What’s crazy is, it would probably take about the same amount of time to yank the whole engine back out of the truck to swap the engine harness, as it would to try to fish the correct harness back into the engine while it’s still in the engine bay!

 

All right so I’m going to update you guys are gonna believe me but it’s been two days. I just woke up. We did the swap we what we did was we took off the Sequoia harness and we put the original tundra harness that came with the truck on the Sequoia engine, we also put the original tundra ECU back in the truck not the Sequoia ECU my mechanic told me that was all a bunch of BS. He said original harness with the original computer same motor will work. The only thing I have to do left is have to splice 1 02 sensor because the last person that removed the harness had to cut the sensor. I forget why but he did have to cut one. So I have to spice an oxygen sensor. The truck is doing something funny. It drives good. Everything‘s fine. It’s just that when I go to do the acceleration if I’m going 45 miles an hour and I step on the gas if you know anything about tundra you know that they get it . Well, when you step on the gas, the truck bogs out as in it dies it continues to run down the road, but like loses all power and you have to just stay calm and slowly accelerator a little bit and it catches back and you continue driving 35 miles an hour Down the road 45 55 down the road . just got a few more little issues I have to work out and then this thing hopefully will be good. I’m really hoping it’s just the O2 sensor not proper fuel and oxygen ratio to the engine. I don’t know what else it could be but any help I would greatly appreciate it right now. I’ve been thinking about updating the thread the whole time I was doing this project, but I promise you guys for the last two days we’ve been working on the truck, we had to remove the intake manifold to get to the starter. We checked all the wiring. There was a bad connection on the Sequoia so he fished out the Sequoia harness and fished in the tundra harness while the engine was still in the truck. I was very impressed so we were busy for two days and I just got some rest and I just woke up about to eat breakfast so I updated as soon as I could please let me know any help with that bogging the engine like accelerator vehicle doesn’t die driving down the road. It just loses all power and it stays on and to be honest, it’s kind of scary lol

 

Have you run fueling numbers on it? How bout evap system pressure vs barometric pressure? Sounds like something is telling it to go to limp mode. You may also have a pending engine code.

 

Hot damn, it almost sounds like we were right and the mechanic was wrong. Score 1 for Tundras.com and 0 for your mechanic.

If the sensor that's disco'd is an upstream sensor, understand one thing: That's the sensor the ECU/ECM uses to read your combustion mixture, to adjust fuel/air/detonation in most EFI engines.

That said, what do I suspect is happening? You're stepping on the gas, the engine is using what info it has on combustion output, and isn't adjusting trims properly, you're bogging down.

If I were you, I'd get that O2 sensor replaced with a Denso brand unit ASAP, since these 1st gens seem to be finicky on brand of sensors. That said, @KNABORES is running at least one Bosch sensor and getting by fine. I wouldn't trust any other brand.

And in a lot of vehicles, the O2 wiring is shielded, and really sensitive to cutting/re-splicing. Make sure you don't fuck around and bullshit the repair with butt splices, wire nuts, or other bullshit. Solder, paste, heatshrink, then wrap it up to protect it.

THEN go test and see if fixed. If not, I'd urge you to start looking for a leak, starting with the intake manifold. All the vacuum hoses. But that O2, if upstream, is screaming to me as the issue, when you consider the purpose of it - those things aren't some hippie/commie farce, they have a legit purpose.

 

Great to hear the motor is running again. I’m gonna say the O2 sensor is not your problem, even though it’s a problem. The O2 sensors will default rich if they can’t come up with an appropriate reading. The throttle body is what I would be most suspicious of. Edit: Or MAF or TPS or something air meter related. You command to open the throttle plate and it falls on its face.

 

Thanks Guys Yeah I’m going to look into this a little more Tom been busy busy working the last two days catchin up you fellas already know . Hey one last thing I outta mention to you fellas is Please Don’t get on me two bad for this but underneath the intake manifold ( mind you that was a small feat getting that off about an hour so yeah my mechanic gets it off and he says to me it’s missing a hose . He said it’s called the secondary it’s the hose that runs from the back of the throttle body and it connects right into the plastic directly underneath the valves . Ok so he said that hose ain’t shit and that any plastic tube will work doesn’t have to even connect to the valve covers in the intake manifold . The entire time I’m thinking this dude is full of shit! So I tell him I’m just going to run to the dealer and get the right hose . I run to my local Toyota store they have it $75 bucks so I buy it .what does the dude say it’s the wrong hose but I can use it over here and he puts it somewhere else . This dude is really starting to piss me
Off . It’s just he’s fixed 4-5 cars for my in the past and I don’t want to give up not to mention he diagnosed it pulled the emgime out one in ripped out wrong harness fished new one in trouble
Shot it for $500 . It’s HARD to find decent help for a great price that’s why I put up with his bullshit but yeah man this shits crazy . Tom I’m taking him to 2-3 pick n pulls and I’m going to tell him that I want EVERYTHING DONE TO SPEC FOR NOW ON UNLESS WE
DISCUSS OTHERWISE ECT ECT LIKE A MODIFIED RACE CAR OR 4x4 project unless that where to remain factory with all stuff or we can’t work together. He will come around I believe I just have to be polite about how I tell him no
More
Rigging shit ur gonna fuck up something serious guessing and half assing the
Project back together. I feel like all these steps why not do it right first time
Around (gaskets orings filters sensors ect ect ) buy new everytime I can . But not everyone thinks like that . So that being said you guys think 17’s Toyota rims with some Beefier off road tires will fly on the tundra I had to put spacers it’s working it’s just like I feel like these tires Handel like dogshit ! The other night I’m putting literally down the road I hit a pit hole my shit screams and felt like was about to jolt me in a different direction LOL . I’m not even kiddin . Then a couple trench’s in the road per se and the truck wheels waited to ride every crease in the road on the way home . I know it has to have something to do with the Bigass off road tires i put
On this 4x2 like a Fuckn idiot ! LOL

 

So I had to have it towed cause I kept loosing power to the engine so I’m beaching her till I figure out the culprit of the die’s issue going forward keep u guys posted soon like Tom after pick n pull and we
Wrench for an hour or two I’ll post an update thank you guys all for all the help .

 

So the truck is good we check some fuses. The transmission was low on oil though two sensor got soldered back properly and after all the connections were double check, triple checked, and the transmission was topped off with the proper amount of oil. The truck drives. Good now the only issue left is there’s an alignment issue Because I’m running some 17 inch Toyota rims with 285 wide tires and on the stock studs it was rubbing really bad the upper control arm so I put a 1.25 spacer and now the truck is driving with the wheels one cocked out a little bit of direction Everything’s good just wanted to just finalize on the truck all right thank you guys for all your help