I finally managed to get the 4T80e swap to idle. After replacing the coolant temp sensor with a brand new unit, I discovered the temp sensor and its connector weren't making proper contact. I fixed that by taking some light gauge wire, removing it from the insulation, and stuffing it inside the two prong connector, which filled any space. Now the sensor actually reads, but the car is running a little hot, 195-215. The car is stationary, and both the fans work, but I'm not that concerned about the cooling right now. What I am concerned about, is how crappy the engine idles. Without the MAF plugged in, it will idle at about 450-550rpm, which is 300rpm lower than my daily, but I'm betting that's tune/trans swap related. When I plug the MAF in however, I can't get the engine to idle, and the MAF sensor reads 0.01 at idle and 0.05 at 3000rpm. In comparison to my daily, which reads 3.5-3.9 at idle. I know the sensor is good, because I'm using the one out of my daily, so theres probably a wiring issue or something weird causing the value to be extremely low. Theres also a misfire in the front bank, which I'm hoping is due to the MAF situation. I checked for spark on cylinder 1 because that's the one I suspected, and its got spark. I'll check 3 and 5 when I get the chance. The last thing I did today was finish bleeding the coolant system, and let the engine go through a full heat cycle, but I lost oil pressure right at the end of that. The tone of the exhaust didn't change, and the engine didn't lock up or stall. I shut it off as soon as I noticed the gauge. There also was no oil on the ground, so I'm betting I just burned through the sensor wire or something stupid.

The video below is from earlier in the day. I have since reinstalled the air box, bled the coolant, and installed vacuum lines, but the exhaust still sounds the same. Same misfire sound coming from the front bank.

 

Sounds like a big wiring basket case with that many electrical issues. Are you sure you've got all the engine grounds hooked up? Are they making good metal to metal contact (ie not installed over fresh paint or anything)?

 

I just checked them, along with the oil pressure sensor connector. The oil pressure connector had some weird, oily liquid in it, which doesn't surprise me, since the engine has gotten wet a few times since it was put back, and the passengers side axle had previously failed, getting grease everywhere. So I cleaned that, and hopefully I have oil pressure. As far as the grounds go, I have the main ground from the battery connected to the front trans mount. I did paint that mount, but I have the wire connected between the bolt head and a washer. Both of which I stripped the coating off in the areas needed. The other grounds I remember removing were two that were grouped together with the main ground from the battery, but I had to move them to the drivers side trans mount because of their length. That trans mount is not painted, and the ground wires are sandwiched between the steel mount and the bolt going into the trans case. Stock, all three of those wires were grounded with a bolt to the right of the starter on the trans case.

 

I need a new exhaust due to clearance issues with the new 4T80e, so I bought all the things I need to fabricate the custom headers I 3D modeled. I have had all the pipe for a while, but was waiting on the flanges from ZZP. I already had to make a slight revision. The runners for cylinders five and six, the ones closest to the flexplate, run directly behind the spark plug, leaving no way to plug the boot in. I already found a possible solution to this, making a slight revision in my 3D model. Instead of putting the 90 bend right on the flange, I believe putting a 2" piece of straight pipe between the flange and the 90 should give me enough clearance for the spark plug boot. I'll have to double check it in the morning, when I start tacking all the runners together. Also, in oder to get more clearance for the headers, and the trans swap in general, I replaced the stock radiator fan shroud with two aftermarket 12" fans. They give me an extra ~2.5" clearance, which is super helpful for accessing the spark plug boots. More pictures on clearances and stuff tomorrow when I have sunlight.

 

This project is taking way longer than I had hoped, but I'm still slowly chipping away at it. I have the ebay turbo, and zzp intercooler kit ordered. I originally wanted to get the larger 24x12x4" IC from zzp, but after four weeks I couldn't anyone to set that up for me on there end. There's no option to order it on their site, you have to submit an email and get it ordered that way. So I ended up settling on the 22x8x3.5" core instead. I'll upgrade it to a mishimoto core that has the same size as the larger zzp core later on. I'm still making the headers, and I have to wait on the turbo to make that mid section that'll join the two banks

In other news, I got super close to taking the 4t80e swapped car for a test drive, but that wont be happening now. To get that car to idle, I rigged the cable to get the throttle body to stay open. I still don't know why it wont idle. I have a theory I'm about 50% on. If you have a manual car in 1st gear and you dump the clutch without giving it some gas, most of the time it will stall. The theory is that's whats happening with the 4t80e swap. It's like trying to get a manual car to idle with no clutch. But the reason I'm not 100% about that theory is that it still wont idle with the transmission in neutral, where there shouldn't be that much, if any, extra load on the engine. But, back to why I can't test drive it. I don't have a shift cable yet, so I idiotically decided it would be fine to put the transmission in drive and start the engine in order to move it up and take the rear tire chocks out. The engine revved up on startup with enough force to split the trans case open. It cracked right where my transmission mount bolts to, so at least my mounts held up. But yeah, I need to get a new back half of the trans case for the 4t80e now.

 

If you think its acting like a manual, are you sure the torque converter isnt locked / trying to lock? Getting the engine to idle with a 4t80 should be no different than a 4t65 - in park / neutral, there should be no power going to the wheels and thus no real drag on the engine. In gear, the torque converter should be slipping to allow the engine to idle normally. No factory 4t80 car had to be given gas to not die like a manual.

Looks like you solid mounted the trans to the frame, does it come like that in any factory 4t80 application?

What I'm wondering is if the mount type caused the case to break as most lower mounts I've seen have some kind of rubber/poly in between to allow for flex & not transfer the stress to the case. Solid mounting is a thing in race cars, but the whole powertrain is solid mounted (often with an engine plate) so that there is no relative movement between the powertrain and chassis. If you've still got bushings in the upper mounts, that would allow the movement on part of the powertrain but not the other and the relatively thin wall trans case was the weak link.

My concern is that if it blew the case apart with whatever small amount of power it was making NA off a start rev, it's going to be way worse launching this thing with a however many hp turbo setup that will impart far more stress.

 

It didn't feel like power was being delivered in park/neutral. Power was defintely being delivered when I had the engine running and in gear. When I started it and it spit the case, that was I think the third time I had started it in gear. But that was the first time I had started it in gear with the throttle rigged to stay open about 2-4% so that it would idle. The torque converter could be locked. I haven't gotten to test the trans controller yet.

I have the engine and trans both solid mounted to the frame at three points. I know the reason it crakced was half starting it in gear at part throttle, and part not having the front mount for the trans connected. I was moving a ground wire and stripped the threads a little trying to reconnect the mount. The front mount is the one which would primarily prevent the engine/trans from rocking, and it wasn't connected during this mishap. As far as factory application, no engine/trans I know of comes solid, or even poly mounted. They're likely all solid rubber, and in some cases like the 3800 engine mount, rubber with a type of grease/fluid inside. The 4t80e I pulled from the aroura was mounted to it's subframe with rubber mounts.

 

Ah, I didn't catch that you didnt even have it fully mounted. Much worse so being a partially connected solid mount setup - realistically you ran just as much risk starting in P/N of cracking the case. That aluminum is pretty thin and isnt made to carry loads like that. At least with stock style rubber lowers, the whole powertrain can flop back and forth if the uppers aren't hooked up.

Did you delete your uppers completely?


This isnt intended to come off as rude - but does it seem like maybe you're trying to tackle too many things at one time? I get you want to end up with this crazy one off race car at the end, but your current predicament sounds pretty absurd for trying to test drive the car:
-engine not running right / throttle wedged open
-starting with trans in gear
-engine mounts not hooked up

Since you dont even have a turbo on it yet maybe youd be better off putting the 4t65 back in, get it running in stock configuration, then start adding the mods one at a time so at least its drivable? Just seems like you're having to cut a lot of corners rigging stuff up temporarily to try to make this work at all.

 

I did delete the upper dog bones. They wouldn't have worked as the custom engine/trans mounts shift the mounting points pretty drastically. Plus I wanted them gone for exhaust install/removeal, and ease of changing plugs.

The testing I'm trying to do currently is basically just seeing if the 4t80e functions as it should. I'm not entirely concerned about the engine running properly, as the engine in that car wasn't right to begin with. The only thing that concerns me is that it wont idle, which you've hinted me towards a posible fix. I wanted to test the 4t80e swap in this junk car first, as proof of concept, then swap it to my daily and continue with the turbo kit.

Also, the aurora with the N* and 4t80e doesn't have upper mounts, it has drivers trans, passengers engine, front trans, and rear trans rubber mounts

 

It's still going to take time, and a lot of work, but I'm slowly nearing the end of this journey. As far as the turbo kit goes, I'm piecing together the intercooler kit. Ordering parts from ebay, amazon, tial, and mishimoto. I have lots of other parts waiting to be put together. The most work I still have left is with the hot side. I haven't had the time to weld everything together yet. It's also 95* all day here in Texas, so that doesn't help either. As far as the trans repair goes, I have a replacement for the part of the case that I cracked along with the gasket. I just need to make time in order to get it installed. I'm going to disconnect the steering rack, shocks, and subframe so that I can just use the engine hoist and lift the front end of the car up high enough to access the trans.