Alright guys so today I recieved a call from my mechanic with some good and bad news. The good news, The 3gr is finally in the car! The bad news, is it won't start. We tried using both the 3gr and the 4gr ECUs and neither of them allowed the car to start. A few things to note, when trying to start the car, the engine will crank and keep cranking (without turning over) until you press the engine start/stop button again. Also, the car will start to crank if you press the engine start/stop without the brake pedal being pushed down. We scanned the ecu and got codes P0351, P0352, P0353, P0354, P0355, and P0356. So basically none of my ignition coils seem to be working. Does anyone have any idea what could be causing ALL the ignition coils to just not work (along with why I no longer have to depress the brake to get the engine to start cranking?) We have already checked all the fuses and grounds, and my mechanic rechecked all the connections to make sure nothing was left unplugged. I'm completely lost right now, and would appreciate any input that may point me in the right direction. Thanks in advance!

Ignition coils: sounds like it's not connected or a shared +12 / ground was broken or pinched. Disconnect a couple of them and ohm between the harness to find what is common. Verify this wire makes it from the coil to the ECU.

Start button: Perhaps a result of swapping the ECU but honestly, I'd guess it's something else.

Swapping ECU's likely freaked out the body control module/immobilizer. Stick with the 4GR ecu and make sure the two are paired through the initialization sequence.

That's all I've got for now.

awesome I appreciate all the info! I’ll have my mechanic check the wires for the coils and see if he can find any breaks or anything. How would I go about making sure the ECU is paired during the initialization sequence?

Look here - it discusses jumping pins 3 & 14 of the OBD port.
That said, on these cars the tacho and Speedo do their sweep.
https://www.clublexus.com/forums/is-...ability-2.html

Keep in mind for this to be successful, you need a good charger connected to the battery to sustain a voltage no lower than 12.75VDC. Ideally it's 13.2 or higher.

So I did the ecu handshake procedure and it solved the problem with the car endlessly attempting to crank. With that being said, I now have a new issue😭😭 now when I try to start the car, it does not crank at all. The key is synced to the car (can lock/unlock the car, the car asks to touch the key to start button with brake depressed if I try starting with the key outside of the car) all electronics seem to be working normal (this includes radio, head lights, brake lights, windows, blinkers, power mirrors) but the car just will not even attempt to crank. I have already checked the battery, and all fuses including fusible link. One thing to note is that the engine start button doesn’t light up green when I put my foot on the brake like it used to. Instead, it lights up and amber color. When I actually press the button, the light turns green and stays green until the button is let go of. It then goes back to amber. If anyone has any input on what could be causing this it would be greatly appreciated. My cars been out of commission for months now and I really need it working again.

Lexus tech here. Been away for awhile as my wife and my first child came down with some heart problems. Everything is better and so I'm back. Any help I can be ask away. Can i be brought up to speed real quick on something. Did the ECU and the fuel injector driver get changed out or know. The pulse width modulation all g the with cranking iac steps need to be correct. The iac needs to be with the 2 to 10 step range. Bouncing around is normal but consistently going outside of 10 or pinned at zero for sometimes seconds at a time is one issue.

I could go on and on with cranking fuel percentages and so forth but I need to know is the ECU from a 3gr or from that specific 3gr and same question on the driver's or did you try to have this install using your driver and ecu. Forget about bore diameters and strokes. Need those answers first.

First of all, thank you for the response! Secondly, all the electronics on the engine (including ecu) were transferred over from the original 4gr that came with my is250

My apologies for hijacking this discussion, Armadous1 could you please check you PM.

Thanks

Andre

Help? Ok so idk if this is the right place but maybe you guys can point me in the right direction. I did the 3gr swap from a 2wd gs300 and swapped into my awd is250 swapped oil pan all awd specific parts used the 4gr intake maf and ecu the car is cranking over but I'm not getting ignition. Throwing p0351-6 all the coils And a mass air flow code. I tried the handshake but maybe I need to do it again?? If there's anything I'm missing it would be greatly appreciated. But for all intents and purposes 2wd will swap into awd if you put in the work.

Did you leave any harness on the donor? Maybe missed a ground? Double check all those ECM connections maybe one is not fully seated?

The only thing I didnt swap was the harness from the injector driver to under the intake plenum area, I didn't want to take apart stuff if i didn't have to, could that be it? Gonna check all the grounds and retry the handshake and then ill post an update

Can you see the injector driver harness PN? Is the tag visible? Compare it to the old one and or look online and see if it's the same PN for both engines. If not, you need to know what the difference is.

So, you pulled a coil and plug, inserted the plug, grounded it, and cranked = no spark? Correct?

Very curious why all of the sudden everyone dropped the topic? What was the solution to 351-6 no start issue???

​​​​​​Sorry about that I meant to update but so far the issue was due to wiring not being plugged in correctly I had a few different hands help with the swap and eventually I took it to a different shop in my area and the tech there was able to diagnose the no start as a wiring issue something ie. something not plugged in properly in the harness but after that the swap has been solid. Running the 3gr on the 4gr ecu for almost 6 months now with no issues , I used a 2wd and swapped all the awd stuff from my original engine/car. But one thing I didn't do was swap the lower intake that has a sensor the 3gr doesn't and that is causing a check engine light but it hasn't affected driveability I am planning on swapping the 4gr lower intake and adding a rr racing oil catch can because carbon buildup was the original reason my 2.5 died. But I hope that update helps ,
tldr: If you do the swap make sure you keep damn good track of the harness and where everything goes.

Good to hear. We figured it was something like that.

Because you had the RWD <> AWD mismatch, does the front timing chain cover have to come off to do the swap? At a glance, I'm going to say no.... Just wanted to confirm tho!