Lexus IS300 won’t start after transmission and engine swap

i did a auto to manual swap
changed the wiring harness inside and out including the ecu etc and i threw the manual motor/transmission onto my vehicle but only my lights and electronics work. car won't even attempt to start or sputter or anything. what can cause my car to not start?
i changed all my fluids, and belts as well. i made sure i didn't mess with timing on the timing belt and kept it to how it basically was (which was properly timed)

My car has 158490 miles.
My car has a manual transmission.

Experienced mechanics share their insights in answering this question :
There are countless reasons your engine might not run after a swap like this. One thing to keep in mind, however, is that an engine needs three things to run: spark, fuel and compression. Checking for each systematically will help narrow down the potential causes for your concern. Spark can be checked with an inline spark tester. Fuel pump operation can be checked with a fuel pressure tester and fuel injector control can be checked using a noid light. Finally, compression can be checked using a compressor tester and/or a leak down tester. Diagnosing your vehicle’s no-start condition could be very difficult and time consuming. If you’d rather have a professional tackle the job, keep in mind YourMechanic comes to your home or office. We would be happy to diagnose and repair your no start condition.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most common reasons a Lexus IS300 won`t start are a dead battery, an alternator problem, or failed starter.
IS300 6speed conversion kit uses any Nissan 350Z 370Z G35 G37 VQ Transmission to install the Manual Gearbox into the Chassis.
This engine produces a maximum power of 214 PS (211 bhp – 157 kW) at 5800 rpm and a maximum torque of 288 Nm (212 lb. ft) at 3800 rpm.
The real meat is in the sedan portion of the marketplace, which is why Lexus introduced a five-speed manual version of its IS300 sedan, hoping to gain more of the serious sports-sedan crowd, which usually goes for BMWs but who might want a Lexus instead because of the Japanese brand`s famous build quality.
The most common reasons a Lexus ES350 won`t start are a dead battery, an alternator problem, or failed starter.
The most common reasons a Lexus IS350 won`t start are a dead battery, an alternator problem, or failed starter.
The 2JZ-FSE is always used with an automatic transmission.
The IS300 uses the same 2JZ-GE 3.0-liter DOHC 24-valve straight-six that propels the bigger Lexus GS300 sedan, an engine that traces its lineage to the old Toyota Supra.
Transmission fluids in newer Lexus models can go much farther than those in older cars. However, while some newer cars have “lifetime transmission fluids,” what this really means is that the fluids will last through the lifetime of your car`s warranty.
The 2021 Lexus IS 300 has a 143mph top speed, a remarkable feat.
The most common reasons a Lexus IS300 key won`t turn are a binding steering column/lock, an ignition switch issue, or a problem with the ignition key.
Toyota Soarer / Lexus SC300. Toyota Supra.
The most common reasons a Lexus IS300 key won`t turn are a binding steering column/lock, an ignition switch issue, or a problem with the ignition key.
Starting problems/ irregular idling

The IAC (Idle Air control) valve and the EGR (Exhaust Gas Recirculation) valves are prone to getting blocked up with a carbon build up. If you are having problems starting your vehicle and/or you are having irregular engine idling, these parts need to be cleaned out.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

The car crank but won’t start
ANSWER : Hi there. This does sound like an issue with the wiring. If the check engine light is coming on every now and then this means that when it does not come on there is no power to the computer. This can be the wiring harness issue or an ignition switch problem. I would have to test for voltage to the computer when the problem is occurring to be able to find where the issue lies. If you need assistance, a certified YourMechanic technician can be dispatched to your location to inspect your vehicle’s non-start issue and suggest any necessary repairs.

Car won’t start. The check engine light, battery light, and oil change light are coming on. I tried jumping the car and nothing happened. Why won’t my car start?
ANSWER : Hi and thanks for contacting Your Mechanic. If sometimes your vehicle will start with the new alternator and sometimes it won’t, then there is a loose connection in your charging system. Check all of the wires to the alternator and to the battery. Make sure that the battery cables are clean and tight. Make sure that the wires to the starter are clean and tight. A loose ground to the ignition system will cause the vehicle to not crank over. Check all of the ground wires from the battery to the starter. Make sure that they are clean and tight. If you need further assistance troubleshooting your no start situation, then seek out a technician, such as one from Your Mechanic, that can assist you.

Vehicle won’t start, once it’s jump started it only stays running until you turn it off, then it work start again without jumping.
ANSWER : Hi there. There could be two problems here. It is possible that your battery is bad and will not take a charge from your alternator while driving. In that case every time you shut your car off you will not have enough juice to start it again. Inspect your battery – it should have at least 12.5 to 13 volts to start your car, if it doesn’t you will need to replace the battery. The second problem could be that your alternator is bad and not charging your battery, in this case you will need to replace your alternator. Both the battery and the alternator can be tested in your car. If you would like to have the car checked for you, a certified professional from YourMechanic can come to your car’s location to diagnose the starting problem and proceed with repairs.

My polo 3 won’t start when engine is warm or exposed to the sun for a long time
ANSWER : Hi there,
The problems you are having with your vehicle, may not be easy to diagnose. Apparently, under hood temperature and ambient temperature both create the no start condition. Components can act-up with temperature change. Assuming no check engine light is on. The no start condition will have to be duplicated and inspected at the time of no start. This will help identify what is wrong. So many things can keep the vehicle from starting. I recommend having the vehicles no start condition be inspected and diagnosed by a certified technician from YourMechanic.

Lexus IS300 won’t start after transmission and engine swap
ANSWER : There are countless reasons your engine might not run after a swap like this. One thing to keep in mind, however, is that an engine needs three things to run: spark, fuel and compression. Checking for each systematically will help narrow down the potential causes for your concern. Spark can be checked with an inline spark tester. Fuel pump operation can be checked with a fuel pressure tester and fuel injector control can be checked using a noid light. Finally, compression can be checked using a compressor tester and/or a leak down tester. Diagnosing your vehicle’s no-start condition could be very difficult and time consuming. If you’d rather have a professional tackle the job, keep in mind YourMechanic comes to your home or office. We would be happy to diagnose and repair your no start condition.

My car won’t start, neither does my auto. Start. Sometime it might start if I jump it sometimes it won’t.
ANSWER : Hi there. There are a number of issues that will make a car hard to start. Everything from the electrical system to the fuel system to the actual starter itself can be the problem. Finding the root cause of a hard starting engine can take some investigation. Ignoring a hard starting issue can further damage the vehicle, which will often result in a more expensive repair. You might want to have a mobile mechanic complete a car is hard to start inspection so they can pinpoint the source of the issues you’re having and recommend the right repairs be completed.

Fuel pump engages. Batery good, alternator good volts, jump start helps when wont start. Temp does not matter. Intermittent?
ANSWER : Hello. Thank you for writing in. There are several reasons your vehicle may only start when jump starting. The first and most common is a build up of resistance that is causing you to need a boost of voltage to get the engine started. This may be due to poor battery cables, a bad ground connection, a poor starter solenoid, and a couple of other issues. The first thing you want to do is perform a visual inspection of the starting system. Make sure there is no corrosion build up in the battery cables. You can also check the resistance across these wires and make sure you have a solid connection between components. You then want to make sure the starter solenoid is doing its job. It is responsible for taking the small amount of electricity sent by the ignition and turning it into a huge electrical charge that is strong enough to push over the engine with the help of some gear ratios in its favor. Do some more testing, and stick to the basics before assuming its something seriously complicated.

The car is having trouble starting up ,70 percent of the time it starts right up. the other 30 percent, it randomly won’t start its
ANSWER : Hey there thanks for writing in about your 1998 Honda Accord. This could be a few things. A faulty ignition switch, a failing crank sensor, or possibly other faulty sensors could be the cause. To have this taken care of, consider having a certified technician, such as one from YourMechanic, come to your car’s location to diagnose and repair the hard start issue.