My 03 coup has always been very healthy... after a hard take off from a red light. The engine just turned off and all dash lights started flashing. As I roll to a stop it to try to restart my car it fires but as rpms drop to an idle engine shuts off. No error codes. 1st mechanic questioned the fuel pump, tested it and tested fine. Was able to bypass fuel system and spray accelerant directly into motor and keep running. Very rough but still running.Second mechanic (Infiniti dealership #1) completed wet/dry compression test, numbers where good. But had to pull 2 ignition coils and replaced with working car same issue car would fire then shut off. 3rd mechanic (Infiniti dealership #2) is saying 1 dead cylinder need new engine but I'm not convinced or sure how they made that leap to needing a new engine.

 

Do a compression test again to see if there really is a dead cylinder.

Pull all the spark plugs and inspect.

Does the tach move when cranking? It sounds to me like you have a cam or crank sensor going out.

 

is it possible to have compression on a dead cylinder? The rpms do go up be sputtering out. If it was a sensor wouldn't that throw a code? Again no codes where coming up. Already replaced bank 1 as I thought the same thing after some research. How could the by pass of the fuel system keep the car at a rough idle tho. Which would give me the assumption the engine has enough fuel to fire but to keep running

 

I have no idea what "bypass the fuel system" even means tbh. Sounds like a "bullshitting the customer" scenario.

A dead cylinder isn't going to have the same compression as the other cylinders, doesn't need to be NO compression but it will be quite a bit less than the others, what were the results of the last compression test? If they didn't give you ACTUAL NUMBERS then I wouldn't trust them. Take pictures of all your documentation and post it, they always give you a diagnostic report at the dealerships.

Also, they did scan it with an OBD2 scanner yes? Just because the CEL isn't lit doesn't mean there aren't codes. Right now when you go out and try to start the car it will run, but run very roughly, and struggles to maintain rpm right? And it sounds like it's missing on a cylinder right?

I would get it running again, unplug the coil pack harnesses one at a time until you isolate exactly which cylinder isn't firing (the one you unplug that doesn't make any difference in the way the engine is running). Pull the spark plug and look at it for anything out of the ordinary and then replace it AND the coil pack just to verify it's not some internal failure that you can't see.

To test for fuel pressure requires a sandwich adapter like the one Z1 Motorsports sells, this engine does not have a fuel service port so you need to add one.

https://www.z1motorsports.com/z1-pro...rt-p-9160.html

 

Let's examine your information. The first mechanic suspected a faulty fuel pump (which with no codes I would have too), it tested fine (assuming he was able to read pressure and measure amperage). Then he kept the engine running by directly spraying the intake (it would run rough due to the type of fuel used and the lack of a normal fuel/air mix going into the cylinders). So the question to me is what is the problem between the fuel pump located in the gas tank and the inlet side to the injectors? That is where I would be looking. Remember, it requires air, fuel, compression and an ignition spark to run - you appear to have 3 of the 4 elements required.