2007 RDX 4 cyl Turbo AWD cranks up and runs for about 1.5 seconds then shuts off. It doesn't sputter out, it just shuts off immediately. I changed the battery with a 5 month old battery, same thing. Even put a fully charged jump box on the newer battery and it does the same thing. I can even rev it up for a second before it cuts of so I don't believe it is a fuel problem and no real indicator lights come on either. Could it be the Alternator?

 

a bad alternator would just let the battery die over the course of a day to two days.
wouldn't turn off the car in 1.5 seconds.

Something else is happening here. an engine requires air, fuel and spark to run.
it's getting the spark and fuel, as the engine starts. then it just dies.

 

Welcome to the forums.

This thread has been moved to the model specific forum for better response.

 

This has happened to me on some completely different cars, but exactly as you described. In those it was a theft deterrent issue - I want to say the car was not recognizing the key. Another thing to check - see if your key is actually staying in the run position or if perhaps the cylinder is letting the key rotate all the way back to accessory position. Ignition switch could also be a fail point that causes this. I would try starting it and holding the key turned all the way (your starter will disengage as soon as the engine fires, no risk of damage), to see if it stays running. This could help you diagnose.

 

 

 

Did you check the items I mentioned in my earlier post in this thread?

 

 

Did you ever find out what this was? My car has exact same issues and is at dealer and they dont know what is wrong?

 

^did you check what Tomtwtwtw spoke about?????

Quote:

Originally Posted by Tomtwtwtw

This has happened to me on some completely different cars, but exactly as you described. In those it was a theft deterrent issue - I want to say the car was not recognizing the key. Another thing to check - see if your key is actually staying in the run position or if perhaps the cylinder is letting the key rotate all the way back to accessory position. Ignition switch could also be a fail point that causes this. I would try starting it and holding the key turned all the way (your starter will disengage as soon as the engine fires, no risk of damage), to see if it stays running. This could help you diagnose.

 

Could it be the Main relay (main fuel relay)?

 

I had a different car, exact same symptoms: start, can rev, then immediately off.
Was CRANKSHAFT position sensor, cps, in absence or bad signal it would immediately turn off fuel delivery via the pump relay. Changed the cps myself with new one from online store, car worked without a glitch since.
》There is a different cps, CAMSHAFT position sensor, its malfunction may lead to different symptoms like rough idling, probably not turn off engine.

Your case might be quite different, assuming a dealership mechanic would find any cps malfunction in little to no time.

Hth