Starts and runs for 3 seconds

Get this, I replaced the intake gasket, it did have one, but it didn't look like it was sealed in there.
Then I tried starting it up - would not start?
Everything was plugged in - but now if I unplug the the MAF the engine will start and run - not for exactly 3 sesonds like before - but for 4 or 5 seconds - a couple times it ran for 6 seconds.
So now, MAF pluged in - engine will not start.
MAF unpluged - engines runs for 4 to 6 seconds.

Hi KHLow2008,

A friend of mine had a 2001 Santa Fe in his shop last weekend just for a tune up. He said I could use it as a test vehicle - but the guy was coming to pick it up in about an hour - so I had to have it put back together real quick.

I did get to swap my MAF into that car - that engine would not start with my MAF installed, however that engine did run just fine without its own MAF installed - which tells me that my MAF is bad - but I also reasoned that MY engine should also run (same as the other one) without a MAF installed, and it does not, which caused me to reason that there was still another problem somewhere.

I wanted to install that MAF in my car, but I did't have the chance due to that fact that the owner was coming to get his car.

I agree that I need a new MAF, but I want to make sure that I find the real problem before I go and give the dealer my right arm again.

I'll go check the TPS readings now.

TPS has 3 wires going to it:
With the key ON;
Green - Ground
Red - 5V
Orange -.77V at idle to 4.38V wide open

Hello gentlemen, I appreciate your concern, thank you!

As you suggested, I disconnected the alternator and started it up - the engine ran for exactly 5 seconds.
The battery is brand new, and the terminals have been cleaned to the metal, they have a solid connection to the battery.
I disconnected the exhaust pipe from the CAT at the bottom of the engine - it ran for 5 seconds. Then I took the exhaust manifold off of the head and started it up. It sounded like one of my neighbors cars that he drives on the weekends..... Sorry that's another story. Anyway, the engine started, but still the same thing - it only ran for five seconds.
When I started working on this car last month it ran for exactly 3 seconds every time. Now, after I've replaced as many parts as I have, it has a variable run time (4 to 6 seconds, most of the time it is exactly 5 seconds).
My conclusion is that it must have a problem with one of the sensors that is absolutely necessary for the computer to keep the engine running? Those being the CPS, CAM, MAP, or Ignition Failure sensor (all are new, CPS is the second new one). As far as I know if there were a problem with any of the other sensors, the engine would run poorly - but it should still run.

I went and bought a scan tool this morning.
It does have code 0340 - CAM sensor.
. That was my first guess, and the very first sensor that I replaced when the problem started (just beacuse it was the easiest one to get to, and the probability seemed to be in my favor to replace it).
I'm looking for a way that I can test this one before I go and order another one?
There is a key on the end of the cam (for the CAM sensor to read) - I thought maybe it was broken, or loose or something - but it'is tight, it's not broken, and it only mounts to the shaft in one position.

Two weeks ago the engine was running (for 3 seconds) with all the sensors plugged in. Last week the MAF died (engine would not start with MAF plugged in).I unplugged it and kept looking for another problem. Yesterday, after I hooked up the scanner and got the code. The engine would not start. As of right now, both the MAF and CAM must be unplugged to start the engine (runs for 4 seconds). The online Hyundai manual says that the CAM sensor should have a 12v supply (checked it - it is there, and it is good) it should also have a ground supply (checked that also - it is good) and lastly the signal feed to the computer should send an on (5v)/off (0v) signal to the computer. I'm only getting a.10v signal coming from the sensor. Three weeks ago, I did have a 5v signal coming from the sensor - but the engine was still only running for that same 3 seconds?
I'm just going to through a new sensor in there first, and if that doesn't get the thing running, I'll pull out the computer again and see if that signal wire from the CAM to the ECM is clear.
. Was just reading that the ECU does have a 4 second time limit to get a signal from CAM. The manual doesn't say exactly what the ECU will do if it does not get a signal.I'm going to guess that it SHUTS the engine off if it doesn't get the signal?

For what its worth, my other car is a 2001 Elantra - no MAF on this car, and I unplugged the CAM sensor just to see what would happen. Well it runs just fine! Like as if it doesn't need that sensor at all!

NO! You are replacing a bunch of things when you don't know if it is the problem or not! You either have a vacuum leak, a problem with timing or your injectors are not properly firing. If you are able to initially start the car then your CPS is fine, at least for the moment. Remove the ducting to the throttle body, buy a bottle of carburator cleaner and have an assisstant crank the engine while you give the car artificial gas and tell me how long it runs (keep it running with the throttle partially open). If you have a fuel pump reset button then follow the steps to reset this just to be sure.

How about you not make the guy go out and spend $400 on a buch of computer equipment when he can't get the car to start and run. If he was experiencing stalling or a rough idle then that would be different, however a car that runs for 3 seconds is starved for one of 3 things, fuel, spark or vacuum. Why don't you guys start with things that are intuitive, inexpensive and that MAKE SENSE first before you start telling someone to start replacing expensive components that you have no clue on how to test. Nobody even bothered to ask the guy if he used an OBD II tester to see if it threw codes at him.

To merlin boy:

My point was to check things that were obvious and simple first before dashing into blamming the ECU. A vacuum leak, fuel or basic timing issue is much easier on the wallet to fix than an ECU.

Ok so the guy went out there an timed his running engine with a stop watch?

Ya thanks I am a computer engineer and I understand how the system works.
The computer is pre-programed with the firing order. IT DOSENT JUST CHANGE THE FIRING ORDER HOWEVER IT WANTS TO. The CPS sensor is a hall effect sensor which is signaled to fire by a rotating magnetic ring on the flywheel or the crankshaft front balancer. This causes the breaking current to the ignition coil pack. THE ENGINE WOULD NOT FIRE IF IT FAILED!

The fuel pump is always under pressure if the ignition is on! If it isn't then your fuel pump is failing.

I didnt suggest cleaning the throttle body moron. I said give it artificial fuel and see what happens. If the car runs as long as you have fuel and then sputters and dies then you either have a major vacuum leak or fuel issue. If it still dies as you say then it is exclusively a timing issue. IT HELPS NARROW THINGS DOWN AND ELIMINATES OTHER POSSIBILITES!

IF YOU WANT TO BAN ME FINE BUT I HATE PEOPLE WHO DON'T TAKE THE TIME TO ELIMINATE OBVIOUS POSSIBILITIES.

And for the person who's post and car this is: I appologize for the aggrivation. I do not consult or have a team, I do this on my own and I may not be as professional as the master mechanics here, but I hope you take my considerations. If they are completely wrong then my fault.

As I stated before I was trying to offer "free/ inexpensive" proposals to try first before immediatly jumping to a conclusion on something different; you think the guy is going to come back if he replaces the ECU, cam sensor or his fuel pump and still has a problem?

And no I completely disagree on the fuel pump. The pump will run as long as the ignition is on until the proper fuel pressure is maintained. It has nothing to do with then engine firing or not. If you don't believe me go take an injector out and turn the ignition on. You will drain your tank out of that port, whether the car runs or not.

I made my suggestions. Look at all my posts, I have made possibly 5 out of 50 bad diagnosises. If you want to add this one to it then that is fine, I don't have a problem being wrong.

I looked into the matter further and the cam sensor does indeed specifiy the cylinder to fire, while the crank signal specifies when to fire. I am not sure why Hyundai engineers would bother with a variable timing order. My only guess as to the reason for this would be that if you happened to turned the engine with the CPS out of position you would change the timing. A cam sensor would not allow for this to occur. If I am correct then when the ignition is on and you sweep a magnet passed the CPS sensor at the correct distance a spark plug should fire. IF YOU DO THIS AND IT WORKS THEN YOU NEED TO MOVE THE TIMING BACK TO TDC AND MAKE SURE THE CPS SENSOR WILL FIRE ON THE #1 CYLINDER. My guess is it will not since the cam sensor decides which is the correct cylinder to fire. If you decide to replace then change out the CAM sensor, CPS sensor and then the ECU in that particular order.

Again I appologize for the incorrect diagnosis.