# 98 740il suddenly shuts down...



## nuttybgc (Mar 14, 2008)

From time to time, my 98 740il will shut down automatically while still running and won't start until after a while. Any one knows anything about it or has had this problem before?


----------



## TerryY (Jul 20, 2003)

Check the crank position sensor and the cam position sensors. Either one can cause that to happen.


----------



## nuttybgc (Mar 14, 2008)

So there's really nothing wrong with the engine, just the censor going crazy?


----------



## TerryY (Jul 20, 2003)

My older E32 740 would occasionally just stop running, sometimes at full throttle other times at idle.

Restart might take 3 or four tries or it wouldn't start at all for a day. Then it would just pop right off on the next try.

Crank position sensor was my problem. Replaced it and had no more problems.

If something is mechanically wrong in the engine itself it is usually accompanied by loud noises or failure to rotate anymore. Failure to rotate usually has it own noises as it reaches that point.


----------



## nuttybgc (Mar 14, 2008)

Could this be the reason causing the check engine light to illuminate? Because some days the check engine light would come on and then in a couple of days it would go away.


----------



## dannyc9997 (May 15, 2008)

nuttybgc said:


> Could this be the reason causing the check engine light to illuminate? Because some days the check engine light would come on and then in a couple of days it would go away.


Defenetly sounds like a CPS. But get the codes check anyways to confirm. Itll also tell you if its intake or ex. side


----------



## nuttybgc (Mar 14, 2008)

dannyc9997 said:


> Defenetly sounds like a CPS. But get the codes check anyways to confirm. Itll also tell you if its intake or ex. side


Is CPS short for Cam Position Sensor or Crank Position Sensor? Which one is it?

And how do you get the codes anyway? Do I have to get some kind of tools because I read a thread in here and a member in here wrote you can get the code by doing this...

"Originally Posted by Sean McClellan 
next time when the check engine light comes on, turn off the car, turn the key to the on position and then fully depress the gas pedal all the way down 5 times within 5 seconds. If there is a problem that the OBD detected it will display a code on the screen. That is a fault code. If it gives you some codes, look them up on the internet and it should tell you what the OBD had detected. Just thought I'd let you know."

But I didn't know if I was suppose to press/hold on to the gas pedal or let it go but I tried letting go of the gas pedal and pressing/holding on to the gas pedal but either way no codes came up for me.


----------



## TerryY (Jul 20, 2003)

Should be somewhere in here http://www.e38.org/


----------



## dannyc9997 (May 15, 2008)

nuttybgc said:


> Is CPS short for Cam Position Sensor or Crank Position Sensor? Which one is it?
> 
> And how do you get the codes anyway? Do I have to get some kind of tools because I read a thread in here and a member in here wrote you can get the code by doing this...
> 
> ...


Well it could be a cam or crank sensor. Your e38 has OBD2, the method you quoted would only work on an OBD1 car (pre 1996). For your car you need a diagnostic scanner. If you live in California your only option is to take it to a shop for diagnosis, or buy a scanner (can be had at autozone cheap) and read the codes yourself. It plugs in under the wheel, youll see a panel that comes off. Any other state and autozone would read the codes for you for free, but a law was passed there banning that practice.


----------



## crewdog843 (Mar 15, 2006)

If your CEL/SES light comes on....there is a reason for it...and it is always emissions related. You can buy a Peake tool and try to read and make sense of the diagnosis, or you can take it to a good independent who, for $45 or so, will not only diagnosis the problem but, like mine, will provide a printout of why your car is throwing the light. You don't have to have the work done there (if you are good with tools). 

My two experiences with the SES light on my '01: First time (45K miles), blinking....left bank cam position sensor (car ran fine the entire time). Second time (just recently 85K miles, car ran fine as well), SES steady, too much crankcase vacuum causing lean condition caused by failing OSV (no smoke yet). 

Many times the SES will illuminate for simple things like not making the gas cap click. Other times it will be a crack in one or more of the hoses leading to the intake manifold, but the car will run just fine. Your symptoms point to a more serious condition wherein the engine shuts down with difficult restarts. Get it to a competent indy before throwing any more money at the problem.

jake


----------



## nuttybgc (Mar 14, 2008)

Thanks dannyc9997 for clarifying that up for me and everyone else's input on this. It's really helpful.


----------

