90K miles, check engine light will come on after a"bump" is felt as if engine was switched off & on and light will go off later, 5 mins, 2 hrs or a day later. Lately (sometimes) it spins and spins when trying to start when other times the engine barely turns over one revolution before starting. Sometimes when accelerating it will act as engine is being turned off and on. Any ideas?

 

I had something similar in my 99 300M and it was a bad connection to the ecm.

 

any codes in the computer?

 

How do you get the codes?

 

You can do a key dance.....turn the key on and off 3 times ( don't start the car ) and any codes will appear in the odometer screen. Have a pen handy as there may be a few. Or you can stop in at Autozone or someplace like that and have them get the codes for you.

 

p1684 & p0340 are the codes. Thanks!

 

Cam sensor P0340 Replace it with an OEM one. Aftermarket sensors do not last.
Other code battery disconnect in the last 50 starts. Clean all power connections from battery to jump post and ground connections.

 

If you have any auto wreckers near you, I recommend getting a couple of used sensors from 99-01 cars. After 02 the sensors were made in China and had issues. If you get a new one from a dealer it will more then likely be Chinese.

 

Thank you very much, EVERYBODY! The cam and crank sensor in the car now are from O'Reillys and NAPA. I have one here on my desk that was removed from the car when I replaced with the others but I don't know which one it is. A number on it is:04609086 and under that is :3188

 

Big word of advice....LHs don't tend to like aftermarket sensors. Hence why Firem said OEM and I agree 100%. They are usually cheaper and easier to get but don't be surprised if you have the same issue not too long from now.