I have a 2000 S40 Turbo with around 200,000 miles. I have been plegged with problems. I have changed everything from Crankshaft Pos. to Camshaft Sensors. I have done oil changes and coil packs...and everything in between. I also come to discover a Turbo was bad, so it was replaced also.
After all is said and done, I was getting a pretty good running car, driving and running fine. But park the car for any amount of time, and come back later only to find the car with NO power. Barely turning 400-500 RPM's....and as soon as you mash the gas it shuts off! Come out a day or two later, turn the key and it runs fine again. This can happen at anytime...sometimes once or twice a day!
Why would this car runs fine one second , then the next time you try and run it, it has NO power??!!!! Never sure how it will run when you turn on the car. Thanks in advance for any advice.

 

Is the alternator warning light out when this happens? Just wondering if maybe the battery is weak (or loose/dirty battery cables) and it takes the alternator coming online to run correctly. Just a guess.

 

Thanks Hudini,
Come to think about it...the battery is a little week from sitting, while I have been doing repairs. I had to jump the car off, right before I put on the Turbo. I will try a better or new battery and see what happens.
Would this still be something that would do the "on and off" again problem? I have even cranked the car, watched it run great.....shut it off and restarted the car (only to have it do my problem)...then restart the car, for the third time... and have it run great again! Its really quite crazy how it does.

 

Your description does sound like a loose or corroded cable or similar bad connection problem. I've seen some weird behavior associated with low voltage. Try wiggling the battery cables and grounds the next time it happens just to see if it's a loose connection.

 

Update......I just put in a brand new battery, and cleaned the cables. It spins over fine and has a good connection. It didnt start at first, then after about 3-4 minutes trying...it started. It ran fine, and restarted a few times after this. Then, it started my problem again.
It will do this all day long, never knowing which "key turn" will bring on the problem. I did notice that on one of my good turns, it almost didnt crank...and then sputtered, then cranked up...running fine. I am thinking it has to be some sort of electic/sensor deal???....When it runs , it runs good....Any idea guys??

 

Hey Guys...got an update. I finally got a code reader done on the car. It shows two codes, and one thing that looks strange. My codes are...
PO340 Canshaft Pos. Sen. A (Bank 1 or single sensor)
PO335 Crankshaft Pos. Sen. Circuit Malfunction
also...on the reader it said "Fuel System Statues Bank 2 Disabled" ???

I have replaced both the Camshaft and Crankshaft Sensor...Any thoughts??

 

New update....I have not tried a ignition mod yet, but I did notice that when I unhook the battery, I can get the car to start correctly. I usually wait a minute or two, and let some of the dash lights go off. It has started every time I have done this, but when you shut it off and try to restart...it does my problem of not starting like it should.....Maybe this is just a coincidence, or another step in finding out my problem???