Saturn LW 300 runs fine for a few miles then stalls no SES Light

[Firestarter]

I have a 2002 saturn LW 300 that was running great untill the other day. We were going down the road and the car stalled with no service engine soon light. Changed the fuel filter since I bought the car used and don't know when it was changed last. Car ran decent for a few miles then stalled. Let the car sit over night and started it up and went a few miles and it stalled. Still no light indicating a problem. We got gas the first day it stalled so I am wondering if we got some bad gas. Is there anything besides the fuel filter I should be checking since there is no SES light?

[fdryer]

Yes and no. The crank position sensor (CPS), next to the oil filter can be tested in two ways; a spark test or removal from the car for bench testing. No spark testing can be done with our wireless plugs so removing the cps for bench testing is needed.

Once removed for bench testing you'll need a multimeter to measure resistance, cold and after immersion in boiling water (replicating a warmed up engine). Resistance will be between 700-1200 ohms for a good one. Once heated close to operating temps, if the resistance disappears as an open reading then the cps is faulty. It should operate in all temperature conditions; from below freezing Artic conditions to the high temps of Arizona deserts. Engine heat goes well above 200F so yours may be intermittent as many have found on this forum as well as the S-series forum. Most auto stores should stock it.

[ernesto rex]

A vehicle that dies after warming up, restarts after cooling down and displays no service/check engine lights would make me suspect a failing crank position sensor (CPS). The usual test for such things is to remove the sensor (it is located in the engine block right next to the oil filter canister) and warm it up in a pot of water on the stove.

My wife loves it when I do this.

Anyway, the sensor will read some resistance until it warms up and then it will read like an open circuit (broken wire).

[Firestarter]

Worth a try. I will check that out. That would really stink since I replaced that less than two years ago. But back then it gave me a service engine soon light untill I replaced it.

[Firestarter]

Thank you for the info.

[Firestarter]

Would the CPS malfunction withought making the SES light show up?

[bluesl2]

The cps failure probably will never turn on the ses light, of course it will come on though after the engine stalls out. This is classic signs of cps failure though, just change it and be done with it. Don't assume that for every time a vehicle has an issue it's going to turn a light on.

[Firestarter]

Worth a try. I will check that out. That would really stink since I replaced that less than two years ago. But back then it gave me a service engine soon light untill I replaced it.

[Firestarter]

Ok. Was just checking to be sure. Since the part is order only and no refund. What wires on the sensor do I check?

[Firestarter]

Worth a try. I will check that out. That would really stink since I replaced that less than two years ago. But back then it gave me a service engine soon light untill I replaced it.

[Firestarter]

Firuged out what wires to check. I brought warm water to a boil left it there for a while then let it cool off and no open circuit.

[Firestarter]

Worth a try. I will check that out. That would really stink since I replaced that less than two years ago. But back then it gave me a service engine soon light untill I replaced it.

[Firestarter]

Anything else I can check besides the CPS. Maybe just a bad batch of gas?

[fdryer]

Everyone loves to blame a bad tank of gas until a caravan of cars sputtered off the side of the road on the New Jersey Turnpike a year or two ago; diesel from a tanker truck inadvertently filled the wrong underground tank. Although it can be suspect, any car that has been filled with bad gas cannot be the only car to have bad gas; every car filled from the same pump has to be filling up with the same fuel and should be mysteriously leaving cars all over town stranded with the same symptoms.

You can perform a real world fuel and pressure test easily (without a fuel pressure gauge); turn on the ignition and listen for the faint hum/hiss sounds of the fuel pump running for 2-3 seconds, shutting off from the ecm timer, locate the fuel rail's test valve covered by a large black plastic cap, remove the cap to reveal the schrader valve (resembling a tire valve), cover loosely with a rag while depressing the valve stem expecting a healthy spray of fuel. Fuel and spray means the entire fuel system is operating and pressure is available to the injectors. Pulsing the injectors is the job of the ecm. Guess who controls the ecm? The cps provides precise timing signals to allow the ecm to operate; turning on the fuel pump, ignition system for spark, and pulse the injectors. No cps output = no fuel pump, no ignition for spark, and no injector pulses.

When you perform a simple fuel and pressure test you confirm the fuel system being operational. This verifies 1/3rd of ecm operation. Spark and injector pulses are the other 2/3rds of ecm operations. Removing the spark plugs to perform the old school test for an actual visual verification of spark is difficult to say the least so the cps test is the alternative test that gets to the heart of the matter. If the fuel system operates by spraying fuel then its virtually confirming ecm operability. It will not confirm the ignition system or injector pulses since these are dependent on the cps timing signals whenever the engine rotates.

[Firestarter]

I tested the CPS for quite a while. Brought the water to a boil while testing it then let it cool and no open circuit while testing it.

[fdryer]

Oh-oh, this looks serious. Usually its the cps that faults out in many similar descriptions so there's more work to do with a good cps. You'll have to turn your attention to the fuel system, specifically the fuel test valve to gauge pressure. With or without a pressure gauge.

Go back to post #14 and perform the fuel test as it becomes important now to see fuel spraying out the valve.

The cps not failing in heated water is loosely interpreted as; the timing signals generated from engine rotation is used to turn on the ecm that runs the entire EFI system - turns on the fuel pump, runs the ignition system for spark, and pulses the injectors.

[Firestarter]

Update: Took care for a drive got it warmed up nice then took it for some driving up steep hills and not one problem. When I pressed that valve I had to have a rag there because it really shot out and it took a while for it to stop spraying soaked a couple rags and a good part of a pant leg on a pair of pants. The filter was really dirty.

[Firestarter]

It finally quit again. It almost feels like it's stalling out loosing poser before it actually quits. With the cps it just quit suddenly. This is a loss of power then finally quits. But this seems like there are so many parts that could be acting up. Anyone know of the order I should check all this stuff to diagnose what is happening.