Mechanics

PROBLEM

1992 Saturn SC2 • 4 cylinder 2WD Manual • 211,000 miles

1992 saturn, showed code 48, I changed the knock sensor, and still had he same problem of it stalling when warm and not starting until cooling down. I was told it is probably the pcm. Anyhow, the car is now only firing on 2 cylinders (1 and 4) I am going to change out the pcm but I wonder why it only fires on 2 cylinders now. Can anyone help me out?
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Carnivore
May 10, 2011.




Before you go changing the pcm which I don't think it's that cylinder 1 and 4 are on the same coil and so is 2 and 3. Take the number 2 and 3 wires off the coil and crank it over while you watch for spark jumping from those two coil posts. Let me know if they spark you could just have a bad coil. Also do you have a multimeter?


Saturntech9
May 10, 2011.
Yes I do have a multimeter. I was guessing a bad coil as well but what I didn't understand was the code 48 before that indicates the knock sensor and if that didn't fix the initial problem, then I was told it is probably the pcm with that code 48. What happens is the car would stall and not start for about 15 minutes. Then while trying to figure out the first problem, this second problem of not firing on 2 and 3 started, so basically 2 problems now. And thanks for the help here.


Tiny
Carnivore
May 10, 2011.
The code 48 is for the reference signal intermittent or noisy not for the knock sensor so that code with two cylinders would go together.I posted the code description below please check for spark like asked and tell me what you find.


Saturntech9
May 10, 2011.
Ok I will try that I already have the pcm out so I will install it and try what you said. Here is a copy and paste from a site I was reading on. It is the crank position sensor not the knock sensor but I think they are basically the same thing. So heres the copy and paste: The codes 19 and 48 have to do with the crankshaft position sensor. This will cause the issue you are having with the car not starting or shutting off when warm.


Tiny
Carnivore
May 10, 2011.
Those two are not the same the crankshaft position sensor tells the pcm where the crank is and when to fire the coils and tells pcm the engine rpm tach output etc. That would cause the car to shut off and not start. But I have never seen a bad crankshaft sensor single out two cylinders and cause them not to fire. It causes no spark period when they fail or start then die right away etc. The knock sensor is just that it sense's engine knock and adjusts the the time to stop it. It has nothing to do with rpm. So do you also have a code 19?Also let me know about what is going on with the spark. You can test the crankshaft sensor when it won't start and you have no spark to any cylinder with a ohms meter across the two terminals of it. It should read about 800 ohms if its good. When they test bad they usually read as a open circuit. The sensor is to right of the starter facing straight up in the engine block.
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Saturntech9
May 10, 2011.
Ok, I checked the coil and sure enough it is not sparking. So just wondering if it is possible even though the 1 and 4 is firing but 2 and 3 is not, is it possible that the ignition module is no good? Also, could it be the pcm with a problem not telling 2 and 3 to not fire? Thanks so much for the help and sorry for taking so long, working for a living gets in the way.


Tiny
Carnivore
May 11, 2011.
Also what should be the resistance on the coil pack.


Tiny
Carnivore
May 11, 2011.
Take the spark plug wires off the non sparking coil and measure across the two coil towers it should be 7,000-10,000 ohms. Also you could have a bad module or pcm or wiring for that matter. Lets start by you getting me the coil reading and also you never my question did you also have a code 19?


Saturntech9
May 11, 2011.
Sorry no I didn't have a code 19 just code 48


Tiny
Carnivore
May 11, 2011.
Alright let me know when you get those coil readings.


Saturntech9
May 11, 2011.

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