1992 Saturn problem

Tiny
CARNIVORE
  • 1992 SATURN SC2
  • 4 CYL
  • 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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Tuesday, May 10th, 2011 AT 10:19 PM

21 Replies

Tiny
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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?

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Tuesday, May 10th, 2011 AT 10:26 PM
Tiny
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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.

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Tuesday, May 10th, 2011 AT 10:34 PM
Tiny
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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.

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Tuesday, May 10th, 2011 AT 10:43 PM
Tiny
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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.

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Tuesday, May 10th, 2011 AT 10:59 PM
Tiny
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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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Tuesday, May 10th, 2011 AT 11:11 PM
Tiny
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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.

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Wednesday, May 11th, 2011 AT 9:31 PM
Tiny
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Also what should be the resistance on the coil pack.

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Wednesday, May 11th, 2011 AT 9:45 PM
Tiny
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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?

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Wednesday, May 11th, 2011 AT 11:15 PM
Tiny
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Sorry no I didn't have a code 19 just code 48

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Wednesday, May 11th, 2011 AT 11:30 PM
Tiny
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Alright let me know when you get those coil readings.

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Wednesday, May 11th, 2011 AT 11:33 PM
Tiny
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Ok Im getting 7100 on the one thats not firing and on the coil that is firing I get 8300

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Wednesday, May 11th, 2011 AT 11:43 PM
Tiny
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Just a guess but from the readings I am getting from the coils, they are within range but can give a different reading when heated up I know. But even when its cold 2 and 3 do not fire so I am ruling out coils and begining to think ignition module.

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Wednesday, May 11th, 2011 AT 11:58 PM
Tiny
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Its within spec lets try this swap the coil positions and lets see if the non sparking coil sparks in the other position on the module.I posted the wire diagram for the module and the trouble tree for code 19 which is for no 6x signal which is the only signal coming in for the coils to fire.A bad module would make sense for when it got hot and shut off and wouldn't all the bad module's I have replaced did that. When it got hot and died and wouldn't start did ever see if it lost spark at that time?A bad module seems correct but I don't know if it would set that code 48. Too bad you don't have a tester module to swap out.

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Thursday, May 12th, 2011 AT 12:08 AM
Tiny
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I have new coils coming in tomorrow and will put them in and see what the result is. When I see what that does, I will inform you of the outcome and go form there, so I will get back to you tomorrow and I really appreciate you helping me with this. Thank you very much! I will post results tomorrow.

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Thursday, May 12th, 2011 AT 12:14 AM
Tiny
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Dont replace the coils just try swaping there positions like I said. Dont waste the money on the coils.

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Thursday, May 12th, 2011 AT 2:02 AM
Tiny
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Ok, swaped the coil positions and it is still not firing on 2 and 3.

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Thursday, May 12th, 2011 AT 4:45 PM
Tiny
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Sorry and the non sparking coil does spark in the other position.

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Thursday, May 12th, 2011 AT 4:46 PM
Tiny
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Ok, I had a good working pcm from the same year car M/T same as my car and the sc numbers match up. So put that in to see if I had spark on 2 and 3 and again no spark. So I am leaning towards the ignition module or a broken wire. How should I check for a broken wire other then visual?

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Thursday, May 12th, 2011 AT 5:00 PM
Tiny
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Its looking like a module you the wires are good because thr other coil sparking. The way you test the wires is go from each end of the circuit with a ohms meter on low scale and you should see less then 2 ohms from one end of the wire to the other end of it.

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Thursday, May 12th, 2011 AT 10:19 PM
Tiny
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Thanks so much for the help, it was the ignition module, changed it out and running like a top now, so thanks again for your help.

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Saturday, May 14th, 2011 AT 3:05 AM

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