Mechanics

#1 AND #4 CYLINDERS NOT FIRING

1997 Saturn SC2

Computer problem
1997 Saturn SC2 4 cyl Two Wheel Drive Manual 199000 miles

#1 and #4 cylinders not firing. Thought it was the coil (since there are 2 of them) and it did not fix the problem. I switch the coils only to have the same results of #1 and #4 not firing. I then replaced the module hoping that it was the problem. Well. It did not fix it. I am not very familiar with Saturns ( I was a Honda Tech) so I do not even know where the PCM is located. Is the PCM the next thing to replace?

I am going to borrow an OBD to pull the codes later, but if anyone has experienced this delima, I would appreciate any help!
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HondaMike
April 30, 2010.




The PCM is the last thing I would replace they hardly ever go bad on those. It's located under the dash on the driverside if u look up under there u can see the connectors. Get a noid light check both the number 1 and 4 injector connectors for signals while it's running. Also perform a compression test on all the cyls and let me know what they were. Also let me know if there is any codes.

Saturntech9
Apr 30, 2010.
Got plenty of compression. I got a code PO340 - but this does not have a cam sensor. So I believe it is the result of the misfire, not the cause.

Tiny
HondaMike
May 4, 2010.
The most likely cause of ur p0340 its usually wires and plugs they get this black carbon on the wire ends wire they meet the plugs the plugs also the coild towers get corroded up causing the code p0340. Thats strange ur number 1 and 4 cyclinders dont fire but u dont have a p0301 or a p0304 or even a p0300 random missifire. Does ur number 1 or 4 fire at all?If u pull each wire off and put it back on one at time do u loose rpms?Also is ur 1 and 4 coil sparking at all?Did u see if u have injector pluse signal to those injectors?Let me know.

Saturntech9
May 4, 2010.
Replaced all wires and plugs. I even swapped the coils only to have #1 and #4 still not fire. I pulled the plug in #1 and it smelled of gas, so I assume that it is getting fuel. The other item I am going to check is the crank sensor. I was thinking if the crank sensor was bad, it would not run at all, but.

Tiny
HondaMike
May 4, 2010.
Ur right if the crank sensor was bad it wouldn't run at all or it would run warm up then die. So if u take off ur 1 and 4 wires off ur coil and crank it over does it spark from post to post?If not let me know.

Saturntech9
May 5, 2010.
No - it does not spark from post to post with the wires off.
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Tiny
HondaMike
May 5, 2010.


http://www.2carpros.com/forum/automotive_pictures/416332_1997_sc2_p0340_part2_1.jpg


i would follow that p0340 trouble tree i posted for u that looks like the problem ur 1 and 4 signal to ignition module.i also posted wire diagrams and circuit description.let me know what u find.

Saturntech9
May 6, 2010.

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