Hello everyone,

I joined this forum and said hello in the new member thread. I have a decent 1996 SL2 4 door sedan. I purchased it used in February of 2010, from a used car dealership. It has been wonderful! Had to replace the drive belt which I did by myself new tires, and replacing my headliner now. It started to sag so I got it out and I am working on that now... Now my baby has some codes she is throwing at me...
1) P0300- Random multiple misfire detected(intermittent)
2) P0341- Engine Camshaft position sensorA circuit
3) P0345- Exhaust gas recirculation sensor A circuit.

Two people have told me to replace the plugs & wires. A third said the same thing and also the EGR Valve... The plugs and wires are original parts and also the EGR Valve. the drive belt was original too.

Any suggestions??? Thanks for your time

Rich

 

not to familiar with the s cars, but I would go through and replace all of it if you can.

 

Dude, if those are the original wires and plugs, you are waaaayyyyyyy past due for a change. How many miles are on that car? You may get by with just removing the EGR valve and cleaning it along with the port where it is connected to the intake. Check all of your connectors for corrosion. I'd almost bet you've got some serious crap built up on the wiring harness since it seems like that car has been neglected in the maintenance department.

 

hell, id go through and replace anything I could replace if that is the case. every plug, wire, sensor etc.

 

Thank you! Are regular wires and pugs o.k. Or should I get the "Best" any ideas???

 

just don't get bosch. apparently their plugs have a bad reputation. autolite and ngks are good. wires, im not sure about.

 

If you have or know anyone with a good multimeter, then check the wires for resistance. On the resistance scale set to 1k on an analog, or just ohms on a digital, look for about 4k ohms for each wire. If all the wires test around that, then they are good and I would not replace them, but they all need to be about the same.

If you need to replace them, use OEM spec wires only. The ignition system is very sensitive to the secondary resistance (the combined resistance of the plug, wire and secondary coil winding). Many high performance wire sets have a lower resistance that will cause misfire with your system. They are meant to be used on high performance after market ignition systems made for racing only.

Do replace the plugs. I prefer double platinum Champions or double platinum or Iridium NGK plugs. Use an anti-seize compound on the champions, put NGK's in dry as they have a special anti-seize plating that does not work well with the anti-seize compounds.

The cam position sensor is a capacitive plate under the 1/4 coil that uses the spark characteristics to determine which cylinder is under compression at the time. This is a lost spark system, so the coil fires every time the piston is at the correct timing point, but half the time it is on the exhaust stroke so it doesn't do anything.

The 1/4 coil fires every time the pistons for 1 and 4, which come up together, are near TDC. But one of them will be on the compression stroke and the other will be on the exhaust stroke. The resistance of the spark plug gap will be different for the A/F mix under compression and the other one with burned gasses around the tip. That changes the voltage and duration of the spark for each plug. The computer uses the capacitive plate to determine which one was under compression and that is used to time the fuel injectors and the spark for the next cycle.

If either of the 1/4 plugs, wires or coil is not working or has a significantly different resistance than the other under the same conditions, the cam sensor will not work. You will get the P0300 and P0340/341 codes.

You can clean out the EGR valve yourself, I have done that, but it took a lot of time and work to do it. You may decide that it is just easier to buy a new one, however, do the plugs first as sometimes the missing am position signal can trigger the P0345 code. More often it is triggered because of carbon build up around the valve in the EGR assembly keeping it from closing completely. When you do replace it, spray some carb cleaner down the both holes that the EGR goes to to make sure they are clear. One hole goes to the exhaust, the other goes to the intake.

BTW, my ignition wires were never change and worked like new. I sold the car at 275k. Todays ignition wires can easily last the life of the car unless they get physically damaged. Do use a little silicone dielectric grease around the ends of the wires when you install them on the plugs.

 

Keith,

Thank you so much for the information! Would you say the pressure on the plugs should be about 40? When I put them in? I'll start out with what you suggested and follow up with a post on here about the results- again thank you!

 

The pressure I was talking about is compression of the air and fuel on the compression stroke. During the compression stroke, the fuel and air will ionize as the coil discharges, lowering the resistance of the gap and causing the spark to occur with less voltage, but more current and longer duration.

When the coil fires on the exhaust stroke, there is less pressure around the spark plug tip and no fuel. The exhaust gasses will ionize less so the resistance across the gap is higher producing a higher voltage, shorter duration spark. This is how the computer determines which cylinder was TDC for compression and which was exhaust.

From you comment, it sounds like you are asking for a torque spec when installing the new plugs. There is some controversy about using torque specs vs the old 1/8th or 3/4ths turn past snug. Torque is affected by so many variable besides pressure on the threads that it is not as accurate as many people believe.

But, in an aluminum head I still prefer to install plugs using a torque wrench. I don't remember the specs for the Saturn as I gave away my FSM after selling it, but what ever it is, if there is a range, set the torque wrench at the lowest setting. I once had a plug strip the threads in the head before even reaching the specified torque, and that was on the first plug replacement in the vehicle. (for the Saturn, if I recall correctly, it is 13 -21 ft lbs, but check first)

The general rule of thumb is to make sure the threads are clean enough so that the plug screws in easily and you can feel when the seat has made contact. Then if the plug has a tapered seat and no gasket, you go 1/8th turn more. If the plugs have a gasket, you go 3/4th turn after contact.

This is what I use, but I still have a torque wrench set at the lowest torque spec. If it clicks before reaching the desired turn angle, I stop there. If it is close to the desired turn angle, I leave it, if it was significantly less, I remove the plug and investigate why.

If I reach the turn angle and the torque wrench has not clicked, I stop and don't worry about it. The torque setting was just a backup for me.

BTW, check the package the plug came in to see if the torque angle is other than what is generally used. If it is, use that instead. Most plugs don't come with those instructions anymore, but you may find that information at the website of the plug manufacturer. NGK has very good instructions on their website, at least they did last time I looked, but that is for their plugs only.