Annoying misfires.....

flypa38 · 05-03-2005, 06:09 AM

My venerable 93 SC2 has an annoying miss with constant rpm's between 2000/3000 rpm's. It's the worst in reverse and starting out up hill. I really have to rev it up and ride the clutch. When I push the clutch back in after backing out of a parking spot, it almost stalls too. Usually accompanied by a "running rich" smell. That sticky gas pedal that others have described doesn't help either!!
So here's what I've tried:
Fuel injector cleaner
New plugs and wires
New TPS
Unplugged coolant temp sensor (ran worse)
Tried using plug anti-foulers in case the leaky valve cover gasket was coating the plugs with oil.
The only error code I got was malfunctioning gear selector switch (I think that's what they called it)
Nothing has changed any of her bad habits.
Any ideas so i don't have to keep throwing $$$ into parts that aren't the culprit???
245,000 miles and the only other problem is the passenger door hasn't opened in three years!!! Can't complain!!!
Johnny

Satyllac · 05-03-2005, 08:03 AM

The only time I had misfire issues with my SC2 was when a plug wire wasn't properly seated on the coil pack terminal. I'd recommend re-seating them and using a touch of that silicone grease to keep the resistance to a minimum.

flypa38 · 05-03-2005, 06:37 PM

That was the very first thing I checked.....fixing vacuum lines today! I'll let y'all know if it helps!

**jonnyrocket92** · 05-06-2005, 04:16 AM

sounds like a vacume leak, also pull the coolent sensor out and check it to see if it, might be cracked " if it's plastic" also check the connector, in the inside to see for corrosion.

moparnum5 · 05-07-2005, 02:58 AM

what plugs did you use? I here the bosch platnum can cause missfires with this engine

SJRocker · 05-07-2005, 04:50 AM

Here's a list of things you may or may have NOT tried.
1. Map Sensor.
2. Oxygen Sensor.
3. Fuel Pump and/or filter.
4. MAFS (Mass Air-Flow Sensor.)
5. CLEAN THROTTLE BODY.
6. Check ALL ELECTRICAL CONNECTIONS. If you have a short ANYWHERE, it could misfire and cause these problems. This sort of thing is better diagnosed by a service shop, and can be moderately cheap to fix.

Any and/or all of these can cause and/or contribute to that problem.
It is best to have all parts of the SAME system be changed at once, than to have a good one be blown by an older bad part.

Later.

SJRocker · 05-07-2005, 04:56 AM

Quote:

Originally Posted by moparnum5

what plugs did you use? I here the bosch platnum can cause missfires with this engine

Ok, LET ME CLEAR THIS UP, AS I RECCOMMEND THESE PLUGS.
Bosch Platinum brand spark plugs are designed to create a cleaner, more efficient spark with a sealed platinum tip, so you don't have a big problem with blow-by. If anyone takes the time to gap the plugs to the right specs, which I can't remember off the top of my head, then you wouldn't have a mis-fire. Also, the best way to use Bosch Platinum Plugs is to use the Bosch Wires, or 8mm performance or higher wires. If by chance the tips can be screwed on or off on the top of your spark plug where it connects to the boot, that could cause a miss, just tighten it with a pair of pliers.
The BEST plugs to use for a N/A engine are the BOSCH platinum +4. The best plugs to use for a turbo, NGK, or DESNO IRIDIUMS.

flypa38 · 05-09-2005, 05:04 AM

Today I cleaned the TB......gas pedal doesn't stick anymore and it took about an hour to get it started again, but she's runnin' the same.....slightly better I guess. I am running Bosch platinums which I gapped individually. I flexed the diaphram in the EGR and it was sticky at first, but didn't change how it's running. With the engine running, flexing the diaphram did cause the engine to bog down, so I'm guessing that the EGR is working properly. I do have some cracked vacuum lines which I repaired before by putting a length of surgical tubing over the crack. I replaced those, but I think the vacuum is fine. I also ran some more fuel injector cleaner through....no change. I replaced the MAP sensor (no change), disconnected the mass airflow sensor(wouldn't start), and cleaned and inspected the PCV valve.....what's left??? Could a leaky valve cover gasket let enough oil onto the plugs to misfire???? I just hope this isn't due to poor compression or something. Just turned over 245,000 today, but she's been well cared for.....
Any other ideas???
Johnny

SJRocker · 05-09-2005, 02:59 PM

Ok, so you did all that. Let's think here for a second. You replaced the Map Sensor, did all this other ****. TAKE OFF THE EGR VALVE, AND JUST COVER THAT **** UP. The EGR valve is NOT required to run your vehicle, it just reburns unused gas. Take it off, and put a steel plate over top in it's place, or better yet, ASK A Mechanic if this can be done. I have done it on a 84 Camaro, and a 93 S10. It just made them run smoother. Check with a mechanic and see if Saturns can do it, because I haven't done it yet. Also, check your O2 Sensor. That could make it bog too. (Damn, they put so many sensors on cars today, it's nearly impossible to check which one it is, so here's a small list of the others that could do it.)
1. Crankshaft Position Sensor.
2. Camshaft Position Sensor.
3. Knock Sensor.
4. O2 Sensor.
5. Bad Battery Cables, CHECK ALL ELECTRICAL CONNECTION THROUGH IGNITION. CHEAPEST FIX, IF THAT IS THE PROBLEM.

kathysc216 · 05-10-2005, 01:24 AM

i was having the same problems with my car i replaced the and wires and the misfireing problem went away and i was also getting the gas smell when i start the car but that went away for the most part. i hear that the stock plugs are the best ones to go with i had some somewhat expensive ones before and i started having problems