Ok guys, hopefully i get a response this time. I tried searching and couldn't find a thing about this problem. I own a 2000 Cavalier 5 spd with the 2200 motor in it. Exhaust is stock and the ONLY thing i have on the motor is a Intake but it was doing this way before that went on. If i am sitting still, in neutral, and I hit and hold the gas, the rpm's go anywhere from say 1500 to 1300 to 1700 and you can hear it in the exhaust when it happens, sorta like a popping. Also the car sorta vibrates as well. Also I have no idiot lights showing up on the dash when this happens or ever. If anybody has any advice please let me know. The car has 54,000 on it and the exhaust hasn't been replace by me since i bought the car at 31,000 which was a yr and a half ago.
How does it drive? Do you get any sags or hesitation during acceleration,? What if you "lug" the engine - do you get any of the "popping" sound then?
If it was consistant misfire, your check engine light should start flashing.
I have a 2002 with the same engine/tranny combo, and I have never experienced that yet myself. My main complaint with mine is the amount of backlash in the drivetrain, which makes it very hard to creep at low speeds without the car starting to buck. It's done this since new, and really hasn't changed. My brother's Ecotec however exhibits none of this, so I expect it's got something to do with a combination of this engine's motor mount design. I think that maybe they just softened up the mounts to help reduce vibration.
The car really shouldn't need plugs yet, but the wires could be aging a bit now. Also make sure that none of the wires are sitting too close to any metal parts which could wear into them. I doubt that they're too bad yet, or you'd likely have much worse problems.
If acceleration is poor, you may want to change the fuel filter if it hasn't been done yet. Proper fuel pressure is very important to allow the injection system to work properly.
http://registry.gmenthusiast.com/images/2002sunfiresl/Modified%20sunfire2.jpg
Hmm, well the fuel hasn't been changed yet, but acceleration actually doesn't seem to be a problem, it seems to get up to speed just fine. Would poor wires cause it to have irradic RPM's when holding the pedal steady? Could it be exhaust or would the computer catch that and throw a code? Also the other day, I heard a loud pop sound come from the car while driving, its the ONLY time it ever happened and hasn't happened since. And this happens even if im driving and i am going a steady speed, i just came back from dropping my g/f off and it was doing it at 2500. I do still have a warranty on the car, its the extended one you can buy, do you think i should bring it in to the dealer and have them check it out, or will they tell me nothings wrong because theres no light showing up? Sorry for all of the questions, im taking a trip down to Florida in April and wanna make sure ill have smooth sailing during the trip. My exhaust is all completely stock and i haven't touch it since i bought the car. Well thank you for the help. Any more advice please please let me know.
Maybe idle air contol (IAC), or throttle position sensor (TPS), but those should throw a code. The popping noise is usually due to unexploded fuel passing into the exhaust, getting heated and, well ther ya go.
What causes it is the question that I cannot answer.
Maybe an O2 sensor is out to lunch, but you should have the ECM scanned, that should isolate the issue.
Worst case, it could be in the cylinder head, an exhaust valve or 2 might not be seating properly.
Wires and plugs, along with coil packs could also be an issue as stated before.
There are many causes to this, just a matter of narrowing it down.
Start cheap, (ie, plugs and wires).
You may want to take the car to a GM dealer for a proper diagnosis of the problem. They have the tools available to properly monitor each sensor in real time, and can sometimes spot something that isn't quite right, even though the computer doesn't realize it. If a sensor is putting out a reading which is incorrect, the computer may attempt to compensate for that, causing undesireable results.
The reason I say to use a dealer is that they should be the most familiar with all of the figures and readings that the sensors are sending, where to someone who works on all different kinds of vehicles may not recognize something as being out of place. I did a co-op program 12 years ago at a GM dealer doing electronic and driveablity diagnostics, and I know it took me a while to get used to know what I should or shouldn't be seeing for different applications. They also have tools available which are specifically designed for their own vehicles.
I know that OBD-II is now the standard, but many scan tools will only give you codes which the computer has kept in memory. These only help guide you in knowing where to begin looking - they in no way will always tell you exactly what the problem is. I'm not saying that another garage won't have the ability to do a proper diagnosis, but if you have to pay them for 3 hours to figure out something the dealer could possibly do in 1, which is going to be cheaper?
If the car is running fine otherwise, throwing money at things randomly will do nothing more than help deplete your bank account. You can start by changing the plugs (use a direct replacement if possible), and if you want to check the wires, try opening the hood in a very dark location with the engine running. Have someone open the throttle to simulate the condition you are experiencing, and look to see if there is any arcing occuring near the wires. If there is, just replace the set. If not, you could get your diagnosis done at that time. If there is any question on the condition of the wires though, just change them - they aren't too expensive, and 5 years is a pretty typical lifetime for them. At least if the wire and plugs are new, they won't try to put the blame on those when you get the diagnostic done, and they won't try to sell you a tune-up while you're there.
You can also try a compression check while you're changing the plugs (if you have the equipment - it's not hard or time consuming). That will at least verify that things inside are working as they should. Don't worry too much about the actual reading - just that all cylinders are fairly even.
It could be something as simple as a bad crank sensor missing a beat here or there, a bad spot in your throttle position sensor, a vacuum leak going to the map sensor (or bad map sensor), 02 sensor problems (less likely, but possible), or even a wiring issue (high resistance somewhere, or a corroded connection). It's just too hard to start guessing beyond the basics without a proper diagnosis.
http://registry.gmenthusiast.com/images/2002sunfiresl/Modified%20sunfire2.jpg
See the wires in their now are fine, there isn't really anything wrong with them at all, no wear or anything, i guess my only step is tomorrow i will call and make an appointment, i just hope the dealer doesn't screw me and say there is nothing wrong and i still have to pay for the diagnostic when i personally know there is something wrong. Just out of curiosity, do you guys think that they will try to blame it on the intake? I mean this has been going on for awhile before i bought the intake. I mean the IAT Sensor is brand new as well. Thank you guys soo much for the help though, it atleast gives me a step forward to try to figure out the problem is. I appreciate it.
