For the last couple months I keep getting intermittent CELs coming on and each time I've had it checked it's been the evap leak for the gas cap. About a month ago I took my car in for an oil change and to get the CEL checked out since I couldn't get it turned off and Autozone couldn't pull a code for it. They told me it was "the gas cap and a bunch of other codes caused from the gas cap." They didn't tell me what they were when I asked. I was told they were all triggered by a defective gas cap (I'm now on my 5th gas cap so I doubt I really have that many defective ones). Since my oil change I have driven about 400 miles on the car (I've got a little over 56K on it now). I've been having progressive problems ever since then when before my car was driving and sounding perfectly fine until the oil change and gas cap change. After I'd driven it about 100 miles one day I noticed my car was starting to have a weird ticking sound coming under the hood at idle. At this time the car was still driving fine with no power loss or stalling or anything and idle still felt completely smooth. I looked all over and couldn't find anything obviously loose or disconnected.


I went to drive my car a few days later and it was still running fine but still had that ticking sound at idle. Right at the end of my 20 mile trip I noticed my car felt like it was stuttering when I was driving at a steady speed and also hesitating a little on acceleration, but no obvious power loss. I thought it was possibly due to high 90-degree weather. When I got to where I was going and parked I noticed that there was no longer any ticking at idle. Before the ticking was come from somewhere on the driver's side in the engine bay in the upper half of it but I couldn't localize it any further.

Fast forward to Saturday. I was driving and after about 30 minutes of driving my car started doing that rough sounding idle and I was noticing that now my RPMs sitting at idle for more than a few seconds drop down to around the 750 mark when normally it's been right about the 1000 mark or just a tad under up until that moment. I also noticed that on this fresh tank of gas it hit the 3/4 full mark at 50 miles when it's normally about 65. I was really close to work so I decided I'd at least continue to where I was going. While sitting at the first stoplight at the top of the offramp the car started shaking violently and stalled. It restarted right away, not even a slow sluggish turnover like I've been having off and on for what seems like forever with no relation to temperature, and continued driving but was running a little rough. No CEL, overheating, or anything else. No lights on. Since I had just stalled I didn't want to shut the car off right away so I drove it around for about 10 more minutes before pulling into the parking lot. I noticed the car was starting to smell burnt right about that time coming from the front of the car. Idle was still a bit rough. I looked under the hood and saw that there was a big greasy oil stain coming up through the vents in my engine cover on the driver's side and running back up toward the firewall. Underneath the cover was corresponding oily stain on the engine parts. I saw no leaks or any evidence of where it could be coming from, just the stains there randomly. The only possible place it looked like it might be coming from was that the oil cap had wetter looking oil around it, but when I checked the cap it was on tight. Everything else looked fine. Still no CEL or any other lights.

I had some errands to do today before work so I thought I'd try out the car and see how it was working. It started up extremely slow and sluggish and just barely turned over and then sputtered briefly but kept running. Idle went to it's usual 1500-2000 level on startup. No ticking sound. Engine sounded okay. Heard a few light popping sounds from the exhaust like burning off fuel but no smoke as would normally be expected. I drove around for about 10 minutes (taking a long route to the store) and noticed that it was idling really rough again after a little bit but was driving fine and accelerating fine. No lights coming on. I did notice a slight rattling sound around 4000 RPMs in 1st gear that sounds like a vacuum cleaner sucking up sand, kind of a crackling. I didn't hear it in 2nd or 3rd gear at that range (wasn't anywhere to need higher gears). It was still doing a bit of a stuttering feeling while driving though after it warmed up and I heard a kind of a light clunk or pop from the rear of the car twice when I was stopped at a light. Still didn't see any smoke or anything or smell any strong smells. Pulled into the parking lot and the car sounded okay but the idle was still shaky. It didn't stall out or anything while I checked under the hood. No new oily stains or odd sounds. Thinks looked okay. After being in the store for about 15 minutes I went to start up the car to leave. It made that same slow, pathetic slow turnover and sputter again and that exhaust popping sound. Still idling rough. No lights on. I have to leave in a little bit and hope it starts. If not I'll have to walk, but at least it's close enough. Just planning to leave a bit earlier just in case.

I forgot to mention that after the rough idle and stalling and finding the oily stains, when I checked the oil level on it cold after that, the oil level was definitely above the full line on the dipstick even considering the apparent leaking the other day. Is it possible that overfilling the oil could have caused these problems??? I was also thinking a problem with the cat going considering the strange feeling while driving and accelerating. However, I passed DEQ about 1500 miles ago and wouldn't a cat going out have caused me to fail? My only other thought has been something with the fuel pump or a problem with the fuel injector because my car acted like this when I had a blocked one two years ago due to something getting in the fuel line, although my car had a flashing CEL at that time and completely died.

I'm also thinking I need to replace my plugs and coils again even though they are only about 6000 miles old. I was having some strange starting and no power issues at that time and had my car all checked out including a compression test and was told things tested out fine, probably just needed new plugs. So I replaced the plugs and coils and the car was running fine with no power loss, just intermittent slow/hard starts with no definite correlation to the weather, although definitely frequent while wet and/or raining. In any event, I am taking my car in on Monday to get it checked out again and will also be replacing my plugs, coils, and wires at that time (might just get the 60K mile service done then even though it's a little early). I'm hoping there are no major issues at this time.

Also, would an engine fail as soon as 5K-6K miles later after having a good compression test?

My results at that time @268:
f: 7.9, 7.8, 8.3
r. 7.8, 7.7, 8.1

 

Overfilling your oil can cause this issue IF you have one of the hoses running from your oil fill to your air intake. Basically check the hose that comes out the front of the oil cap and see if it goes to the drivers side...if it does you need to clean your intake, MAF sensor and throttle body. If it goes the other way my guess would be plugs, coils or loose plug wire.

 

I'll have to check that on my break since I'm at work now. Car still pathetic but running and idle crappy. Since it wasn't a long trip it wasn't dying on me or stuttering. All my hoses, wires, and connections are tight. After draining a quart of oil out it's just past the full mark on the dipstick now. I'm thinking my plugs/coils are bad already considering the starting problems now.

 

wow BunnyGirl is still here?

i haven't seen her post in... ages.

 

LOL! I've been busy.

Now since my car is still running crappy, barely cranks and turns over to start, rough idle, and popping exhaust sound, could that all be caused by overfilling the oil when they changed it? I can tell the plugs and coils need replacing considering the barely there startup and likely drained battery as well. The car runs like it's been flooded but there is no smoke or anything as would be expected, just falling gas mileage on this tank of gas now. I guess the question is what else is likely to have happened to my car from overheating and being overfilled with oil?

 

coils aren't going to drain the battery and I wouldn't call it a rough crank when they do start to really go and they won't be going at 5K miles...more like 30-50K. However, oil on the MAF sensor and a gummed up throttle body would give you a horrid start and idle.

 

Take out your cat and inspect for blockage or breakage, I think it is the cat problem more then coil.
Like Devil said the MAF need cleaning too once in a while.

 

I got the codes from the CEL I had last time when I took it in and was told it was my gas cap that triggered the CEL. The codes I got were P0454 and P0420. I was told the first one caused the second one and that fixing the first one would take care of everything, which led to the swapping of gas cap again and turning off the codes, then the relatively rapid decline of my car's functioning. All the previous CELs before this one had been the P0454 code as well when I had them checked at Autozone without taking my car to the dealership, which would seem to come and go at random. I'm guessing that when I redid the gas cap the last time and the light didn't turn off it was because the P0420 was still there? If that's the case, and considering how my car is behaving right now, shouldn't I be triggering a CEL again??

If I searched correctly, P0454 is the gas cap and P0420 is the cat, right?

 

easy way to test your cats, put your hand over the exhaust. if you feel the exhaust pulsing, then your cats are fine, if you feel constant flow over the exhaust then there is back pressure in the system and you need to check your cats.

 

Burnt out wire and plug. Everything else looked fine including inside the cat. It's a little weird to me that it could go bad already after 6000 miles. Maybe I just got a bad part when I replaced them last?