car idiling bad.. misfire?

[cam98aro]

hey guys, just used my car, it snowed about 2" here last night, and my car was a bit stuck in the snow, and i stalled it out trying to leave, no big deal, started it back up and went on my way to the gas station

after i started it back up i noticed my idle was a bit low, but when i finally got home i noticed the car was shaking a bit, sounds like i put a pretty nasty cam in it, and i smelled rotten eggs

im at a friends house, and i have no tools and no way to fix it, but do you guys think it maybe a misfire? the SES light is not on at all.

im thinking its either a misfire, or a clogged cat, my exhaust has been rattling for over a year now, not sure if it is the cat or not, but its the stock cat at 140,000 miles

what do you guys think about me driving it home about 30 miles? i dont want it to die on me

[techsan23]

Re: car idiling bad.. misfire?

Given the smell, I would bet on the cat being clogged. If it were me, and I could get it up to highway speed without any problem I would drive home. When you get there, peek under the car and see if the cat is glowing red.

[cam98aro]

Re: car idiling bad.. misfire?

Given the smell, I would bet on the cat being clogged. If it were me, and I could get it up to highway speed without any problem I would drive home. When you get there, peek under the car and see if the cat is glowing red.

i just started it and let it run for a bit and i did not smell any egg smell.

i looked under the hood and the manifolds were not glowing or anything.

i do know that a misfire can cause an egg smell, a friends mustang had a misfire when water got into the plugs, and it smelled really bad.. but he had 2 or 3 cylinders misfiring.

thats why i was confused as to if it was a clogged cat or a cylinder down, when i was driving, it ran fine, i just noticed that the idle was loping pretty badly

after about 1500 rpm the engine gets smooth, and i would never know if there was a misfire/problem or not

if i rev it up, it will go down to idle and it will seem to idle good for less than 1/2 second, then the idle will get rough then it will start to lope.. this is all within a ~1.5 second timeframe

thanks though, i will def. look next time i start it

[Mighty Thor]

Re: car idiling bad.. misfire?

I'll say that it was running very rich and your cat may have been affected by it. Cold weather can sometimes do that.

Here in Calif. is insane. It was 86* last week with low of 68*. Then all of a sudden it went down to 67* with a low of 47*. I felt my car shaking quite a bit from these 2 extremes.

[nimrod.sixty9]

Re: car idiling bad.. misfire?

after about 1500 rpm the engine gets smooth, and i would never know if there was a misfire/problem or not

Sounds like my ride when my CAT clogged.

After driving it, at night, look directly at the CAT (not manifolds) to see if its glowing red...

[cam98aro]

Re: car idiling bad.. misfire?

I'll say that it was running very rich and your cat may have been affected by it. Cold weather can sometimes do that.

Here in Calif. is insane. It was 86* last week with low of 68*. Then all of a sudden it went down to 67* with a low of 47*. I felt my car shaking quite a bit from these 2 extremes.

thanks, i live in PA, and its been pretty cold lately, it has been below freezing outside for the passed week or so, except for yesterday where it got to about 38F

Sounds like my ride when my CAT clogged.

After driving it, at night, look directly at the CAT (not manifolds) to see if its glowing red...

thanks, its probably my cat that i hear vibrating then, i did notice more vibration out of it yesterday, but i thought it could have been because the engine was running rough

for the passed year or so, whenever i am at about 2000rpm i can hear rattling, and if i am engine braking it does it, same with them the rpms go down when i shift

[nimrod.sixty9]

Re: car idiling bad.. misfire?

I wouldnt go by rattleing. At least not only. Remember (if your stock) the pipe has a pipe within a pipe. And this may be the rattle you hear. I have yet to have a 3.8 not do what you describe. Even after getting my CAT changed I still had the noise.

I cant remember how mine did when engine braking. I just know when I took off it was like I didnt give it enough gas to push it, like letting off the clutch too early. And after slowly getting up to speed it started to smooth out. When I looked under the car the CAT glowing like an eye on a stove.

[cam98aro]

Re: car idiling bad.. misfire?

I wouldnt go by rattleing. At least not only. Remember (if your stock) the pipe has a pipe within a pipe. And this may be the rattle you hear. I have yet to have a 3.8 not do what you describe. Even after getting my CAT changed I still had the noise.

I cant remember how mine did when engine braking. I just know when I took off it was like I didnt give it enough gas to push it, like letting off the clutch too early. And after slowly getting up to speed it started to smooth out. When I looked under the car the CAT glowing like an eye on a stove.

hm, well how long do you think i can drive like this?

i need to make a trip to the gas station thats about a mile away, and i need to go home, which is probably around 20 miles or so

[nimrod.sixty9]

Re: car idiling bad.. misfire?

I dont know exactly what else it could hurt. But I did drive mine about 100 miles after it went out because I was at a gas station in the middle of nowhere (about half way through my trip). Just a pita to accel. After that was replaced I was good to go with no other issues.

Now Im no expert in this and this is not me telling you to drive it LOL, its just my experience.

[cam98aro]

Re: car idiling bad.. misfire?

I dont know exactly what else it could hurt. But I did drive mine about 100 miles after it went out because I was at a gas station in the middle of nowhere (about half way through my trip). Just a pita to accel. After that was replaced I was good to go with no other issues.

Now Im no expert in this and this is not me telling you to drive it LOL, its just my experience.

ha, well thanks, im not really worried about breaking my car as i am about driving and having it totally clog up on me and stall

when i was letting it idle though there was a decent amount of pressure coming out of my exhaust

[nimrod.sixty9]

Re: car idiling bad.. misfire?

Im also finding out now that you could just have bad gas. Even so, it may have already killed the CAT. I would start with good gas and a fuel filter, and maybe an additive that you trust before changing the CAT. Especially if shade tree machanic tests says the CAT passes.

[cam98aro]

Re: car idiling bad.. misfire?

Im also finding out now that you could just have bad gas. Even so, it may have already killed the CAT. I would start with good gas and a fuel filter, and maybe an additive that you trust before changing the CAT. Especially if shade tree machanic tests says the CAT passes.

it could be, but i have had the same tank for over a week now with no problems until yesterday, although i did think about the fuel filter/fuel pump as i have seen that it can cause a lopy idle, but im a bit weary about that, if anything i would think that would cause a very rough idle, while mine is lopey, rpms are surging up and down by about 200rpm and it sounds like the engine is cammed

actually, i wonder if it could even be a vacuum leak

edit** now that im thinking about it, i think it could possibly be a vacuum leak, or a problem with one of the TB sensors, or EGR

the idle does more surging up and down than it is actually rough

[nimrod.sixty9]

Re: car idiling bad.. misfire?

Good observation, but if thats the case then you should be throwing codes. And as for having the gas for awhile... remember snow, theres always that small chance. Id get to AZ and check codes (codes could be stored but not showing SES) and fuel pressure; just to safely rule that out. Also test your TPS and IAC. I might be leaning more towards TPS because that thing can send your a/f everywhere.

[cam98aro]

Re: car idiling bad.. misfire?

Good observation, but if thats the case then you should be throwing codes. And as for having the gas for awhile... remember snow, theres always that small chance. Id get to AZ and check codes (codes could be stored but not showing SES) and fuel pressure; just to safely rule that out. Also test your TPS and IAC. I might be leaning more towards TPS because that thing can send your a/f everywhere.

yeah, i have a scanner, just not here with me, which sucks.

a bit later today im going to start it and unplug the sensors and see what happens

[cam98aro]

Re: car idiling bad.. misfire?

i have an update

it was too cold today to be playing with the car, but it was bugging me, so i went back out and started the car up and let it idle for a while.. still the same problem, but it seemed a lot less, and it barely did it while the rpms were higher while it was still warming up, once they went down, was still surging, but a lot less.

looked under the car, and the cat was not glowing or anything

shut the car off, and went inside for a while, the problem still bugging me, i went back out, and when i went to start it, i held the key for about 3 sec. and it did not start (my car ALWAYS starts the second i hit the key) turned the key off, then hit it again, and it started up like normal.

anyways, i went on a little drive, and when i shifted my rpms went up when the clutch was pressed in (it went to about 3500 rpm).. now my car does that every once in a while, and i dont know if it is because i wasnt paying attention and i didnt remove my foot from the gas all of the way or what, but i pulled into the gas station, and got some stuff, and when i pulled out of the gas station i noticed that the idle was 100% normal again.

so i am assuming it may have been the TPS that was messing up, hopefully the problem doesnt come back, but if it does, im going to replace it


and a bit of offtopic, but when i was at the gas station, i pulled in next to a state trooper, who was inside with his engine running... real smart