problem time. random mifire.

[blueolds01]

ok so today i changed the t-stat to a 180* in class. well when got my car back together it idled like crap. you can rev it up and its fine, but at idle is really rough. so the service engine light came on and i had it read and i was told it was a random misfire. my teacher told me that 1 of the spark plugs were bad before i got it read, but i see no problems with plugs or wires. both are fairly new, maybe 2 months old. my car was running fine when i took it in. im open to ideas, let me know.

[rustyballs_69]

Did you unplug anything?

[blueolds01]

yea, a few sensors and 3 spark plug wires. i double checked them all though.

[rustyballs_69]

Its possible that you may have bumped something. I can't really think of anything right now. Is the misfires on the cylinders that you had the plug wires off of?

[blueolds01]

the guy at autozone didnt say, he just said 'random misfires' which i found quite strange. i was gonna go up tomarrow morning to another autozone and have them read it again. the one i was at tonight had some kid working there that looked like he didnt know what he was doing.

[rustyballs_69]

Yeah take it to the other autozone. He could have told you what cylinders were misfiring. I would check the plug wires also, sometimes when you pull them off they get fucked up. I would also look at the spark plugs, if the porcelain on the plugs are cracked they are fucked. Just somethings to look at.

[blueolds01]

when you say effed up wires, does that mean they need to be replaced?

[rustyballs_69]

Yeah, The boot that slips over the plug has a little metal thing in there that holds onto the plug, sometimes when they are pulled off it will mess them up. Were the wires hard to pull off?

[blueolds01]

yes they were. well ill have the code read again tomarrow and go from there. thanks for your help, ill post up tomarrow.

[rustyballs_69]

Its probably your plug wires then.

[cavaliers60]

x2 on the plug wires... I actually ripped one of them off the metal piece that holds the wires and plugs onto the spark plug.. those things snap on the plugs like no other! Just to be on the safe side, I'd just double check those spark plugs as well...

[Cliff8928]

Yeah take it to the other autozone. He could have told you what cylinders were misfiring.

Not necessarily, It could just be a P0300 which is a random cylinder misfire.

[rustyballs_69]

Not necessarily, It could just be a P0300 which is a random cylinder misfire.

Your right cliff. I looked through the codes in my book lastnight but didn't see it. I found it in there today though.

[AsianAlero]

make sure your wires are crossing right, could be emi or something.

[Gr1m]

hehe make sure you have the right wire going to the right plug

[blueolds01]

well my teacher said that its prob the wire too. so im gonna just go out to summit this weekend and get a new set. thanks for your help. if its still doing it this weekend ill let yall know.

[misslindseysue]

Be careful driving with misfire - that could really damage your cat and screw up a lot of other stuff. If your SES light comes on and is blinking, STOP DRIVING!

[blueolds01]

okay. i went to summit picked up some new wires...35 bucks. and its still doing it. any other ideas?

[TheEdgeofSanity]

Be careful driving with misfire - that could really damage your cat and screw up a lot of other stuff. If your SES light comes on and is blinking, STOP DRIVING!

really? i have a screwed up plug wire and my car's been doing that alot with the blinking SES light because i have a mismatched plug wire that pops off sometimes. i didn't know that it could damage anything though.....on man another $30 down the drain for plug wires...

[alerored04]

did you have the tb off? a tear in the tb gasket or any other leak after the maf will cause the symptoms you describe.

[misslindseysue]

A blinking MIL (er, SES light) means, by law, catalyst damaging misfire. Fuel goes through the engine, but doesn't burn because of the misfire. Unburned fuel blows through, hits the catalyst, and explodes, basically. Super high temps will melt or break a cat brick. Cats aren't cheap, and you'll have a hard time finding anyone to replace exhaust without a cat, since it's illegal in most places and all.

[CharleyO99Alero]

***

I had this random misfire a while back but only at start-up and occasionally at idle. I replaced the coil packs (2.4) and it ran correctly for about one day. So, I thought maybe it's an injector problem. For the next 6 tanks of gas, I added injector cleaner. It would run ok for a few days and then back to missing occasionally. The final solution for me was a bottle of Marvel Mystery Oil in the gas tank at the 7th fill-up. I can't say this is your problem but that cured mine. By the way, the random misfire was on the #3 cylinder so I suspect that injector was sticking at idle.

I hope this helps you or someone else with a similar problem.


***

[TheEdgeofSanity]

A blinking MIL (er, SES light) means, by law, catalyst damaging misfire. Fuel goes through the engine, but doesn't burn because of the misfire. Unburned fuel blows through, hits the catalyst, and explodes, basically. Super high temps will melt or break a cat brick. Cats aren't cheap, and you'll have a hard time finding anyone to replace exhaust without a cat, since it's illegal in most places and all.

oh man, well, how do you know if your cat is messed up? i have plug wires ordered but in the mean time, the broken one occasionally comes off and causes the ses light to go on.. i stop as soon as i can and fix the problem tho, so that should keep the catalytic converter from getting too hot, rite?

[billytheman1188]

oh man, well, how do you know if your cat is messed up? i have plug wires ordered but in the mean time, the broken one occasionally comes off and causes the ses light to go on.. i stop as soon as i can and fix the problem tho, so that should keep the catalytic converter from getting too hot, rite?

LOL, dude, i would have went to the closest auto parts store and bought new plug wires. your crazy dude, that shit can mess up your car.

[TheEdgeofSanity]

the night that it started acting up, i went to Murray's Auto Parts and i want Delco plug wires. they'rew ordered and supposed to be here tomorrow... i still need to go places so i gotta drive the alero...but seriously, i pull over as soon as it messes up and put the wire back on so that wouldn't let the cat get too hot, would it?

[misslindseysue]

I've seen a car eat a catalyst within a couple minutes. It's hard to say without thermocouples and emissions data what your cat looks like now. Just be careful - it's not likely that a minute of misfire will kill it, but eventually it's definately at risk.

[TheEdgeofSanity]

k, thanks misslindseysue for the info... i'm going to change those wires out as soon as i get them

[blueolds01]

did you have the tb off? a tear in the tb gasket or any other leak after the maf will cause the symptoms you describe.

we didnt take off the tb but maybe somthing got bumped. im at school right now were going to check it out and see if we can fix it. ill check all the hoses and make sure there were there suposed to be. thanks for the help.

[blueolds01]

so at school we came to the conclusion it was a vacum leak. i am going to try to replace the upper intake many gasket and see what that does for me.

[blueolds01]

replaced it! it works! yay!

[rustyballs_69]

Thats good news. Glad to hear its fixed.

[Gr1m]

vacuum leaks ftl

[alerored04]

/\ x2. most of the time they are a total pita to track down too.

[blueolds01]

my dad told me i couldnt do it on my own. i told him i'd do it. i fixed it and proved him wrong which makes me extremly proud of myself.

here i come lower intake manifold gasket!

[AsianAlero]

Are your wires crossed correctly? cuz if not it could be interference. EMI