i have a similar problem, the car just stopped firing cyl 3&6, changed the coil, nothing, noticed the cat gets cherry red when ran for about 10 min(if that) that tells me(from my knowledge) that either the fuel from two malfunctioning cyl is igniting downpipe(in cat) or i have a clogged cat, i believe the donut is in need of replacement. if i unplug either #3 or 6 wires from coil, there is no spark jump whatsoever, just dead. checked all the fuses, good. new wires, new plugs, same old problem. i can hear the iac hissing but i believe that is due to lack of fire, compensation. its a 98 chevy lumina ltz, ilove the car, hate the problem....... im stumped/ process of elimination can be an expensive choice but i dont know where to go from here. sum it up would a cat cause this?

 

that is exactly what my car does too..i can hear my intake sucking in more air, especially when i first start the car.

hey defiled, does your car run really rough sometimes when you cold start it? mine does, to the point where it actually kills. but it will start right up a few moments after no problem..i think it is having problem breathing and that is why it is hissing, which makes me think it is a clogged cat..i haven't checked to see if my cat gets red after running, but i will check tomorrow night and see. i've beat on my cat and i can hear stuff moving around in there..should i hear anything when i beat on it moving, or is the inside of a cat stationary? i think it is clogged...

BUT, why is one of my cylinders misfiring!! injector?

still trying to figure this out, i am getting HORRIBLE gas milage!!! help me! lol


Rob

 

i am thinking the misfire may be from too much fuel and not enough oxygen, but why would it only be on ONE cylinder?! wouldn't that cause multiple misfire?

 

if your cat is clogged your going to get multiple misfires on multiple cylinders pertty randomly, my car runs rough from start to kill, i replaced the ignition coil, not it, im going to test the ignition coil module in a second, ill be back to you with the results, im going to hook a test light to where the coil connects to the module and see if i have fire there, if not, ill test the pink wire(runs to the pcm) if no fire there than ill test the camshaft position sensor, then the crank p s, to my knowledge these are the only items that are going to be causing my car to do this, the hissing you here is more than likely you idle air controler staying open to keep your engine running since there is such a lack of fire due to 1 (2 in my case) lost cyl, the fuel runs down the manifold and ignites in the cat,which causes it to cherry) if you have been running your car like this, (which i do not recommend) than more than likely if your cat wasnt clogged, it is now due to extreme heat, which also causes carbon build up on o2 sensor and more than likely that needs to be replaced,...... so what im telling you is i wouldn't focus so much on the cat being the problem as an ignition or electrical(pretty much same ****) problem, ...ill get back to you with my results, brb

ps to clear the codes once you fix this(hopefully soon) yu need to disconnect wither the neg battery cable, the main fuse or the cable running to the fuse deck, and you need to do this for at least 30 sec i believe, not so much 3 hrs.

 

and your cat has a honeycomb type baffle inside, heat durrable but not impact durrable,

http://www.aa1car.com/library/catconverter.gif

this will help.....
i wouldnt suggest hitting it, lol
ijector would cause carbon deposits which if you pull the spark plug can be determined easily.....

http://www.aa1car.com/library/reading_spark_plugs.jpg

that should also help

 

ALRIGHT, i had suspected the control module to be the cause, wasn't sure, so i took it(just the module, w/o the coils attached) up to auto zone and had them test it, FAIL! just for good measure i had him hook up a new one to the machine, passed, then hooked my old one back up, fail again. got the new one(127$) installed it, and hot damn!, lol it runs better than before,.... have you tried this on your car yet? if not i would highly recommend taking it down and getting the ignition control module tested, i hope this helps you with your car trouble. let me know!!!!

 

if you were getting too much fuel that would rule out your injector and i would look into spark plug-wire-coil-ect, the only reason it may seem less sluggish at higher rpms is because faster repetition becomes unnoticable once the rate is increased......

 

Just out of curiosity, have you guys tried cleaning the MAF sensor? When I first bought my Monty I was having similar problems and once I cleaned the MAF sensor they went away. Just my $.02!

 

so you're still not sure if it is an injector issue.... why don't you (carefully) swap another injector from a different cylinder to cylinder #2 and see if the code changes with the cylinder. that would pinpoint a problematic injector.

 

my problem is fixed, it was the control module, next step i want to take a supercharger off another 3800 series 2 engine(gtp) and put it on the lumina. lol is that a dumb idea?