Ok so last week after some hard driveing my car started misfiring really bad to the point where i thought i blew the engine but i feel like i can safely rule that out.
Here are the problems im experiencing the car wont idle properly its always fluctuating between 900-750 rpms and as im watching my interceptor it will pick up random misfires cyl#2 seems to be the most common but its happening on all of then. The misfires dont seem to coincide with the idle fluctuation but you can hear the miss's out the exhaust. iv already pulled the plugs and they all appear to be fine. while crusing the car will run much better it doesnt miss nearly as much and runs pretty normally and under wot it is absolutely perfect.
me and my friend whos is a bmw tech started diagnosing or trying to tonight. we were mostly just listening to things to see if we could find differences and while listening to the injectors #2 has a much softer tone to it then 1,3,4 the timeing is the same but its a much softer tick which might possibly mean i have a bad injector but i feel like it would get worse under power not better.
Thursday im gonna clean the MAF and Throttle body and change the plugs and see if that gets me anywhere
also opening the oil cap or pulling the vac line that runs back to the intake will smooth out the idle
im open to any and all opinions so let me know what you think

 

bump
no one even looked at it =(

 

Swap the #2 coil pack with another cylinder to see if the missfire moves. Swap the plug next.

 

hmm yea ill give that a try also but its still picking up misses on all the cyls tho 2 just seems to be most common, but ill def try that and see if it moves

 

any other suggestions guys????

if its an injector problem imthinking at least to test it i could flash my car back to stock and put the stock injectors back in and see if the idle problem goes away i could set it to bleed boost after 10psi so it would at least be safe to drive with the smaller pulley i have on. im kinda grasping at straws but if new plugs and cleaning everything doesnt solve my problem idk what else to do

 

morning bump

 

Swap the coils yet. You need to start eliminating stuff. If you have a bad injector you can unplug the injectors with the car running. If there is a bad injector, when u pull the connector there should be little to no change in the way the car runs.

 

i would do what ^^ has said. my first guess would have been spark plugs or coil pack but a bad injector would do it too

 

hmm alright thanks guys i just swaped over the coils so im gonna see if that makes a difference #2 was the most common misfire so now it should be #1

 

my random misfire (random & mainly #4) was dirty air intake, & bad o2 sensor, now i am just down to a cat inefficiency code.

 

ok well i moved the coil pack and i cant really tell if it made a difference # isnt missing as much as it was but #1 where i moved it to isnt missing as much as #2 was
i also updated the tune on my car and it seemed to reduce the amount of misfires id get while crusing but they it is still missing alot at idle, but its muchh smoother only fluctuating by 70 rpm or so
this is just wierd to me bc i feel like if it where a fuel or ignition problem it would get worse under load not better
and i am noticing my gas milage is way down i went threw just less then 1/2 a tank of gas in less then a day and 110 miles of driveing im gonna get about 230 out of this fill up i usually see 280-300 depending on how i drive
my afr is spot on tho 14.5-15.0 while driving 11.2 at wot and about 14.0-14.3 while idleing

also the car isnt throwing a code but im watching it on my interceptor and i can feel/hear it while driving at low speeds
gonna clean the throttle body and maf sensor on thursday and see what happens

 

how old are your plugs? are they copper or platnum?

check the plugs, maybe changethem, clean the MAF and air filter, and the TB. go from there

 

plugs are about 15k miles old there the step colder ngk bkr7e gapped to .040
im getting new ones on thursday so well see what happens

 

ok so i cleaned the maf a throttle body and my 1st impressions were that it cleared up the issue i did this with about 1/8th a tank of gas left and i drove the car for 2 days and it didnt misfire once in about 55 miles of driving.
i filled up with gas tonight and as soon as i pulled back out on to the road it started misfiring again WTF could this have something to do with the gas tank or fuel filter bc its confusing the hell outta me lol
just to note i only got 90 miles out of my 1st 1/2 tank of gas and then i got 190 out of the 2nd half on my last fill up which i thought was really wierd. im gonna change the plugs on tuesday just bc i have them but i doubt its gonna change anything
any thoughts or opinions are welcome

 

I had a 97 cavalier that had a really bad misfire on cylinder 2 as well. it would sputter at an idle and you could hear the misfire but would smooth out at higher rpms. It ended up being a bad o-ring on the #2 injector. I know they're different cars but take it for what its worth and good luck!

 

appreciate the input ill definitally take a look at that this week

 

Got any friends with a tech 2? You may just need a crankshaft variation relearn. It is supposed to be done every time the ecu is flashed. Because no two engines are the same, it learns small diffences in crankshaft velocity after combustion. This is more critical on 4 cylinder engines. This could be your issue. Dealership might do it for free, but it shouldnt cost more than 100 bucks if they charge you. Takes about 30 seconds with a warm engine.

 

My friend said this could be the issue i guess ill have to look into it
i have reflashed the ecu alot in the past month

 

I've got similar problems going on, did you ever figure out what was going on. I have a ton of mods, K&N intake, Jet MAF, zzp stage 3 kit with the 60's, and same ngk plugs you have. I recently changed the downstream o2 sensor with no change. going to change the upstream.
What is a crankshaft relearn? Can a GM dealership do it, or will they just screw me? I know I have the idle issue due to the K&N intake, and am trying to find a stock air box to put back on to test... don't throw away stock parts guys

 

Try swapping the injectors then clear the codes and see if the code comes back with a different cylinder then just to be extra sure swap the injectors again and clear codes repeat.... Had the same problem on another car and thats what I to trouble shoot it. Returned all four injectors and they flow tested them to find out all four were actually in failing critieria but the one was the worst.

 

try getting a new, emissions purge valve thingy....sorry can't remember the name...
the reason i say this is because after reading tons of threads dealing with gas...that one always comes up as causing some pretty crazy problems, everywhere from car wont start after filling up, to car surges after filling up....and things only seem to get better the lower you get on the tank of gas...i dunno do a search ... for evap purge solenoid i think it's called.
At this point it sounds like it's worth a shot for ya.

 

I would say get someone with HP Tuners to link up to your car and see if he can see something going on there. my buddies sti is doing the same thing right now so when he figures out whats going on on his ill repost what he did!!