car randomly starts misfiring

[cheapscheisst]

alright, so i've got an s13 blacktop in an s14 chassis, been running this setup for almost a year now. about two weeks ago, i went to start the car (i use it as a daily) and it misfires badly (idle around 400, barely staying alive, etc.). I take it around the block to see if i can't figure out the problem. Sometimes the car will run fine for a second or two, then begin to misfire. also, the misfires aren't just every so often, but more frequent than the actual firing pistons (sound like a car with a huge cam at idle). so i shut the car off, come back to it an hour later, start it up, and it runs fine, no problems. drives great for a few more days, then i go to start it after work and same issue. the fact that it is random leads me to believe it's a faulty wire, but i'm really not sure. which components could be causing this? i'm pretty sure the coilpacks are fine. could it be the ignitor? also there's a chance that my CAS is bad (when being timed, the engine will randomly fluctuate in timing without moving the CAS), could that be causing this issue? any help would be greatly appreciated.

[Red Devil]

have you pulled the plugs yet?

[cheapscheisst]

yeah 1-3 were fine, 4 wasn't gapped correctly, so i adjusted it and reinstalled. Now the idle is better when the car runs correctly, but it doesn't make a difference when the car has this problem.

[Emperor_Tha]

possible bad gas if its random. Disconnect the fuel and dump the fuel into a bottle. If the fuel looks cloudy its no good. It has to be a transparent I would say a very very light tanish/yellow color.

[cheapscheisst]

gas is fine. i've been running 93 solely from BP for a year, and i just filled up the other day.

[cheapscheisst]

also i forgot to mention that compression is 135 across the boards, so no issue there.

[IDriveFords]

sounds like a faulty coil pack, when it starts doing it just pull the coil packs one at a time and if the sympton remains the same when you pull a certain one then you found the faulty one if it gets worse or stalls then you got the wrong one. For instance if you got 1,2 and 3 hooked up and you pull 4 and the symptom doesn't get any worse or better than 4 isn't firing or improperly firing if it gets worse or stalls then plug 4 back up and see if it goes back to how it was. Just make sure you always have 3 of the coil packs pluged in b/c trying to make the car run off 2 cyls will most likely just make it stall and you won't be able to tell. This is the easy way to check and figure out which cylinder isn't firing properly you could also use a test light but thats a little harder to do with coil packs. I doubt its the ignitor chip b/c that will usually cause it not to fire at all. Could be a wiring or ECU problem but checking the cylinders is a start at least. Just don't put your hands under the coil where it hooks onto the spark plug, but thats just common sense.

[cheapscheisst]

that's the first thing i did when it happened. nothing. when i say it's misfiring badly, i mean BADLY. i've had a bad coilpack before, and that ran 100X better than it is now. honestly you could barely tell a difference when any individual pack was pulled.

[Silvia_sr14.5]

My first instinct is that it is your maf sensor. Check the wires to your maf sensor, and also maybe try another maf sensor.

[TK_Encore]

sounds like the same problem im havin(no sr yet ) but still sounds like the exact samee thing, when u figure it out let me know so i can try it on mine

[driftset]

same here i can actually hear a feint miss every couple of seconds throgh the exhaust , so if i tilt or move my mafs it gets worse...im going to open it up and see if there are any debris in there just wish i could swap it out with someone elses real quick but im the only SR for miles...il let yous know gl

[arauz]

wow, you guys too. Same thing has been happening with my kouki (ka) for about 2 months now. What I have pinpointed on mine is that it only starts misfiring after I've been driving for about 20-25 min. I guess when the engine reaches a certain temp??? When I check codes I get Knock sensor and crank angle sensor. I'm gonna check the coilpacks tom, who knows maybe that's it.

[SuicidnS13]

same here i can actually hear a feint miss every couple of seconds throgh the exhaust , so if i tilt or move my mafs it gets worse...im going to open it up and see if there are any debris in there just wish i could swap it out with someone elses real quick but im the only SR for miles...il let yous know gl

Just switch it over to a sohc maf from a ka24e. Wiring guides are all over the place. And your car will run of it. Ive had a sohc maf to just over 250whp for over a year now.