Spontaneous Misfiring

[240dreams]

This is a copy and paste from my FA post:Alright heres the deal, spontaneously my car started to run like crap and idle very rougly. I checked for codes and I got a code 12 (MAF). I tried swapping out my MAF with another one of unknown condt but that didnt work. Same issue. I unplugged it and idle dropped about 200 rpms and it wouldnt rev past 2k or so. I tried cleaning both of them and everything but got nothing. I even tried to reset the code but it never went away. My car bogs and misfires pretty bad at all rpms - even idle. I know for sure it revs past 4.5k so I know the wiring cant be bad. Also, Ive been running the same wiring for about a year now. If someone can point me in the right direction to fixing this issue, I'd greatly appreciate it. Thanks in advance.

I forgot to add readings from my SAFC sensor check:Car off:In-1: .78vIn-2: .02v

Idle: In-1: 1.5In-2: .035

2.5k rpm:In-1: 1.99vIn-2: .045

Alright, I just swapped in my z32 MAF and I still have the problem only not as bad it seems. The Safc still reads an airflow percentage. My peak on the test drive was 40% at 6k rpm. The car seems to run fine under a light load like around 20% throttle. I traced my wiring back to the ECU grommet on the firewall and it seems fine. I didnt make any changes or alter the wiring at all so I dont think its a wiring issue. Again, Ive been running fine for about a year now and all of a sudden I get this - code 12. I tried resetting the ECU, disconnecting it, and unlpugging the battery. I still get a code 12. Any help would be appreciated.

Ok tonight, I recleared the ECU code and it went away. But, the problem didn't. Still bogs and misfires. I'm starting to believe that the problem may not even lie in the MAF. I changed the spark plugs to my old ones which worked fine when pulled. Problem still there. I listen to the injectors clicking and they all sound the same. I listened for the fuel pump and it still hums. After clearing the code 12, I got a code 55 (all is good). Can there still be other faults? What else should I look into that may be related to my problem? Thanks.

I just checked the coil packs according to the FSM instructions. All of them read .9-1.0 ohms. I also unplugged each of them during idle and they all made the engine shake when disconnected. Can the ignitor be bad?

[180fan]

Did you check each plug for spark or check them for fuel after running the motor? If one or more are, that'll tell you about which cylinders are causing the lack of fire. If they are all firing, I'd check the ignitor's circuits. If the ignitor comes up ok, it'll be your CAS. You can find the diagrams/how-to check on your ignitor. You will need a multimeter.

[240dreams]

When I first swapped plugs, they seemd fine (grayish-whitish color, dry). I checked the ignitor and it passed the FSM test. Ill have to check my CAS.

[240dreams]

Also, I checked my injectors according to the FSM and they came up fine too. Is the resistance check any good? Can it determine if the injector is stuck open?

[180fan]

http://www.pdm-racing.com/features/plugs.html

any of those fit the description of your plugs? I think the injectors resistances can be checked if they're shot or not. But if they're clogged, might wanna just send your injectors out to rc engineering for cleaning.

[240dreams]

My plugs were very white at the tips of the core (the finger like thing). Other than that everything matched up like the normal plug. I just bought a new fuel filter and Im going to put it in tomorrow just to see if that does anything. I'm pretty sure it wont b/c the problem seems to be too much fuel and not fuel starvation. Im not sure at all really. Gonna try some new things tomorrow.

[ChachiS13]

check and make sure your settings are correct on your SAFC, there are times when mysteriously, the setting change and the sensor types are not correct. Happened on my car one day at a stoplight and it started to run like crap after I stalled and was running DAAAMMMMNN rich, fouled my iridiums instantly. Drove everyone nuts for a week cause we couldnt figure it our...then though hey, let me check the settings and sure enough, the sensor settings were off...wierd happened out of nowhere and cause the car to run rich cause the settings were for a different type of sensor

[240dreams]

My settings are all correct. Thanks though.

[S13CoupeLuvr]

I believe I have the same problem with my SAFC. My car also just started running really rich at a stoplight and Iv replaced everything that could cause the problem. I did notice that some of the settings were wrong on the SAFC but Im not quite sure if all of the sensors are set correctly. The car shakes when parked and is EXTREMELY slow. could someone tell me what the sensors should say on the SAFC?

*sig is for a different car, This one has: sr20det, blitz BOV, 3"downpipe+cat+catback, walbro 255

[getnrowdy23]

i believe the afc needs to be changed to 2in 7out for a z32maf

[240dreams]

i believe the afc needs to be changed to 2in 7out for a z32maf

for a z32 maf its 2 in 6 out

[240dreams]

Just replaced my ECT sensor and the problem is still there.

[240dreams]

bad coilpack on #1. for those who search and find this thread.

[Rican_Nick]

bad coilpack on #1. for those who search and find this thread.

hmm would a bad coil pack cause u to bog misfire from 3k-4k? its driving me crazy right now.. it happens on and off but lately has goten worst.. with new plugs the problem gets resolved for a week or 2 and then its back at it acting up. i have suspected the coil packs and the TPS.. i am testing the TPS this weekend. How did you test ur coilpack? or did u just replace em one at a time?

thanks in advance.

[240dreams]

i tested them by unplugging them one at a time to see if they made the engine stumble or not. if they did, that means they are good. i also tested them according to the fsm by checking resistance. they came up good. but for some reason i had a doubt about them. electrical parts can go bad after a certain operating temp. i had every reason to believe that they were bad according to the symptoms. so i went ahead and replaced all four from my friends sr to mine. ran beautifully. i bought 1 coil pack from a friend and just went through each cylinder to see which one was bad. i got lucky and got it on the first try cyl #1. i put the old coil pack back in and it ran like crap make sure. hope this helps.

[Rican_Nick]

i tested them by unplugging them one at a time to see if they made the engine stumble or not. if they did, that means they are good. i also tested them according to the fsm by checking resistance. they came up good. but for some reason i had a doubt about them. electrical parts can go bad after a certain operating temp. i had every reason to believe that they were bad according to the symptoms. so i went ahead and replaced all four from my friends sr to mine. ran beautifully. i bought 1 coil pack from a friend and just went through each cylinder to see which one was bad. i got lucky and got it on the first try cyl #1. i put the old coil pack back in and it ran like crap make sure. hope this helps.

sure does .. i too think i am having coil pack issue after a certain temp. Gonna try it this weekend.