Mysterious Pfc Missfire In An R32 Gtr

[mico]

mine has just started doing this all of a sudden, straight after i removed everything from under/behind the dash. REALLY bad. hardly drivable. hasnt been tuned yet but it is very intermittant. power fc d jetro with gt35. im going to do the grounding thing and turn off o2 sensors. cas tps etc is fine.

[DVS JEZ]

Maybe get a tune 1st.

[paulr33]

you say all of a sudden, yet you mentioned it only occured straight after you pulled everything out from under the dash - conincidence you think?

double check whatever you did and triple check it - it might be something obvious or loose that is causing a bad earth. given it was fine before you started fiddling its a high possibility whatever you were doing has caused it

[mico]

by saying all of a sudden i indeed meant straight after i removed everything im thinking that all of that stuff could have helped earth the car. i know it really needs a tune just waiting on a clutch. one other thing i did b4 going for a drive was alter the cas and cam gears. but ive done this b4 and it had no such affect.

[DVS JEZ]

Haha. Come on man. U changed heaps of things. Cam gear timing and crank timing is major. Did u have the ecu before or is it new to the car?

[mico]

nah everything is brand spankers and i done all the work, but it never did this until i removed the dash the other day. ive also moved the cam gears to where they are now (0 degrees) and was never like this. when i started the car up it almost felt like the accelerator had no effect for a bit. i think im goin to change the cas cos thats the only thing i can think of doin this.

[DVS JEZ]

What did u remove from under the dash?

[DVS JEZ]

By changing the cam gears u affect the tune alot with a d jetro due to the map sensors, if it was using airflow meters it wouldnt be as bad.

Try pitting the cam gears back and see if it fixes it. Then readjust them when u tune it

[mico]

well its running beautifully now and i think it was the cas. when i took it off to put the cam gears bak to 0, i left the actual cas on the mounting bracket so it didnt move. but when it goes bak on its hard to get the keyway to line up perfect. i think it was sitting out a bit and the keyway not locked into the grooves ... one other thing it could have been was the aftermarket oil pressure sender, it has only one pin for the light. i unplugged it this arv and im going to get a new stock one. oh and the dash was removed to take out the heater core, a/c condensor and fan.

[extraction]

well its running beautifully now and i think it was the cas. when i took it off to put the cam gears bak to 0, i left the actual cas on the mounting bracket so it didnt move. but when it goes bak on its hard to get the keyway to line up perfect. i think it was sitting out a bit and the keyway not locked into the grooves ... one other thing it could have been was the aftermarket oil pressure sender, it has only one pin for the light. i unplugged it this arv and im going to get a new stock one. oh and the dash was removed to take out the heater core, a/c condensor and fan.

Can anyone confirm if the earthing wire solution fixed the issue? If so could somone take a pic for me showing me what needs to be done as I have this issue ony my 32 gtr with a power fc.

[Kaido_RR]

interesting topic, is this issue only related to normal pfc?

I am running dejtro in r32 gtr and have missfiring issue under light load.

Have replace spark plugs, coil packs, coil pack harness. it went away but has since come back

seems to only happen atm when downshifting + rev matching, low rpm from what i notice under 3000-4000rpm, currently running with o2 sensors off

had a chat to my tuner and he wants it back on the dyno to see if its tune related

[R31Nismoid]

It's a random thing.

Not a constantly repeatable one.

If you can force it to occur, then you've other issues than the ECU having a minor hiccup due to the addressing once every so often

[Kaido_RR]

It's a random thing.

Not a constantly repeatable one.

If you can force it to occur, then you've other issues than the ECU having a minor hiccup due to the addressing once every so often

doesn't happen all time just now and then, i just notice it mainly happens in low rpm and light throttle.

will get it on the dyno to double check the tune, and might try some of the grounding issue.

the only other thing i can thing of if its not the pfc then i might be the box mounted on the coil pack cover (forgets its name)

[extraction]

For me it sounds like what other people have. It just seems to randomly happen maybe once a week and it typically seemed to happen when cruising on the highway around 100km sitting just under 3000rpm, it feels like a sudden jolt but only happens for half a second and returns to normal.

[mico]

nah mine was an extreme surge. im pretty sure it was my cas.

[trick]

ive had similar issues with power fcs and earths (http://www.skylinesaustralia.com/forums/topic/349571-erratic-tps-34-gtr/, earthing pin #60 of the ecu to the chassis ground had a physical effect on the voltage to the problem at the time. clearing the signal to the atessa. its a simple job. could fix the stutter issue of the fc

[Pal]

hey guys, sorry to open a old thread but having this problem at the moment. done a service (plugs and oil) on my r33 gtst with PFC and now having this intermittent miss. thinking i had a bung plug i changed all the plugs but it is still there. ok under power but has little misses at about 80km/hr under light load. did other guys sort out there missing problems or is it still common. im about to rip out the coil packs and get them tested but i dont think its them as the car run ok before the service and is fine under load at high rpm. im going to have a look at the earthing of the igniter module as well. any other ideas. cars got following mods

pfc

high flow turbo

550cc injectors

hey guys, fixed the problem on my old gtst(ended up being a loose injector plug) BUT my GTR is doing it, same thing, intermittent hiccup when cruising. have extra earthing wires everywhere under the bonnet but still there. ???

[jetdriver]

Has anyone tried to get a fix out of Apexi. Surely with such a well documented problem they could come up with a remedy in the software. I have this problem about 3-4 times a day on my rb25 running a v8.04a rb26 PFC. Always light throttle, and it seems like when adding throttle, it feels like you turned off the key for half a second. I have added a ground to the ignitor case, but have had no change.

[DVS JEZ]

Good luck getting a reply from them. There

Shut down.

Have u had u cruise tune checked?

Try disabling the 02 feedback and see if it still happens

[jetdriver]

Strange, Apexi USA is still open, and the Apexi Japan site is up. I always have the o2 feedback off as I have not finished the tune yet. I had a SR20DET before with a PFC without this issue. I am using the same TPS and Z32 AFM as before, so I do not suspect them to have any problems.

Edited August 1, 2011 by jetdriver