1jz rough idle/misfire

[disc0-dan]

Hi guys

Need some guru assistance as im a newb as far as toyota's go, so please solve away :-P Ive recently aquired a gx81 thats had all changes made to swap it to a jzx81 with a few small issues i will begin to describe.

When i start the car ( cold start ) it will idle extremely low and stall if i dont tap the gas to keep the RPM up. Originally thought it was a vac issue but i cant seem to find a leak. Now when driving while the car is still cold it will miss between 2.5k and 3.5k RPM causing a bit of a splutter. Once it pushed past this RPM or under heavier load it goes away. The issue with the miss goes away once warm also.

Next one which is the strange one while cruising, for example at around 60km/h to 70km/h or just driving along with very light thorottle pressure the car seems to cough and splutter or miss even. Also when backing of the cars seems to backfire/pop quite regularly. Again under load there are no problems.

The other night while trying to check all vac lines and just a general once over of the engine bay i knocked the loom and the car almost stalled and if i jiggle it it occasionally almost stalls or drops RPM.

My thoughts were :
A) coil packs
B) poorly gapped plugs
C) fuel pump/pressure
D) fouled injector

None of which i have checked yet and will be trying to get plugs out this weekend at some stage, but if anyone has any idea's or had similar issues let us know !

[88cameron88]

sounds like a wiring issue, if you jiggle the loom it causes the issue.
could be a nearlly broken wire to a coil or to the ignitor. general vibrations while driving might be causing it to drop its current.

[forey]

Hi guys, after doing a lot of research on the net, I have this exact same issue, random intermittent miss at idle, load+boost will splutter and carry on, but will clear itself higher in the rpm range??, anything higher than 10psi will miss big time

Problem seems to be very low load, midrange is pretty spot on (without boost) , and missing with boost + load

Any ideas? Coil pack clips are broken and could be replaced, what about igf signals to the ignitor? I did have a problem with the engine fully cutting out at times ( fixed with a proper ignitor ground) what about injector plug wiring?

New plugs and having them gapped doesnt really make a difference

Running standard Ecu + emanage, although has worked fine until very recently

[masterofsinanju]

http://www.toymods.org.au/forums/eng...z10-guide.html
Check out this thread. There are a couple of posts that mention what sounds like your problem (minus the jiggly wire cutout issue) and it migh indicate some issues with your ISCV.

Jiggly loom cut out sounds like a seperate issue.