1jz issues

[orangeute338]

hi guys, im having some dramas with my soarer.

history of the car
gz20 soarer with jzz30 1jz and 1j/2j hybird auto
twin 3inch intakes
3inch exhaust decated
everything else is stock

car has been having a problem where it seemed to be fuelling up at anything above slightly throttle and below half throttle, would be cruising at part throttle and push the pedal down a bit and it would start to struggle and if held it for long enough would start to fart and pop and backfire, but if i pushed the pedal further past roughly 50% it would be perfect. Made me think the o2 sensor was playing up which over 50% wouldnt be reading o2 so was going ok?, i checked the voltage at ox1 port on the test plug and the voltage was 3v so ordered a new sensor thinking old one must be shagged.

then all of a sudden the next time i drive the car its swapped, car drives fine anything below 50% throttle, voltage at ox1 reads .6v at idle. now if i give it anymore then roughly 50% throttle it will fart and pop and wont rev. i can get it rev right out if i dont go over 50% so its not happening at a certian rpm....its worse in 1st,2nd, 3rd i can get almost full throttle if i go slowly...

just wondering what i can check, i have set the tps, will check it again with the feeler gauges, i did pull no.1 plug out and it looked fine my coils have been glued together, so maybe one has broken again?? or maybe the ecu is dead?

i havnt got the new o2 sensor yet but will change that when i get it...

thanks for any advice
cheers
Josh

[Johnny stav]

Hey mate id check for boost leaks first all your intercooler pipes ! then pull the coils out heat shrink the bottoms of them if their is cracks ! what plugs do you have in it ? Also the rear cam angle senser does it have oil in the plug , that is also a common problem on 1jz . Try all of those and if it doesnt work contact me and ill give you some more advice

[dumbass]

pull lids of ecu and look for leaky capacitors
its easier to check tps with multimeter and test light
test light for idle switch ground and same time use
multimeter to set tps signal to around .6 volts at idle

[dumbass]

also unplug tps and drive it and see if problem gets better or worse

[orangeute338]

i redid the tps this morning and its all within specs, went for a drive now the problem is back to normal, over 50% throttle it goes hard and anything under it farts and lags untill i push it through to over half throttle. i just checked the ox1 again at the test port and was reading .9v so not sure why the other day at work i got 2.7v and later that day i got over 3v at the same ox1...seems to be ok now...

the coils have silicone all over them cos im guessing they are all cracked. i will have a look at the ecu again last time it looked ok, will set up the wideband and go for a drive and see whats happen also, theres no engine codes coming up, i havnt driven with tps off but if i unplug it at idle it runs crapper...

how does the idle control valve work? i have a filter on it instead of plumbed into the intake...that stages is it open closed etc? maybe its sticking open or something....i cleaned it out a few weeks ago

[orangeute338]

i went out for a drive, it seems like (roughly) less then 20% throttle is fine 50%-80% is fine and anything inbetween is crap..so i pulled the tps plug off and the prob is gone..woo hoo win...only prob is with tps unplugged the auto doesnt shift all that good, but the studdering and lagging went away and went like normal...so my tps is dead? what you guys reckon?

[orangeute338]

just a follow up for anyone that comes across this thread with the same problems.

replaced the o2 sensor with cheap universial one off ebay and problem is sorted. cars drives perfect now. doesnt stink now either...

problem with it cutting out at wot is it is hitting boost cut, because i have twin 3inch intakes and 3inch straight through exhaust guess its overboosting to much now...mostly happens in 1st and 2nd...

thanks for the replys