Rb25Det High Idle

[doybe]

hi there, ive got an rb25det c33, did he whole conversion in my garage, auto to manual, adjusties exhaust and all, minimal tools, no experience just alot of reading. car started first pop and ran mint for a bout a year now. ive just put a greddy style front facing on and its idleing high. i have spent weeks trying to fix this, ive checked and cleaned iac valve, removed cold start all together, tested for vacuum leaks a million times, throttle body is completly shut yet it still idles at 2000 and is always hunting and miss-firing. if i block the hose to the iac valve the idle will drop to about 1000 but as sson as i touch the throttle again with the hose unblocked it jumps back up. any help or brainstorming on this would be really appreciated

[doybe]

also, because i got the 80mm TB i had to change my tps, ive doubled checked all the wiring and everything ive done but i think i may have done something wrong because at idle it reads almost 5v and goes down to about 1v and full throttle? its all backward but cant see what ive done wrong, maybe its the wrong tps?

[Got a Pulsar]

What happens if you switch the wires around?

[doybe]

as in, swap the constant (5v) with the signal (should be .5v)? the tps is just something ive noticed, but nothing changes with the idle if i unplug it. but as for your question im not sure i will have to try it and let you know

[DVS JEZ]

Have u confirmed the tps is set correctly now? If its not than the ecu doesnt know that it should be idling, and uses higher timing numbers which keeps engine revs higher

[doybe]

oh yea cheers for that, im ggoing to get a new tps and quadruple check the wiring, cheers

[GTSBoy]

Nissan ECU wants to see about 0.45V at idle, throttle closed. You could get yourself a variable resistor, wire it across the TPS connector and adjust until you measure 0.45V going back to the ECU, see if the idle drops to something more reasonable.

If you have a Nissan TPS on the car now, and it is reading 5V closed and 1V open, there is something rather wrong with the way it is wired up. I'm not even sure if it is possible to wire one so that it does that.

[doybe]

yea thats what i was thining, its like its zeroed out backward or something, im pretty sure its off a maxima but cant imagine why that should matter

[doybe]

ok everybody, so ive sorted my high idle, after a few weeks of goin over all my wiring and valves, thinking i had done something wrong, i realised the tps was working backward, i could see any scenario where my wiring could cause this so got my mate tps from an r32 and as soon as i had the 2 side by side, i could see mine was different. my pigtail was on the opposite side, and on the steel side of the tps there is an arrow, mine pointed anti clockwise i think and his was the opposite, sure enough plugged it in and bobs your uncle, low smooth idle again. so for anybody wondering, your tps does matter, mine was from a maxima, didnt work, hope this can help someone in the future, thanks everyone for your help

[Got a Pulsar]

so switching the wires should work like I suggested.

[GTSBoy]

No it wouldn't work. The variable resistor inside doesn't work that way. Think about it.

[doybe]

cant see how switthchin the wires would work, like gts boy said, variable resistors dont work that way, but hopefully the wrekor will have the correct tps tomorow and i can put my br an rack spaers in and get back on the track. such a stupid mistake cant believe it got the best of me for almost a month haha live and learn

[doybe]

ok, i lied, swapped the tps over today, car drives a million times better, can now go foot flat without it dieing or studdering. managed to get it to idle at about 900 -1000rpm, but it slowly creeps up to 2000rpm. this is driving e insane, quick question, the vac line from roker case to plenum has a litle valve on it, should this be leeting air from the cover into the plenum at idle? i messed with cas a bit, nothing, swapped AFM, still no change, also my ecu doesnt have an idle screw so that sucks. i am litterlly open to any ideas no matter how wild they are

[DVS JEZ]

Where are u located?

[R33_gtst96]

did you have any luck with this? I've got the exact same issue r33 rb25det with greddy inlet plenum 80mm throttle body brand new S1 TPS idle is all over the shop, sometimes it idles great about 700 then other times between 1500 and 2k even when driving it bogs down now when accelerating from start but when you turn the car off and back on it runs fine. going to powertune on Thursday to see if they can shed some light on it for me

[doybe]

im located in nz mate, so i got a new tps tuned it in and the car drove gret apart from the idle still being high, took the tb off to have a proper look, found the only way i could get it to reallu seel was if i let it ping closed at speed, but then it would also stick shut, so i got a new tb sent out to replace the old one, and iwith a bit of time setting and loctiteing everything just right, ive now got my car idleing at 600 which is really nice and low, it hunts everynow and again and sometimes dies when u let the revs off but a bit of playing around should fix this, confident ivegot it sorted now, cheers everyone