WIERD problems with the RB

Discuss the RB20, RB25 and RB26 series engines.
xDRFTurR1D3x
Posts: 131
Joined: Sat Jan 20, 2007 10:58 am
Car: 98 kouki- S2 RB25- f*ck you fed ex and mother nature!
93 s13.4 kouki/coupe- bottle fed modded KA- VH45 almost ready!
Location: the garage

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Freaking god... who needs a girlfriend when youve got an RB. SO freaking moody!

So the koukis been running perfectly fine the past couple of days. Exhaust appt didnt work out the first day so i went to take her back yesterday and i started having problems.

Car starts bucking a kicking anytime i give it gas... will be driving fine then the sound of the motor gets sort of muffled, no throttle response watsoever then will come back .. then go out then come back . Then wont rev past a certain rpm. i dont know WAT that rpm is since my tach hasnt been adjusted yet for the rb. it SAYS somewhere around 3750 or so. acts just like a maf problem. so i stay uner that rpm until i get it home. then it starts bucking kickin and bogging if i give it any gas watsoever above id say a quarter throttle. barely gets around if i go any mroe than that or punch it it just hiccups pops, backfires etc. Then it dies at the light. starts revs up a little then dies,,,, repeatedly. finally get the piece of s*** to a parking lot. still wont start. let it sit for five minutes, disconnect the battery etc. starts right up drives PERFECT idles smooth boosts etc. get two blocks down the road and starts this bulls*** all over again. so i take it home an get the only good news out of it for the day. the compression nubmers went up!

130120125120125130

after the compression test i reroute the harness along the fuel rail for a cleaner look. then she runs PERFECT for four hours straight just riving around not getting on it or anything. then starts in again. Kicking bucking nothing above a certain rpm . acts JUST liek a maf problem. but if it was a maf problem it would do it all the time not just work when it wants to. i dont freaking get any of this s*** and all these problems are getting EXTREMELY old. nothing new has been done except the compression tests, harness rerouting and installing an aftermarket temp gauge in the radiator hose.(which doesnt even work ). starts and idles smooth revs iup to a certain rpm then bounces off of it. sometimes wont start at all but only after driving it and starts acting up

soo couldnt be the maf or it would be messed up all the time. thinking possibly the harness since it acts like maybe a ground? or a wire grounding out ? theres a bundle of wires by the ecu that arent connected to anything but have yellow duct tape with numbers on them. i assume these wires are supposed to go to the related pin? this harness was supposed to be done completely and everything working. clearly it does not since two of these wires i identified as my coolant tempo wires. im sure the others are my damn wipers prolly even vct and god only knows wat else.

my other thought is safe mode? but for some god forsaken reason S@ rb25s dont have diagnostic lights on their ecus. so i cant tell if its in safe mode or wat codes its throwing.

my three thoughts IF its safe mode areMaf sensorCoolant temp sensorKnock sensors (since i had to make my own knock sensor harness but they are getting power?)

but all of these would have affected it on the way to the show on expressway. so im completely at a loss and WAY past frustrated to the point of giving up,

only two things i can think of is putting the loose wires where they need to go, throwing the Z32 mf with the neo i have to see if that changes anything, if none of this changes anything im thinking pull my harness tear it apart go through and connect wat needs to be connected. since i knwo wat plgus are used now and wat arent take out wat isnt needed etc. if NONE of this works after checking grounds and wat not.... i really do not know.

also vids are on my cell. ill post them when i get back from cursing her to death.


User avatar
Carl H
Posts: 5985
Joined: Mon Aug 04, 2003 4:09 am
Car: 1995 Nissan 240SX SE RB30DET

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sounds more like a boost leak to me honestly.

whoareu
Posts: 163
Joined: Fri Aug 01, 2008 6:09 am
Car: 1993 rb25det s2 240sx vert
Location: Beaufort, SC

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did you ground out the sender housing for the temp sender? also it does kinda sound like the ecu temp sensor in that once it gets up to op temp it starts acting up, i recently replaced mine, there pretty cheap you can use one from a 96 maxima i beleive.


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