View Full Version : rb20, pulls like a camry on 2 cylinders aka nooo ballssss. WTF

01-29-2012, 10:23 AM
heres what i got,

Stock rb20 maf

Stock rb20 turbo

running from said turbo is

just your average FMIC

also im running

Normal 240 fuel filter

step hot, number 5 NGKs

kay, now car idles fine and revs up fine.. but feels like its breaking up in high rpm when you rev it, when you actually drive it, its revs to like 3000 rpm and builds boost and instantly falls on its face.. within 3psi it just pulls like.. nothing.. i could get ran by a middle schooler on a bicycle. i have a little vac leak somewhere i can here that but its very small and i still have about 20psi at idle. im thinking there is a boost leak somewhere and the hotter plugs may have something to do with it as well.. car had a 300zx fuel filter but i had a brand new 240 one so i threw it on, would that make a difference?

01-29-2012, 11:20 AM
Yes put a z32 fuel filter back on.

01-29-2012, 11:23 AM
You should be running ngk BCPR6ES-11 plugs gapped at 8mm on that motor

Im running a stock rb20 on stock 10 psi with front mount, 3" dp and wasted spark and my car runs like a raped ape ( makes 246hp n 220tq to the wheels )

You might be having spark issues if your plug gap is wrong

Also do you have your speedo wired in? If your using the wrong vss it could be tripping the speed gov.. Sounds dumb but a swap I just did had this issue so I cut the speed limit wire and no more issue

So look at those things and see what you come up with

01-29-2012, 12:36 PM
Its timing. Fix it. Search how to do it properly.

01-29-2012, 07:13 PM
rb20240sx - yes i shall, didnt think it would make a difference being smaller but maybe it does? restriction or something?

N2HIFI - i have 6's to swap back in i had an issue with it that i have since fixed, but i needed the 5's seeing as how i could keep it running and diagnose and later fix that issue. my gap is definitely a little off i didnt really measure it just gapped it in a little so ill do that more thorough, as for the speedo, i just have an s13 speed sensor with all stock wiring with tach adapter and all that jazz. could that be wrong? thank you for the suggestions! keep them coming!

ch1873857 - unlikley, the motor was pulled running and just swapped to a different shell, and it runs smooth at idle with perfect vacuum. out of time and it would have a slight misfire and vacuum would be slightly less. its literally ran flawlessly before swapped only thing changed was plugs and fuel filter so ill start there and see what happens

any one else feel free to add! thanks everyone so far!

01-29-2012, 08:07 PM
knock sensor can do that, check to see if its even plugged in. Verify continuity at the ECU for that white wire by consulting an ECU diagram. last case scenario exchange it for a known good one.

01-29-2012, 08:36 PM
Dude. Telling you from experience. Could be 2 things. Plug gap. Or timing. My car idled like a boss. Slow as piss under boost. Timing was off. Just re read that you changed the plugs. Did you pull the gap down? Because out of the box its too big..

01-30-2012, 07:38 AM
Ill check knock sensor.

My plug gap is a bit large I believe from looking at it they are loosely gapped at like .035 what's factory? Like .020 right? Ill do that then check timing Just to be sure what would it hurt atleast ill know for sure if it is indeed timing or not

01-30-2012, 08:51 AM
ooh yeah. my last rb25 had this problem. i couldnt believe how much plug gap made a difference. good luck!!

01-30-2012, 10:25 AM
Thanks dude! Hope it helps

01-31-2012, 01:08 PM
hmm changed the plugs back to my 6's and gapped that at .8 and it was misfiring so i changed one of my coilpacks back to stock and it ran better at idle. and revved more smooth but now it idles rough and it still wont move underboost it just stumbles real bad and slowly builds boost and trys to go. feels like a mixture of misfiring a little and a massive fuel cut. only thing i havent changed is the fuel filter back to a z32 maybe its choking it of fuel?

01-31-2012, 06:50 PM
Boost cut? seriously sounds like timing issue. Have you checked it

02-01-2012, 06:49 AM
Ignition timing? I can check that but it misfires so my luck ill pick the cylinder misfiring and fuck it all up -.- I was researching boost cut yesterday. I have a pretty good size vac leak you can hear it at idle just didn't think it was big. Ill pressure test it and hit it with a timing light and check back in

02-01-2012, 08:31 PM
I have no idea what's wrong now.. seems like when you drive it and let it get warm it gets worse and worse.. random misfires.. all over doesn't idle good now.. I've switched coils and shit I don't know.. runs terrible now.. I don't get what could just make it run like shit all of a sudden.. it actually felt like it tried to pull a little today but then got worse.. like basically Just had enough power to get it up my driveway vacuum drops idle gets rough missfires big problems.. I'm kinda leaning towards timing now too although the motors never been apart. Ill have to check. Sorry for the rant just frustrated hah ran perfect now runs like garbage

02-02-2012, 12:51 AM
Unplug your maf see if it fixes your idle problem. Cant hurt

02-02-2012, 08:49 AM
If that helps I know its either fuel or maf. So that'd help. I did take it apart and solder the connections back but I'm not a newb.. lol so it should still be fine that's all I did. Ill check

02-02-2012, 09:18 PM
i had this exact problem in my 87 supra. power till 3k and then flatlined________________. do yo notice any kind of oil in the spark plugs?? if so your valve seals could be going bad allowing oil into the spark plug area. probably not, but hey its a mystery so far XD

02-02-2012, 10:27 PM
Finally got my boost leak tester to work.. -.- it was a gigantic leak on the intake manifold.. feel so dumb.. sorry guys :( lol

02-08-2012, 09:30 AM
At least your back up and running!

02-08-2012, 09:36 AM
fuel pressure regulator or fuel filter. Did you swap the fuel pump from the other car also OEM fuel pump will not be able to supply the engine.