rb25det doesnt feel powerful

[xr504]

Hello guys. I recently just got my rb25det swapped into my s14 from another wrecked s14 i had bought for the motor I am new to rb25det's but have had a few other turbo cars so i kinda know the basics. It seems to run pretty decent but what i do not understand is it does not feel very powerful after it starts building boost. It is pretty much stock other than 3 inch exhaust all the way back, Front mount intercooler, replaced turbo inlet gasket and valve cover gaskets befor putting it in the shell, and thats about it that i know of. It also had a manual boost controller in it and was running around 9psi. The other day when it would get up around 6-9psi for a few seconds the turbo would cut out real quick and drop to no boost then jump back up. I took out that boost controller and replaced it with a Blitz spec r ebc and it seemed to eliminate that problem. i am currently running around 9-10 peak psi and seams to build and hold boost fine but the thing is when it builds boost it does not seem to have the power i expected for running 10psi, it bearly if at all even puts you in your seat. I have had a turbo mr2 running on 15psi without any other mods other than exhaust and intake and it was twice as fast, and befor i bought the s14 i had a little d series del sol with just a ebay turbo kit running on 6psi and it was even quicker than this. i have checked the intercooler piping and there does not seem to be any leaks. the motor tho did have a pretty bad hack job in the wrecked s14 i bought so i am slowly cleaning it up but i do not see anything really that would cause such a lack in power. Also it has a mishimoto radiator with one puller fan but the fan hasnt been hooked up yet and the hottest i have yet to see it running is around 145-150f, from what i read is its suppose to be around 180f. So what i would like to know is if anyone with rb experience could give me some advice on wat to check or what could be causing these problems?

Thanks all

[frftw]

check mechanical timing. did you check spark on all cylenders? also check for boost leaks, this gave me hell when setting up my ca

[smoked240]

Obviously a del sol would feel quicker, They are light cars. Like Frftw said, check timing, boost leak. I'm not sure what the best time to run it at, but I hit 245F with mine and it pulled hard. Are you running the stock fuel pump? Fuel pressure regulator? maybe it could be a clogged filter. Just throwing out options.

[xr504]

Thanks for the replys. ill check that stuff on Friday. It has a walboro pump and not sure about the fpr

[R33E8]

do you have a wideband? what are you're afr's?

[Sileighty_85]

Check/ Replace spark plugs, Gap them at .028
Clean MAFS

and make sure the engine is reached optimal temps, I noticed mine pulled alot better when i got my temps to stablize around 80*C
before it was around 70*C

[xr504]

Im waiting on my plugs to get here. hopefully will be able to change them in the next few days, but from wat i was reading i should gap them at .8mm? and how could i get it to run warmer? its only running around 140-150*f which equals 60-65*c and im not even running my electric fan. the only thing aftermarket that i know of cooling wise is the mishimoto radiator. R33e8 i do not have a wideband and i am unsure of the afr's

[Sileighty_85]

I tried them at .8mm but It would break up under high RPM and blow out my spark over .7bar So i gapped mine down to .028 and it runs alot better

What gauge are you using?
do you have a thermostat in the engine?

[rb25_s13*CHUKI]

check plugs. gap the plugs at .026 or .028 . check for boost leaks, try adjusting your cas and check mechanical timing... cas cas cas cas cas cas cas cas cas cas cas cas cas. timing is retarteddddddd

[xr504]

It's got a cheap prosport gauge in it and its just tied into the cluster temp sensor wire, probably not the right way but that's how it was wen I got it and haven't had a chance to get a new one but if anyone has a decent gauge for sale let me know. As for timing goes does anyone have any tips or links on how to check it and adjust it? I have never messed with timing on anything before

[Sileighty_85]

that def dosent sound right on the coolant gauge.

the gauge should come with it own sensor. if it uses any other sensor then its not gonna read correctly.

as for the CAS timing the CAS can only go in one way the bolts should sit almost in the center of the slot

http://i73.photobucket.com/albums/i235/Neil_85/FAST/cas.png

[rb25_s13*CHUKI]

Post up a picture of how your cas is set. If its turned too much back you'll feel a huge loss in powwer and simply advancing it forward would bring your engine to life

[xr504]

alright i checked the cas and it was almost center, and i tried to adjust it to be more center but couldnt really get it dead center. it seemed like wen i got one center the other two were off a little bit. but here is two pictures of it. the first one is the bottom bolt24269

[Sileighty_85]

timing seems about right

I would look into the spark plug gaps and the engine temp

[xr504]

ok. still waiting on plugs. should be here by monday i hope. do you guys no of any decent temp gauges for a decent price? have you had any experience with glowshift gauges? becaus the other two gauges are glowshift and would prefer to have them all matching if there temp gauge isnt bad

[Sileighty_85]

heres some better pics (this is the top left bolt)
http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5312.jpg

http://i73.photobucket.com/albums/i235/Neil_85/Miyukis%20Silvia/DSCN5313.jpg

ultimately a timing light would be best but if you dont

[xr504]

ok thanks. ill see if i can get my hands on a timing light tomorrow. Also i forgot to mention that my O2 sensor is broke, one of the wires is broke. could that have anything to do with it? and does anyone know where i could get another one?

[xr504]

Ok I finally got the plugs, gapped them and put them in. It does seem to run better but still not as good as it should. I checked the cas timing and its good. i still have not found boost leaks. Is there any other timing i should check other than the cas timing?

[redline racer510]

ok thanks. ill see if i can get my hands on a timing light tomorrow. Also i forgot to mention that my O2 sensor is broke, one of the wires is broke. could that have anything to do with it? and does anyone know where i could get another one?
Yea a bad o2 sensor can cause some afr problems I would assume. It fine tunes the afr's and I believe is even more critical under boost conditions so that might be the culprit. Sileighty 85 can you chime in on this?

[xr504]

ok. i went to autozone today to look for a o2 sensor, I have read to use a 90-95 z32 one. Should i use a TT or a NA?

[Sileighty_85]

O2 sensors are only used at idle, above 1500 RPM's the ECU ignores the O2 sensor.

According to FAST the RB25 O2 sensor is engine speciffic, so the 300ZX one wont work

Give Russell at NissanParts.cc a call and have him order one of these O2 Sensor for you if you need one

Series 1 22690-83T10
Series 2 22690-83T11

[Boostin240sx]

O2 sensors are only used at idle, above 1500 RPM's the ECU ignores the O2 sensor.

According to FAST the RB25 O2 sensor is engine speciffic, so the 300ZX one wont work

Give Russell at NissanParts.cc a call and have him order one of these O2 Sensor for you if you need one

Series 1 22690-83T10
Series 2 22690-83T11

Or buy a wideband and use the narrowband output for the ECU. A wideband could also potentially idenitfy the real problem anyway.

[95s14rb25]

what did the old plugs look like?

[redline racer510]

Or buy a wideband and use the narrowband output for the ECU. A wideband could also potentially idenitfy the real problem anyway.
I second that option

[mentordrift]

I was having these exact same problems, and I only kind if read the whole thread(so if you solved it, score!)

the fix that I needed when it would feel "jumpy" at higher rpm, like someone was flicking a light switch, turning boost on and off?
Replace your MAF.
The problem went away immediately, and this was two years ago for me. I checked all my timing, etc.
Plugs are at 0.8mm (0.022")

[xr504]

thanks for the replies, sorry about the late response.

The old plugs didnt look bad at all. they were gapped right as well.

With the O2 from Nissanparts.cc does anyone know around what they cost? lost my job so cash is real tight for the time being.

I found out my wiring for my maf had got melted together so i re wired it and then it wouldnt start. once i checked the ground wire on the maf i realized it wasnt grounded properly so i just ran a ground from that wire straight to the engine bay. It ran great peaking around 13-15 psi for 2 days then all the sudden i went to take it for a drive the third day and once it went over 7 psi it would cut in and out like you are saying. Do you think my maf went bad or something else? also my plugs are at 0.8mm.
Thanks again

[xr504]

Also i have replaced the temp guage with its own sender and its running at 180 so that seems to be good. im running out of things to do, if i had the money i would just take it to the shop but i do not so its just been sitting at my house teasing me

[vas570sx]

^i would say that there is still an issue with your maf wiring..

[Yellow4g63]

Have you check the ecu for codes yet? could be a bad coolant temp sensor or knock sensors or CAS.

[xr504]

no havent checked the ecu codes. will do that today. I just rewired the maf but ill go over it again and look for any messed up areas. it throws me off tho cuz it ran great for two days after i fixed the ground issue and now it runs like shit again

[vas570sx]

no havent checked the ecu codes. will do that today. I just rewired the maf but ill go over it again and look for any messed up areas. it throws me off tho cuz it ran great for two days after i fixed the ground issue and now it runs like shit again

thats exactly why i say to check your maf wiring again.

if you fixed it, and it ran great, but now its doing the same thing again, then its most likely the same problem.

[xr504]

I just checked the maf and wiring and it seems to be working correctly. how much volts is there supposed to be going threw it? Its getting 12v to the black and white wire and around 1v at idle on the blue and orange wire and jumps about to 3v when i rev it.

Sorry if this is a stupid question but how do i check for ecu codes? I googled it and one post said to turn the potentiometer on the ecu fully clockwise for 2 seconds then back fully counterclockwise and a LED on the ECU will flash. when i went to look for this i could not find a LED or a potentiometer. Any tips on where it is?
thanks

[Yellow4g63]

My friends RB25 had a problem like yours, He got beat by my friends NA GSR from a roll on the freeway lol. Turns out his CAS was messed up and his Knock sensor harness wasn't plugged in.

[mentordrift]

I will almost 100% garauntee that the sensor element inside your maf housing is on it's way out. The wiring might have something to do with it, but I was having literally the same problems. If I could, I'd bring my maf to you and show you lol.
If you search for posts by "MentorS14" on Nico, you can see my posts on this very topic.

[mentordrift]

Also, Bosch pn# 0258005726D09 is the usdm o2 sensor I've been using since 2009 - it's a 300zx non-turbo part unit (90-96 model year)

[xr504]

thanks, ill check out that post. Theres a couple people around here that have the same setup so hopefully i can get ahold of one of them and swap out the maf to see if thats my problem before i buy one. ill let you guys know if i figure out if that it or not

[xr504]

mentordrift is there any way you could paste the link because i couldnt find it

[supersayianjim]

old thread, any updates from these people??

[uhhh-s13 again]

What he said