My notch top sr wont rev passed 2k!! help! - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

s14j · 01-16-2014, 06:37 PM

okay guys need some help here im completely stumped on my sr. i posted on the small question but hardly got any responces.

this is a zenki notch top wc ecu and )both f00-f01 mafs have been used)
my cars been great after the rebuild until last week.

my idle is fine but the car cuts up under revving. cold it will rev but miss fire and backfire up around the 5-6krpm.
complete operating temp at W.O.T. is will revv to 2k-2500k and bounce there like if it has a limiter.

i have changed mafs and same problem. both maf test good resistance of 5 ohms i believe that is correct. iv check wiring as well but it is a new harness from wiring specialties and the car was running prior.

TPS has been changed to a new one

my CTS has been borrowed from my brothers red top which was working and still the issue is there (also the o2 sensor has been chnaged same thing)

all boost leaks and piping as sealed. its a stock s14smic

i checked spark and its there i haven't checked resistance on my CAS because i really cant find info on it. haven't checked my knock sensor.

im assuming with the 2k revv limit that the ecu is in limp mode? i cant seem to figure out whats going on i feel like giving up the cars been having so many issues here hand there i just want it running again. any one delt with something close to this problem?

please fellow Zilvia members help me out!

rotation3x · 01-16-2014, 08:01 PM

Check the knock sensor. You can put in a 1k ohm resistor to bypass it to see if that is the problem.

Also check wiring voltage at the mafs per fsm.

*brndck* · 01-16-2014, 08:17 PM

It doesn't sound like your maf is wired correctly. Get a FSM and start from there.

Renelovesnike · 01-16-2014, 08:41 PM

did ya make sure the Fuel Filters not installed backwards? something small i know but its always good to double check*

s14j · 01-16-2014, 08:57 PM

Quote:

Originally Posted by rotation3x

Check the knock sensor. You can put in a 1k ohm resistor to bypass it to see if that is the problem.

Also check wiring voltage at the mafs per fsm.

Quote:

Originally Posted by brndck

It doesn't sound like your maf is wired correctly. Get a FSM and start from there.

Quote:

Originally Posted by Renelovesnike

did ya make sure the Fuel Filters not installed backwards? something small i know but its always good to double check*

i haven't tried that. the knock sensor was new oem when i installed the motor last year in nov. i will check the resistance thou tomorrow

as for the maf wiring its a wiring specialties harness with the exchangeable maf plugs so theres no way it could be switched car was running.

fuel filter hasent been moved.

i will be checking my fuel pressure tomorrow. see what happens. any other thoughts?

oni jake · 01-17-2014, 12:51 AM

From the 2k limit, I would guess your ECU went into limp mode. Have you tried pulling the codes to see what it says?

Check your knock sensor and water temp sensor. Plugs F116 and F122 (this is from the S15 FSM, sensors are in the same place.)

s14j · 01-17-2014, 06:43 PM

Quote:

Originally Posted by oni jake

From the 2k limit, I would guess your ECU went into limp mode. Have you tried pulling the codes to see what it says?

Check your knock sensor and water temp sensor. Plugs F116 and F122 (this is from the S15 FSM, sensors are in the same place.)

i checked the knock sensor and the plug and everything seems fine.
yeah im guessing its on limp mode.

dose anyone know the resistance a s14 maf should have? i only can find the voltage.

rotation3x · 01-17-2014, 07:25 PM

Is the ecu the same one you had installed before the rebuild.

I recently trouble shot the hell out my zenki sr it would not rev past 3k. Turned out I had a tuned ecu with a daughter board installed by a company in japan. I swapped the resistor from
j011 to the factory j010 location and it now revs all the way to redline.

s14j · 01-22-2014, 01:56 AM

so my buddy came a couple nights ago with his ECU talk and all we found was the knock sensor harness was bad,

fixed it same problem thou, besides that everything else was reading fine.

haven't had time to check my Fuel pump going to try to tomorrow.

*fliprayzin240sx* · 01-22-2014, 02:19 AM

You done the basics? Double checked mechanical timing to make sure its not off by a tooth, base timing set to 15* (2nd mark from the right), spark plugs gapped properly, TPS voltage correct? Checked the ECU for codes?

ultimateirving · 01-22-2014, 08:00 AM

Also are you sure the CTS is the same from s13 redtops to s14 notch tops? I thought it had to match the engine. i Could be wrong but might be worth checking.
Other things i would check, make sure the spark plugs are not cracked and possibly grounding out
Also i would boost leak test it make sure no cuts or leaks have developed around the couplers.

s14j · 01-22-2014, 07:56 PM

so after i saw my fuel pressure at 29-30 and increase

i pulled my pump and on s14 the tiny 2" hose that connects the fuel pump to the assembly has tore.

FAIL of the month. great way to start the year! atleast everything as been checked over and over! cars running great!

thank to everyone who chimed in! thanks!

01-16-2014, 06:37 PM	#1
s14j Zilvia FREAK! Join Date: Oct 2009 Location: Hollywood Age: 33 Posts: 1,087 Trader Rating: (72) Feedback Score: 72 reviews	My notch top sr wont rev passed 2k!! help! okay guys need some help here im completely stumped on my sr. i posted on the small question but hardly got any responces. this is a zenki notch top wc ecu and )both f00-f01 mafs have been used) my cars been great after the rebuild until last week. my idle is fine but the car cuts up under revving. cold it will rev but miss fire and backfire up around the 5-6krpm. complete operating temp at W.O.T. is will revv to 2k-2500k and bounce there like if it has a limiter. i have changed mafs and same problem. both maf test good resistance of 5 ohms i believe that is correct. iv check wiring as well but it is a new harness from wiring specialties and the car was running prior. TPS has been changed to a new one my CTS has been borrowed from my brothers red top which was working and still the issue is there (also the o2 sensor has been chnaged same thing) all boost leaks and piping as sealed. its a stock s14smic i checked spark and its there i haven't checked resistance on my CAS because i really cant find info on it. haven't checked my knock sensor. im assuming with the 2k revv limit that the ecu is in limp mode? i cant seem to figure out whats going on i feel like giving up the cars been having so many issues here hand there i just want it running again. any one delt with something close to this problem? please fellow Zilvia members help me out! __________________ 95 s14 ka DD

01-22-2014, 01:56 AM	#9
s14j Zilvia FREAK! Join Date: Oct 2009 Location: Hollywood Age: 33 Posts: 1,087 Trader Rating: (72) Feedback Score: 72 reviews	so my buddy came a couple nights ago with his ECU talk and all we found was the knock sensor harness was bad, fixed it same problem thou, besides that everything else was reading fine. haven't had time to check my Fuel pump going to try to tomorrow. __________________ 95 s14 ka DD

01-22-2014, 02:19 AM	#10
fliprayzin240sx Man w/ CTSV & a Car Seat Join Date: Aug 2002 Location: Tampa Posts: 17,998 Trader Rating: (19) Rides Gallery: fliprayzin240sx Feedback Score: 19 reviews	You done the basics? Double checked mechanical timing to make sure its not off by a tooth, base timing set to 15* (2nd mark from the right), spark plugs gapped properly, TPS voltage correct? Checked the ECU for codes? __________________ If you think Zilvia has too many assholes... CLICK HERE!!!

01-22-2014, 08:00 AM	#11
ultimateirving Zilvia FREAK! Join Date: Nov 2010 Location: arizona Age: 37 Posts: 1,521 Trader Rating: (1) Feedback Score: 1 reviews	Also are you sure the CTS is the same from s13 redtops to s14 notch tops? I thought it had to match the engine. i Could be wrong but might be worth checking. Other things i would check, make sure the spark plugs are not cracked and possibly grounding out Also i would boost leak test it make sure no cuts or leaks have developed around the couplers. __________________ Z32 with lq4 swap Desert Street Scene \|\| Dssevents.com

01-22-2014, 07:56 PM	#12
s14j Zilvia FREAK! Join Date: Oct 2009 Location: Hollywood Age: 33 Posts: 1,087 Trader Rating: (72) Feedback Score: 72 reviews	so after i saw my fuel pressure at 29-30 and increase i pulled my pump and on s14 the tiny 2" hose that connects the fuel pump to the assembly has tore. FAIL of the month. great way to start the year! atleast everything as been checked over and over! cars running great! thank to everyone who chimed in! thanks! __________________ 95 s14 ka DD Last edited by s14j; 01-23-2014 at 05:44 PM.. Reason: found the problem

01-16-2014, 08:01 PM	#2
rotation3x Zilvia Member Join Date: Jun 2005 Location: virginia Age: 39 Posts: 272 Trader Rating: (2) Feedback Score: 2 reviews	Check the knock sensor. You can put in a 1k ohm resistor to bypass it to see if that is the problem. Also check wiring voltage at the mafs per fsm.

01-16-2014, 08:41 PM	#4
Renelovesnike Nissanaholic! Join Date: Jun 2009 Location: (562) Posts: 1,616 Trader Rating: (30) Feedback Score: 30 reviews	did ya make sure the Fuel Filters not installed backwards? something small i know but its always good to double check*

01-17-2014, 12:51 AM	#6
oni jake Zilvia Junkie Join Date: Sep 2007 Location: ---------- Posts: 416 Trader Rating: (5) Feedback Score: 5 reviews	From the 2k limit, I would guess your ECU went into limp mode. Have you tried pulling the codes to see what it says? Check your knock sensor and water temp sensor. Plugs F116 and F122 (this is from the S15 FSM, sensors are in the same place.)

01-17-2014, 07:25 PM	#8
rotation3x Zilvia Member Join Date: Jun 2005 Location: virginia Age: 39 Posts: 272 Trader Rating: (2) Feedback Score: 2 reviews	Is the ecu the same one you had installed before the rebuild. I recently trouble shot the hell out my zenki sr it would not rev past 3k. Turned out I had a tuned ecu with a daughter board installed by a company in japan. I swapped the resistor from j011 to the factory j010 location and it now revs all the way to redline.