rb25 maf problem.? car is cutting out randomly - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

b00stinbmx · 04-11-2011, 01:30 PM

ok so heres the issue, try to make this as short and detailed as possible.
rb25det s2
z32 maf
nistune on z32 ecu

car has been running pretty good for the last 3 weeks or so. still working out the little problems and it seems as im getting close but this one is really bothering me, esp since it dosen;t happen every day. now im getting a little scared to drive it anywhere though.

basically when crusing or comming to a stop the car is dieing every few times. to be more specific ill be cruising on the highway doing 75mph or so. 1/8th-1/4 throttle steady, blah car cuts out completely, ususally have to pump the gas 1 or 2 times and it fires right back up and goes fine. sometimes comming to stop and stop signs the car dies or wants to and it either shows full lean or 10.0 on the wideband. so anyway i plugged in nistune as soon as this happened and i always get 3 codes. 1 fuel temp sensor (normal since its z32 ecu on rb25) AFM code, and speed sensor. not sure where the speed sensor is comming from but yes it looks like im getting a code for my maf. so i checked the wiring, i actually moved the 12v ground which was on the wire harness tied into that terminal that gets grounded to the intake and i moved it to its own chasis ground seperate from eveyrthing. that didn't help one bit. now im just pretty much stuck. i can't see if being a bad maf becuase somedays after driving the car 100 miles it dosen;t do it and runs fine, then other days im scared to drive it 5. im really stumped here but i need some suggestions. i tried datalonging in nistune one day to see if i could find anything but of course that day the car decided to run perfect. but help me out guys im on a mission to get this solved so i can make it to a new england 240 meet this weekend and hopefully start hitting some drift evetns soon but i don;t quite trust the car yet.

Sileighty_85 · 04-11-2011, 04:08 PM

lol I kinda have the same issue.

Mine will do that for 1-2 seconds, It got really bad yesterday and checked the codes right when it happend and I got the MAFS code and the A/T signal )even though its a M/T ECU.

Im getting another J60 MAFS to see if that will fix my issue though

Mi BEAN · 04-22-2011, 03:04 PM

This is the same problem i am having!! on top of others of course. found out today that my tps is bad. check that. if i figure it out ill post.

xr504 · 09-19-2011, 10:15 AM

I am having a similar issue as well. starts up fine and drives great for a few minutes then just dies randomly, after it sits for a few minutes it starts right back up. I was thinking my fuel pump was freezing up after it got warmed up but i hooked up a fuel pressure guage and it still has great pressure wen it dies out. If any of you found the problem on your cars it would help me with mine alot.

Sileighty_85 · 09-19-2011, 10:57 AM

Mine ended up being the MAFS, I replaced mine with another one and havent had any issues since

xr504 · 09-19-2011, 02:50 PM

ok. could it be due to me rewiring the maf and not using the correct type of wires? i read that somewhere but cant remember where

godzillarb · 09-20-2011, 08:35 AM

The wires should be shielded to the maf, if that's what you mean.

I've heard of a lot of guys having strange running problems with the nistune. Anyway, get a new maf and tps. They're good to have as spares anyways.

xr504 · 09-21-2011, 09:49 AM

yea thats what i mean. sorry for the confusion. But could that be causing this problem?

godzillarb · 09-21-2011, 10:40 AM

I'm not a wiring specialist, but apparently the most important place for them to be shielded is coming out of the bundle of wires where the ecu is. Something about there being the biggest chance for interference. However, on my rb25 the dipshit who originally did the swap didn't shield the MAF wiring in the engine bay like it's supposed to be, but I don't have the problems you're describing. It's possible that there's a short somewhere / ripped wire / other electrical problem, but the most likely culprit is a bad TPS or MAF. My RB26 car had weird issues (running super lean or rich) and it was a faulty TPS.

xr504 · 09-21-2011, 10:47 AM

ok thanks alot, im assuming the wiring is not shielded because the guy i got this motor from rigged everything, even had the front mount and bumper zip tied on (hanging about 2 inches from the ground). guess ill be investing in a new maf and see if that fixes it

godzillarb · 09-21-2011, 10:54 AM

Get yourself a service manual. They're floating around on the web somewhere, just can't remember where atm.

There's a way to check the TPS with a volt meter to see if it's bad or not. IIRC, closed voltage should be .40-.60ish and should slowly clime once it's opened. But yeah, get a MAF and download a service manual. Probably wouldn't hurt to have a look at your harness, there might be some wires touching that shouldn't be.

04-11-2011, 01:30 PM	#1
b00stinbmx Zilvia Member Join Date: Oct 2008 Location: Lebanon, CT Age: 35 Posts: 214 Trader Rating: (5) Feedback Score: 5 reviews	rb25 maf problem.? car is cutting out randomly ok so heres the issue, try to make this as short and detailed as possible. rb25det s2 z32 maf nistune on z32 ecu car has been running pretty good for the last 3 weeks or so. still working out the little problems and it seems as im getting close but this one is really bothering me, esp since it dosen;t happen every day. now im getting a little scared to drive it anywhere though. basically when crusing or comming to a stop the car is dieing every few times. to be more specific ill be cruising on the highway doing 75mph or so. 1/8th-1/4 throttle steady, blah car cuts out completely, ususally have to pump the gas 1 or 2 times and it fires right back up and goes fine. sometimes comming to stop and stop signs the car dies or wants to and it either shows full lean or 10.0 on the wideband. so anyway i plugged in nistune as soon as this happened and i always get 3 codes. 1 fuel temp sensor (normal since its z32 ecu on rb25) AFM code, and speed sensor. not sure where the speed sensor is comming from but yes it looks like im getting a code for my maf. so i checked the wiring, i actually moved the 12v ground which was on the wire harness tied into that terminal that gets grounded to the intake and i moved it to its own chasis ground seperate from eveyrthing. that didn't help one bit. now im just pretty much stuck. i can't see if being a bad maf becuase somedays after driving the car 100 miles it dosen;t do it and runs fine, then other days im scared to drive it 5. im really stumped here but i need some suggestions. i tried datalonging in nistune one day to see if i could find anything but of course that day the car decided to run perfect. but help me out guys im on a mission to get this solved so i can make it to a new england 240 meet this weekend and hopefully start hitting some drift evetns soon but i don;t quite trust the car yet.

04-11-2011, 04:08 PM	#2
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	lol I kinda have the same issue. Mine will do that for 1-2 seconds, It got really bad yesterday and checked the codes right when it happend and I got the MAFS code and the A/T signal )even though its a M/T ECU. Im getting another J60 MAFS to see if that will fix my issue though __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

09-19-2011, 10:57 AM	#5
Sileighty_85 Post Whore! Join Date: Dec 2006 Location: Misawa, Japan Posts: 6,815 Trader Rating: (8) Feedback Score: 8 reviews	Mine ended up being the MAFS, I replaced mine with another one and havent had any issues since __________________ 後輪駆動車１番 1989 Built SR GT2871R -363whp 1998 S14 W/RB25- 250ish (For Now) 1986 SR86 - 200ish 1990 R32 GTR - 320hp Don't Buy Engines from JDM-Online http://zilvia.net/f/businesses/207457-jdm-online.html Don't Buy XS-Power or SSAC Shit

09-20-2011, 08:35 AM	#7
godzillarb Zilvia Junkie Join Date: Jun 2005 Location: Destin, FL Age: 35 Posts: 487 Trader Rating: (0) Feedback Score: 0 reviews	The wires should be shielded to the maf, if that's what you mean. I've heard of a lot of guys having strange running problems with the nistune. Anyway, get a new maf and tps. They're good to have as spares anyways. __________________ INTENSE POWER RIPPED ME OFF

09-21-2011, 10:40 AM	#9
godzillarb Zilvia Junkie Join Date: Jun 2005 Location: Destin, FL Age: 35 Posts: 487 Trader Rating: (0) Feedback Score: 0 reviews	I'm not a wiring specialist, but apparently the most important place for them to be shielded is coming out of the bundle of wires where the ecu is. Something about there being the biggest chance for interference. However, on my rb25 the dipshit who originally did the swap didn't shield the MAF wiring in the engine bay like it's supposed to be, but I don't have the problems you're describing. It's possible that there's a short somewhere / ripped wire / other electrical problem, but the most likely culprit is a bad TPS or MAF. My RB26 car had weird issues (running super lean or rich) and it was a faulty TPS. __________________ INTENSE POWER RIPPED ME OFF

04-22-2011, 03:04 PM	#3
Mi BEAN Leaky Injector Join Date: Mar 2011 Location: Norfolk, Va Age: 35 Posts: 94 Trader Rating: (0) Feedback Score: 0 reviews	This is the same problem i am having!! on top of others of course. found out today that my tps is bad. check that. if i figure it out ill post.

09-19-2011, 10:15 AM	#4
xr504 Join Date: Feb 2011 Location: Cincinnati Age: 30 Posts: 46 Trader Rating: (0) Feedback Score: 0 reviews	I am having a similar issue as well. starts up fine and drives great for a few minutes then just dies randomly, after it sits for a few minutes it starts right back up. I was thinking my fuel pump was freezing up after it got warmed up but i hooked up a fuel pressure guage and it still has great pressure wen it dies out. If any of you found the problem on your cars it would help me with mine alot.

09-19-2011, 02:50 PM	#6
xr504 Join Date: Feb 2011 Location: Cincinnati Age: 30 Posts: 46 Trader Rating: (0) Feedback Score: 0 reviews	ok. could it be due to me rewiring the maf and not using the correct type of wires? i read that somewhere but cant remember where

09-21-2011, 09:49 AM	#8
xr504 Join Date: Feb 2011 Location: Cincinnati Age: 30 Posts: 46 Trader Rating: (0) Feedback Score: 0 reviews	yea thats what i mean. sorry for the confusion. But could that be causing this problem?

09-21-2011, 10:47 AM	#10
xr504 Join Date: Feb 2011 Location: Cincinnati Age: 30 Posts: 46 Trader Rating: (0) Feedback Score: 0 reviews	ok thanks alot, im assuming the wiring is not shielded because the guy i got this motor from rigged everything, even had the front mount and bumper zip tied on (hanging about 2 inches from the ground). guess ill be investing in a new maf and see if that fixes it

09-21-2011, 10:54 AM	#11
godzillarb Zilvia Junkie Join Date: Jun 2005 Location: Destin, FL Age: 35 Posts: 487 Trader Rating: (0) Feedback Score: 0 reviews	Get yourself a service manual. They're floating around on the web somewhere, just can't remember where atm. There's a way to check the TPS with a volt meter to see if it's bad or not. IIRC, closed voltage should be .40-.60ish and should slowly clime once it's opened. But yeah, get a MAF and download a service manual. Probably wouldn't hurt to have a look at your harness, there might be some wires touching that shouldn't be. __________________ INTENSE POWER RIPPED ME OFF

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode