S14 SR20 problems under boost - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ApexRK · 05-08-2007, 10:07 AM

Car is a 97 Kouki with a zenki S14 SR20, only mods are walbro pump, fmic and turboback exhaust.
When getting into the boost the car almost bucks a bit and feels very irractic on power, once its at full boost 8-10psi I am getting what feels like the timing being pulled and then advancing giving that on/off feeling. Then sometimes it just doesn't want to go under WOT just bogs on the power.
I did have a big boost leak, but its fixed and still the problem is there. I don't have any logging software to monitor anything so I'm at a loss as to what it could be, any ideas?

Yes I did search, but nothing answered by question.

wookieballa · 05-08-2007, 10:12 AM

try the starter fluid trick, spraying it on your piping connections, you may still have a boost leak, check into the starter fluid first, as it may damage your piping finish, not sure. does it have the correct mafs? and is it in safe mode does it idle ok? i would assume its a boost leak somewhere.

chrisman2k · 05-08-2007, 10:25 AM

I have the exact same problem on my 98 with a rb25 in it. With me though, anything over 8-9psi, it starts pulling timing also. My solution, put better gas in it. I was told by a couple of people that since I have a stock setup out of japan, our 91 oct. gas is not enough. They said that over in japan, premium gas is 100 oct.

so I tried putting some in and wala, no more issues.

I also asked about several friends I have that have stock SR setups that are boosting way more, and they said that for the s13 sr20's they have a smaller turbo and that they don't flow as much as the later sr's and rb25's.

Hope this helps

If anybody knows different, or if the people I talked to were wrong, please correct me!

EDIT: I don't have boost leaks, already checked and corrected

ApexRK · 05-08-2007, 11:22 AM

It is using the stock SR maf so that is not the problem, plus normal driving is just fine, cruising, light/moderate acceleration is great, smooth idle so I doubt anythign to do with a MAF. This has boost leak written all over it, but there are no leaks last I checked.

I am running 94oct so gas is also not an issue.

Unless someone has anything I else to suggest I'm going to try another boost leak test to make sure another one hasn't started.

wookieballa · 05-08-2007, 11:30 AM

check your BOV is it blowing by a little, also check your exhaust mani, it may be loose, causing issues, and your maf may be bad, grab a SOHC maf from the junk yard, and try that, could be just having issues with that. good luck. (sorry to repost, but i just thought of these issues)

ApexRK · 05-08-2007, 12:05 PM

Quote:

Originally Posted by wookieballa

check your BOV is it blowing by a little, also check your exhaust mani, it may be loose, causing issues, and your maf may be bad, grab a SOHC maf from the junk yard, and try that, could be just having issues with that. good luck. (sorry to repost, but i just thought of these issues)

BOV is good no leaks at all.
exhaust mani, no leaks cause if there was I would know by now.
MAF could be it so I'll see if I can get my hands on a spare one. Tell me does a KA maf work on a SR, harness snaps on too? I honestly don't know.

Z U L8R · 05-08-2007, 01:04 PM

s14 ka is different, there are 2 kinds of s13', both will work if you have the pig tails, there's the 4 pin plug that's really a 3 pin plug, then there's the 3 pin plug that doesn't have the naked extra pin. gl

mr_240sx · 05-08-2007, 01:22 PM

Ryan, if you want i can bring my s14 sr maf with me when i come over tonight and we can test out to see if the problem is maf related. let me know if you want me to do that.

Mats

wookieballa · 05-08-2007, 01:37 PM

my bad, i didnt see that it was an s14 sr, you can use the sohc mafs (ka) for the s13 sr's, but not the s14. they are different. so you will need an s14 sr mafs to try, and if thats bad, you may have to just go with a z32 mafs, and SAFC or some other piggy back type air/fuel computer to adjust for the mafs change.

ApexRK · 05-08-2007, 01:39 PM

Quote:

Originally Posted by mr_240sx

Ryan, if you want i can bring my s14 sr maf with me when i come over tonight and we can test out to see if the problem is maf related. let me know if you want me to do that.

Mats

Shit I didn't even think to ask you Mats, ya definetly bring it with you that will be a huge help.

ApexRK · 05-08-2007, 06:16 PM

So it seems I have solved the problem, but not without some question. A very knowledgable friend of mine suggested playing with the CAS which I did. I already had the timing set at 15degrees as per the FSM procedure, but the CAS was fully to one end of the adjustment range to get there, full retarded. So I moved it more in the middle, drove around and the car was ALIVE!, came back home to check the timing with the light and after adjusting it again I ended up having the CAS set where the car ran great, but it was at 24degree base timing?

Why is that? in order to get the car to run normal and have the CAS positioned in the middle the timing is 24degrees?? can someone help me on that? I know 15degrees is the factory spec and its just a suggestion, but 24 is far off that.

mr_240sx · 05-08-2007, 10:23 PM

tks for all the help tonight Ryan..... good to see your sr running good!

ApexRK · 05-09-2007, 07:27 AM

no problem mats

started a new thread on the timing issue since its a new problem now http://www.zilvia.net/f/showthread.p...92#post1368092

05-08-2007, 10:07 AM	#1
ApexRK Leaky Injector Join Date: Feb 2007 Location: Kingston, ont Age: 44 Posts: 79 Trader Rating: (0) Feedback Score: 0 reviews	S14 SR20 problems under boost Car is a 97 Kouki with a zenki S14 SR20, only mods are walbro pump, fmic and turboback exhaust. When getting into the boost the car almost bucks a bit and feels very irractic on power, once its at full boost 8-10psi I am getting what feels like the timing being pulled and then advancing giving that on/off feeling. Then sometimes it just doesn't want to go under WOT just bogs on the power. I did have a big boost leak, but its fixed and still the problem is there. I don't have any logging software to monitor anything so I'm at a loss as to what it could be, any ideas? Yes I did search, but nothing answered by question.

05-08-2007, 10:25 AM	#3
chrisman2k Leaky Injector Join Date: Jan 2007 Location: PHX Age: 43 Posts: 132 Trader Rating: (0) Feedback Score: 0 reviews	I have the exact same problem on my 98 with a rb25 in it. With me though, anything over 8-9psi, it starts pulling timing also. My solution, put better gas in it. I was told by a couple of people that since I have a stock setup out of japan, our 91 oct. gas is not enough. They said that over in japan, premium gas is 100 oct. so I tried putting some in and wala, no more issues. I also asked about several friends I have that have stock SR setups that are boosting way more, and they said that for the s13 sr20's they have a smaller turbo and that they don't flow as much as the later sr's and rb25's. Hope this helps If anybody knows different, or if the people I talked to were wrong, please correct me! EDIT: I don't have boost leaks, already checked and corrected __________________ Last edited by chrisman2k; 05-08-2007 at 10:27 AM.. Reason: added info

05-08-2007, 10:12 AM	#2
wookieballa Leaky Injector Join Date: Jan 2007 Location: Arizona Age: 50 Posts: 123 Trader Rating: (3) Feedback Score: 3 reviews	try the starter fluid trick, spraying it on your piping connections, you may still have a boost leak, check into the starter fluid first, as it may damage your piping finish, not sure. does it have the correct mafs? and is it in safe mode does it idle ok? i would assume its a boost leak somewhere.

05-08-2007, 11:22 AM	#4
ApexRK Leaky Injector Join Date: Feb 2007 Location: Kingston, ont Age: 44 Posts: 79 Trader Rating: (0) Feedback Score: 0 reviews	It is using the stock SR maf so that is not the problem, plus normal driving is just fine, cruising, light/moderate acceleration is great, smooth idle so I doubt anythign to do with a MAF. This has boost leak written all over it, but there are no leaks last I checked. I am running 94oct so gas is also not an issue. Unless someone has anything I else to suggest I'm going to try another boost leak test to make sure another one hasn't started.

05-08-2007, 11:30 AM	#5
wookieballa Leaky Injector Join Date: Jan 2007 Location: Arizona Age: 50 Posts: 123 Trader Rating: (3) Feedback Score: 3 reviews	check your BOV is it blowing by a little, also check your exhaust mani, it may be loose, causing issues, and your maf may be bad, grab a SOHC maf from the junk yard, and try that, could be just having issues with that. good luck. (sorry to repost, but i just thought of these issues)

05-08-2007, 01:04 PM	#7
Z U L8R Zilvia FREAK! Join Date: Jan 2007 Location: Georgia Age: 43 Posts: 1,194 Trader Rating: (0) Feedback Score: 0 reviews	s14 ka is different, there are 2 kinds of s13', both will work if you have the pig tails, there's the 4 pin plug that's really a 3 pin plug, then there's the 3 pin plug that doesn't have the naked extra pin. gl

05-08-2007, 01:22 PM	#8
mr_240sx Post Whore! Join Date: Nov 2004 Location: Ottawa Age: 38 Posts: 6,320 Trader Rating: (4) Rides Gallery: mr_240sx Feedback Score: 4 reviews	Ryan, if you want i can bring my s14 sr maf with me when i come over tonight and we can test out to see if the problem is maf related. let me know if you want me to do that. Mats

05-08-2007, 01:37 PM	#9
wookieballa Leaky Injector Join Date: Jan 2007 Location: Arizona Age: 50 Posts: 123 Trader Rating: (3) Feedback Score: 3 reviews	my bad, i didnt see that it was an s14 sr, you can use the sohc mafs (ka) for the s13 sr's, but not the s14. they are different. so you will need an s14 sr mafs to try, and if thats bad, you may have to just go with a z32 mafs, and SAFC or some other piggy back type air/fuel computer to adjust for the mafs change.

05-08-2007, 06:16 PM	#11
ApexRK Leaky Injector Join Date: Feb 2007 Location: Kingston, ont Age: 44 Posts: 79 Trader Rating: (0) Feedback Score: 0 reviews	So it seems I have solved the problem, but not without some question. A very knowledgable friend of mine suggested playing with the CAS which I did. I already had the timing set at 15degrees as per the FSM procedure, but the CAS was fully to one end of the adjustment range to get there, full retarded. So I moved it more in the middle, drove around and the car was ALIVE!, came back home to check the timing with the light and after adjusting it again I ended up having the CAS set where the car ran great, but it was at 24degree base timing? Why is that? in order to get the car to run normal and have the CAS positioned in the middle the timing is 24degrees?? can someone help me on that? I know 15degrees is the factory spec and its just a suggestion, but 24 is far off that.

05-08-2007, 10:23 PM	#12
mr_240sx Post Whore! Join Date: Nov 2004 Location: Ottawa Age: 38 Posts: 6,320 Trader Rating: (4) Rides Gallery: mr_240sx Feedback Score: 4 reviews	tks for all the help tonight Ryan..... good to see your sr running good!

05-09-2007, 07:27 AM	#13
ApexRK Leaky Injector Join Date: Feb 2007 Location: Kingston, ont Age: 44 Posts: 79 Trader Rating: (0) Feedback Score: 0 reviews	no problem mats started a new thread on the timing issue since its a new problem now http://www.zilvia.net/f/showthread.p...92#post1368092