S15 Boost Spike

[s15specraero]

ok...so heres the story...i just got my s15 back and i went to get it tuned with my new Apexi Afc neo...we were doing 1.25 bar with a blitz dual sbc spec r controller when we strapped it on the dyno and all is well.... he does the first pass got a well placed 270whp....im happy...well he hops out...says felt like some kind of fuel cut cause youre leaning out bad at around 5500...well he adjusts fuel and it doesnt do a damn thing...the only way we could get it to tune was to back boost down...to frikkin 220whp....like .7 bar...well my dyno chart shows boost spike...it goes up....then down...then back up...he says its either the internal wastegate or the boost controller...the car is completely stock minus a front mount...whats going on?

[jsuh s14]

what size injectors do you have.. fuel pump?

[bntmoore]

my friend had the same prob with his 240, i didnt get any specifics from him really but he said his fuel pump would pulse and it would cause his car to cut in and out in the higher rpms and then it just wouldnt go up at all. but i dont know a whole lot about 240s yet, im a fng.

[s15specraero]

its an s15...like...the whole car...so whatever the stock s15 fuel pump and inj. are...buts its not a fuel prob...the boost is spiking too fast for the fuel to keep up...you can see it in the dyno chart and af chart too

[xpertsnowcarver]

but that could still be ur prob bro... stock pump and injectors? ur doing 1.25 bar??? yea... going to need to upgrade the injectors... thats at least 20psi.... if u want to stick with 270whp then 555cc injectors are for u...

[s15specraero]

but that could still be ur prob bro... stock pump and injectors? ur doing 1.25 bar??? yea... going to need to upgrade the injectors... thats at least 20psi.... if u want to stick with 270whp then 555cc injectors are for u...


1.25 bar is like 18 psi...but thats not the prob....cause it still tries to lean out now at lower boost...just we have the spot where it leans out below 14:1...its not fuel

[Chrischeezer]

does the s15 ECU have a boost cut?

[s15specraero]

does the s15 ECU have a boost cut?

no....itll boost all i want..it just spikes up goes down then back up

[kuramaya]

Holy shit 1.25 bar with stock Turbo/MAFS/Injectors? Umm yeah thats the problem. You running a wideband while on the dyno? If not the dyno guy is an idiot. You are maxing out the MAFS at that much Boost and your injectors are pegged at 100%. I gurantee it.

edit forgot to answer your question. Boost spike = your controller or solenoid. Bypass the solenoid for the controller and run stock. See if you still spike.

[s15specraero]

Holy shit 1.25 bar with stock Turbo/MAFS/Injectors? Umm yeah thats the problem. You running a wideband while on the dyno? If not the dyno guy is an idiot. You are maxing out the MAFS at that much Boost and your injectors are pegged at 100%. I gurantee it.

edit forgot to answer your question. Boost spike = your controller or solenoid. Bypass the solenoid for the controller and run stock. See if you still spike.

yes it still spikes... no offense guys...but how many times do i have to say this is not a fuel issue...it leans out no matter where i have the boost...even at stock

[s15specraero]

go to heavythrottle.com and go to sr engine faqs then to s15...300rwhp is achievable

[McRussellPants]

The consensus is that S15 Injectors will max around 300whp.

The Maf Maxes around 260-270

The GT2560 will run to 1.25 Bar.

The setup should be fine other than the MAF maxing out.

[s15specraero]

The consensus is that S15 Injectors will max around 300whp.

The Maf Maxes around 260-270

The GT2560 will run to 1.25 Bar.

The setup should be fine other than the MAF maxing out.

ok thanks...thats what i keep trying to tell everyone..my injectors are fine...this is not a fuel issue

[McRussellPants]

but it does sound like you MAF is maxing.


Get a PowerFC and run a Z32/RB MAF on it.

more airflow over 270whp isn't registering and its limiting it.

[s15specraero]

but it does sound like you MAF is maxing.


Get a PowerFC and run a Z32/RB MAF on it.

more airflow over 270whp isn't registering and its limiting it.

ok...i have a afc neo on it now...but this isnt just happening at 1.2 bar..its at anything above .7 bar and even at .7 it just doesnt send the af above 14:1

[kuramaya]

If you need a Z32 MAFS let me know. I have a few.

[s15specraero]

ok...so i put a z32 maf on it and a walbro 255lph...its still frikkin doing it...this time we bypassed the solenoid and it stopped...here's the dyno chart....the higher one is obviously with the boost controller...the af down at the bottom that goes really far down is the one with the solenoid bypassed...the one that spikes up is with the controller...so any ideas? oh yeah were doing right at under 1.0 bar

http://i156.photobucket.com/albums/t22/89SR240sx/AlexV.jpg

[s15specraero]

Up guys...cause i really need to figure this out

[cotbu]

What are the afc corrections from 4k-6krpm?
can you get a graph with 0 smoothing?
What is the gain on the boost controller set to? and ratio?
was this for tuning or just maxpower?
I have the spec s and lowering the gain will eliminate boost spikes.
I think you need to tune your boost controller and AFC becuase you don't reach what i consider safe a/f ratios till 6k rpm
well my dyno chart shows boost spike...it goes up....then down...then back up...he says its either the internal wastegate or the boost controller...
yeah if the warning feature is set it will lower the ratio till boost is safe then if boost reaches that warning again it will lower it again and again. TUNER Problem!

[GabeS14]

If your Boost controller is not installed or setup correctly it could cause boost spike, , had this happen with my Greddy boost cntrller, when in high 4th and 5th gears, it would spike for about 1-2 seconds and then back to normal.
in case your wondering...
(stock T28)greddy boost contrller, 850cc inj, and JWT tune.
check the vac lines for the boost controller, and good luck!

[Omarius Maximus]

Have you checked for vaccum leaks?

[s15specraero]

yes the controller is hooked up correctly and as far as the afc they are as far as they will go up between 4-6k without hitting fuel cut...before that only like +5 and at 4000 and 5000 +18 then at like 6000 and 7000we actually have to take fuel away...but then when we bypassed the solenoid it went rich as crap right where we added fuel...gain is set at 10...and i looked up in the blitz manual and it said 20 for srs...so i lowered it thinking it was too high and maybe thats the problem...but no...weve had it at 0 and it still does it...and i dont think its a spike problem now...i think maybe the solenoids just wearing out....thanks a lot guys i need all the help i can get

[mayco_86]

Your best bet is to go with an external wastegate. But check you boost control it might be that your selenoid is not working properly.

[s15specraero]

Your best bet is to go with an external wastegate. But check you boost control it might be that your selenoid is not working properly.

well the turbo is factory so thats not really an option...someone said that what i might be able to do is put a manual controller on it temporarily just to see if it is the controller...that sound logical to anyone?

[slider2828]

No don't put a manual boost controller on that. They will spike for sure and asking o blow something. My friend has a blitz and I don't like it very much, but work with what you got. The curve you got there is pretty much normal and it doesn't look like its spiking, its just turbo drop off because you are pushing the turbo to the limits. Even though its an S15 man, its still a lowly T28. Secondly, why would you do a dyno pull at 18 PSI? That is retarded, because you work up to 18PSI not backwards, especially when you have unknown problems, basically you are asking to blow something.

18PSI firstly is way beyond a T28BB's efficiency, so you might as well do a search. So pulling at 1 bar how you expect to get 300HP without support mods? Like CAMs, FMIC, FPR's, etc etc? Your car isn't new and most numbers that people quote are just people's quotes, doesn't mean squat in real life.

So with 12 posts, search a little more and learn about the turbo before you start pulling with a tuner that doesn't know much about tuning. With all that said, ok you got a MAFS now and an upgrade Fuel Pump. You might want to invest in an FPR while you are at, cause stock FPRs just aren't that great. Secondly, your car is not spiking because the curve is relatively smooth, although its hard to tell since your smoothing is set to 5. Also, you probably are doing multiple pulls in succession, so you might have heat soaked your SMIC, so do you have a HUGE fan blowing on your car? If so, spray some water into your intercooler and that might help.

Secondly a dyno is supposed to tune your car and you car is stock, so don't expect it to be a dyno queen cause it ain't. Thirdly, humidity, air quality, dyno errors, can always explain the differences in HP. That is if you trust your builder. Do a full tune up and try again. 300HP is in super optimal conditions.

[s15specraero]

No don't put a manual boost controller on that. They will spike for sure and asking o blow something. My friend has a blitz and I don't like it very much, but work with what you got. The curve you got there is pretty much normal and it doesn't look like its spiking, its just turbo drop off because you are pushing the turbo to the limits. Even though its an S15 man, its still a lowly T28. Secondly, why would you do a dyno pull at 18 PSI? That is retarded, because you work up to 18PSI not backwards, especially when you have unknown problems, basically you are asking to blow something.

18PSI firstly is way beyond a T28BB's efficiency, so you might as well do a search. So pulling at 1 bar how you expect to get 300HP without support mods? Like CAMs, FMIC, FPR's, etc etc? Your car isn't new and most numbers that people quote are just people's quotes, doesn't mean squat in real life.

So with 12 posts, search a little more and learn about the turbo before you start pulling with a tuner that doesn't know much about tuning. With all that said, ok you got a MAFS now and an upgrade Fuel Pump. You might want to invest in an FPR while you are at, cause stock FPRs just aren't that great. Secondly, your car is not spiking because the curve is relatively smooth, although its hard to tell since your smoothing is set to 5. Also, you probably are doing multiple pulls in succession, so you might have heat soaked your SMIC, so do you have a HUGE fan blowing on your car? If so, spray some water into your intercooler and that might help.

Secondly a dyno is supposed to tune your car and you car is stock, so don't expect it to be a dyno queen cause it ain't. Thirdly, humidity, air quality, dyno errors, can always explain the differences in HP. That is if you trust your builder. Do a full tune up and try again. 300HP is in super optimal conditions.


ok...if you had done your research then you would notice that im not trying for a dyno queen just 270....and that im not doing 18....im doin right under 1.0 bar...i was doing 1.2 which is like 17....now im doing 14...and you dont even know the guy so you dont know that he cant tune...and if you would read a little further...i said i didnt think it was spiking now...just that the solenoid may be wearing out...and its obviously not normal if it stopped when we unhooked the solenoid...if i were to turn the controller off and still run it through the solenoid it would still cause my problem....so obviously its something with that...and yes i do have a fmic ....and finally dont be a [email protected]@ about it....you have no room to tell me to do research when you obviously didnt read further to get your facts right...what it sounds like to me is that your just pissed cause youre stuck with that lil pignose...

[s15specraero]

Is this front mount big enough for you SLIDER2828???

http://i156.photobucket.com/albums/t22/89SR240sx/0928070947.jpg

[slider2828]

Sure but running pulls is going to soak that too. But the T28 doesn't run to 18psi and still have efficiency.