hits 17 psi stock

[SniperXr2]

Hey everyone, I just recently installed my boost gauge. The only other mods I have are: K&N inatke with adaptor, and Greddy Type-S BOV. Now whenever I floor it my boost shoots up to about 17 psi, hold for a second, then goes down to 15, and it stays there untill about 4500-5000 RPM then after that it goes down to 12 PSI. Does that sound normal? Also at an Idle I have about 18- 20 vac, and when slowing down I have about 20-24. Does this all sound normal or should I be worried. Thanks in advance.
-Rob

 

[92awdgsx]

that is what is called "boost spike" yes that is normal. you can get rid of that with a good boost controler. a good boost controler should get rid of or atleast improve the boost drop. and the vac sounds normal too.

 

[scottsee]

on my 96 gsx i hit full boost spike @ 17-18 psi, then it backs off to 15-16 psi. cold starts are about 18 vac 15 crusing. i have fipk, dejontool uicp, ig bov, injen pipe, boost control sylinoid mod, no boost contoller.

 

[Wanted:SWGSXAWD]

I've just started modding too, so I've got the same mods + an MBC. I let mine spike to 15# with the MBC and the it falls to 12-13#. Once I rewire my fuel pump I'll bump it to 16 and run an open down pipe maybe.

 

[SniperXr2]

At what point will I hit fuel cut? I want to do the BCS removal mod, but I dont wanna hit cut while I am driving. If I hit fuel cut does the car like turn off? Or will it just kind of kick back some? Also would a cheap home made MBC help with the spike, or should I cough up the money to get a better one? Thanks alot guys.
-Rob

 

[gsxtacy]

Fuel Cut is DAMN NEAR impossible for the T25.

I say damn near, cause in all of my 4 yrs around DSM's, I have YET to see a real Fuel Cut scenario with a T25 on the car.

14B's YES, 16G's you better believe it.

Fuel Cut really becomes a problem when you have a upgrade turbo such as a 16G, stock fuel injectors, air filter, UICP with a better BOV, and run more than 18-20 psi.

I know, I have hit REAL fuel cut before.

Stay below 17 psi on a 16g and it will only do it when it gets cool (below 50*)
Stay below 15 psi on a 16G and it will probably never happen.

T25s can't pull that much air, well I guess if you wired the wastegate closed it could.....but realistically...NO.

gsxtacy

 

[LiquidGS-T]

HA, I ran my T25 at over 20 psi just playin around. you can't hit fuel cut because around 4500 RPM you start loosing boost. The turbo can't keep up enough to hold a solid pressure, it can't hit fuel cut. On the other hand though my t-25 was on its death bed and that was its celebration beating before the 16g replaced it .

 

[olmytsi]

i have hit fuel cut on the t25 at 18 psi on really cold days.

 

[Onnipotente]

does boost spike harm the turbo in the long run?

 

[gsxtacy]

You mean you read posts here and don't want in on the modding? Your gonna stay on the stock turbo?

Who cares what a happens to a T25, they need to die so Big28's can be made.

Boost spike the crap out of it, It doesn't matter, it can't flow that amount of air anyways.

For performance, no. Set the boost controller to a boost level the turbo can maintain....like 12-14 psi.

gsxtacy

 

[Wanted:SWGSXAWD]

I had the BCS restrictor mod (no boost gauge at the time) and never even knew what people were talking about with fuel cut However, when I hooked up my MBC wrong and went to see how it would feel, I hit fuel cut bigtime after my boost gauge hit 25# in 3rd gear (so I tried it 2 more times ). God I miss that feeling, once it was hooked up correctly and topping out at 15# it felt like somebody kicked my car in the nads .

 

[DSMeclipse4G63]

Fuel Cut is DAMN NEAR impossible for the T25.

I say damn near, cause in all of my 4 yrs around DSM's, I have YET to see a real Fuel Cut scenario with a T25 on the car.

14B's YES, 16G's you better believe it.

Fuel Cut really becomes a problem when you have a upgrade turbo such as a 16G, stock fuel injectors, air filter, UICP with a better BOV, and run more than 18-20 psi.

I know, I have hit REAL fuel cut before.

Stay below 17 psi on a 16g and it will only do it when it gets cool (below 50*)
Stay below 15 psi on a 16G and it will probably never happen.

T25s can't pull that much air, well I guess if you wired the wastegate closed it could.....but realistically...NO.

gsxtacy

when I had my t25 I hit fuel cut TWO times setting my boost controller up. Yes I agree it takes ALOT for the t25 to fuel cut I had the boost gauge pegged past 20psi. On my big 16g I hit fuel cut around 5krpms to 62oorpms when/if the creep goes past 18psi(all depends on temp).
Andrew

 

[DarkStarMenace]

I have a Spyder GST with 1g BOV (crushed), FIPK, 3" DP, Hi-Flow Cat, and Magnaflow muffler. Hooked up a boost gauge and spikes @ 18, drops to 15, and holds @ 12. I disconnected the stock boost controller and now it spikes @ 14 and holds @ 12. On a side note, does anyone know if I need high impedence or low impedence injectors for a 14b swap? Extreme PSI sells high but i heard the Mitsubishi ECU reads low impedence injectors.

Thanks
Adam

 

[SniperXr2]

What exactlly happens when your car hits fuel cut? Does it turn off or what? Does the T-25 even give you boost beyond 15 or so? I didnt think It was even capable of pushing that much. Would a cheep ebay MBC work well for my boost spike or should I invest in something a little better? Sorry for any spelling/grammer mistakes, it is late and I had to have a friend drive me home. Thanks alot guys
-Rob

 

[gsxtacy]

Imagine your tearing down the quarter mile.

You've already banged the 1-2 and your in second right after the shift.....the needle is around 5000 rpm and WHAM....Who left a Sewer Cap off in the middle of the dragstrip?

It feels exactly like both your front wheels hit a HUGE rut in the road and nearly tore your front suspension out!!!

The ECU stops fuel flow right where it is!!! Full throttle, lots of gasoline....Fuel Cut scenario....NO GASOLINE.

Car still runs after fuel cut usually. It can scare the crap out of you, if its never done it before to you.

The ECU will "remember" that it has seen the perameters for FC and store the memory for if it ever sees to much boost again. Its good to RESET the ECU after it happens. It wipes the memory of fuel cut.

gsxtacy

 

[gsxtacy]

450's will get you by on the 14B, so no worries. Do get a Fuel Pump asap.

gsxtacy

 

[Wanted:SWGSXAWD]

gsxtacy-"The ECU will "remember" that it has seen the perameters for FC and store the memory for if it ever sees to must boost again. Its good to RESET the ECU after it happens. It wipes the memory of fuel cut."

Does this mean disconnect the battery?

 

[gsxtacy]

Completely +/- disconnect, for more than 1 minute.

gsxtacy

 

[LiquidGS-T]

So now i gotta ask... Does the car actually sense that it doesn't have enough gas or does it think, "18 psi? Your stock pump can't handle that dipsh!t!!!!" and then shut off. Cause i had a walbro 190 on my t-25 and no matter what boost i ran it at, it never cut on me.

 

[DSMeclipse4G63]

So now i gotta ask... Does the car actually sense that it doesn't have enough gas or does it think, "18 psi? Your stock pump can't handle that dipsh!t!!!!" and then shut off. Cause i had a walbro 190 on my t-25 and no matter what boost i ran it at, it never cut on me.

When the ecm/ecu reads too much air from the MAF it senses a danger situation to the engine and shuts off fuel. My car usually reeads about 32.xx lbs/min of air before I fuel cut, once I logged 34.94 lbs/min of airbut 99.9999% of the time when a dsm reads from 29.xx-32.xxlbs/min youll hit the cutoff. You ask then how are people with afc and link not getting cut at 24psi? well with bigger injectors and a tuning device the injector duty cycles arent as high cause the injectors can flow more(60% injector duty cycle for 550's= higher duty cycle on 450s). With the injectors flowing more the ecu sees less injector duty cycle and thinks well if my duty cycle is so low then therwe must not be a problem. Afc also helps to minipulate the air/fuel curve and trick the ecu it playing a planned out map that you set.

Is it possible to fuel cut with bigger injectors and pump? yes if you have a 190 and 550s and are running a hugge turbo at high boost you will most definatley cut. to answer your question it is VERY hard to cut on a t25 adding more fuel makes it pretty much impossible, so theoretically you can run all the boost you want on the t25 and not cut, although I dont recomend running over 14psi...

Andrew

 

[Spellmen]

450's will get you by on the 14B, so no worries. Do get a Fuel Pump asap.

gsxtacy

I wouldn't say that. I was outflowing 450s at 15-16psi with my mods so I had to get 550s, granted, most people would have upgraded their turbo before they bought what I have already

 

[olmytsi]

not true about the t25 and fuel cut.

 

[olmytsi]

you can run all the boost you want on the t25 and not cut,
Andrew

I have hit fuel cut on the t25 at 18psi at least 3 times.

 

[DSMeclipse4G63]

I have hit fuel cut on the t25 at 18psi at least 3 times.

you fdont have a fuel pump, read my post again. It says with a FUEL PUMP you can pretty much run all the boost you want. but I dont recomend it.
Andrew

 

[olmytsi]

i missed dat. yea im sure with a fuel pump there is no way u can hit fuel cut on a t25.