nillviod

Drivin my car today and i notice the turbos are boosting a little high.. i have a vdo (i think) turbo gauge is it possible that it is off few on the psi?

also the psi seem to climb to 10 at only 2/3 throttle (the 1st one)
the second one hit 13.5psi in 3rd gear full throttle, just seems way too high

is this problematic ? anyhelp would be appreciate please - im really worried

thanks
(im running a stock car with a new engine, m2 cold air intake, ss downpipe, exhaust syst3ym - turbos are NOT new car has 85k)

BigIslandSevens

iTrader: (4)

13.5 psi is too high for a stock ECU. you need to keep it at or under 10 psi. Do you still have the cat on the cars exhaust system? BE CAREFULL!! Your new engine is in danger. Does the boost slowly climb above 10 psi in third gear? Or does it jump there quick?(spike)

nillviod

jumps in a quick spike

nillviod

why would it be doing that

nillviod

ive seen it do perfect 10-8-10 in full throtle always, it was just today that first turbo hittin about 11 and 2nd about 13

rynberg

Probably because it's getting colder. Your mods increase air flow through the motor (duh!) and so you are now experiencing boost spikes/elevated boost. You will need a boost controller, manual or electronic to maintain safe boost levels.

The other thing it COULD be, is a leak in the vacuum line running from the primary turbo housing to the wastegate actuator. Check this line to make sure it has a good seal and is in good condition. If it is, you need a boost controller.

BigIslandSevens

iTrader: (4)

Again....Do you still have the cat in the exhaust? When i added a DP and cat back, Intake the prim. boost was creeping to 11-12, sec. was 10. All cars are different. They react to "mods" differently. You may want to have a vacc hose replacement done for the reliability of it.( Since you have boost , you don't have a leak problem) I would reccomend getting a boost controller. I was able to smooth out the boost pattern in the car I reffered to earlier.( stoped creeping and spiking) I put in the profec B spec 2. EDIT: Rynberg, i didn't even think of temp change!Good point!! It is always 80 out here( takes temp change out of the equation) And i agree with the actuator line inspection. Thanks for singling that out!

911GT2

With the exhaust mods you have it is not uncommon to see a boost spike at transition. Is the spike right around 4500 rpm? And does it go back down after (like 11-8-13.5 then jumps back to 10 or 11)?

If its a quick spike, its doing that because the ECU has no Mass Air Flow sensor to rely on to tell it how much air is running into the engine at any one time. It assumes the car is stock, and so controls the wastegate as if the car was stock. You have more airflow than a stock car, so your second turbo builds boost much faster than it used to, and the ECU is opening the wastegate at the same point as if you weren't flowing more air. That level used to be 10 psi, but now it's somewhere around 13.5 psi. You need something to tell your wastegate to do otherwise, like a boost controller.

But stay off the boost until you can get a controller, either manual or electronic, and or an ecu to ensure you're not running lean at those levels. I'd recommend either getting an electronic boost controller like the GReddy Profec B, or Profec B spec II, or a manual one that you can make yourself with parts from Home Depot. Theres a good writeup on here somewhere for the HD one, search for those.

911GT2

Guess I was a little slow with the reply. But yeah, cold can have a lot to do with it too. Colder air is denser = more boost.

nillviod

so you dont think its a leak? ill get a boost controller but can someone explain real fast how to check for a leak i want to make sure they arent leaking (i can look it up i guess if n0 one cares to type a desciptive explanation :p)

nillviod

great now i opened the hood and i hear this gurgling sound coming from the front left and the center... :| any ideas

nillviod

nevermind im a f00l i used search said its normal

nillviod

as of right now i guess ill get one of those two boost controllers and just watch my psi guage and not let it pass 10-thanks for the help

mr g lord focker

Another option is the Power FC. It is a boost controller as well and will also help you get the most out of the other mods you have. Especially if you are planning on more mods you will want to get a worthy ECU like haltech or PFC instead of just the boost controller in itself.

nillviod

ok thanks ill check out the prices on all this

SleepR1

Power FC with your mods would be helpful...and you can upgrade when you want to do the V-mount IC/rad, midpipe, bigger injectors, and beefier fuel pump

BigIslandSevens

iTrader: (4)

I was under the impression that the PFC boost controller was not that accurate or good of a boost controller with the twins. Is this true? I would hate to see you spend the money on the PFC JUST for the boost controller feature. I do think it should be top priority if further mods are going to be done.

nillviod

bigisland yes i still have the original cat

clayne

nill,

Most likely it was a low intake air temp at the time you got on it (probably right after the engine came up to operating temperature but the intake charge was still cold).

You're on the edge with 3 airflow mods and stock ECU. The "safe" limit is 2 (intake/exhaust, downpipe/exhaust, intake/downpipe).

SleepR1

The Power FC would be needed, as nill is on the borderline now with his mods. The Power FC boost control uses the precontrol and wastegate solenoids and actuators. You adjust the base duty cycle. In my experience the Power FC has done an excellent job with dp/main or hi-flow cat/cb. Once you replace hi-flow cat with mp, there is a 1 to 2 psi spike past your target boost, during transition. Before and after transition, target boost is achieved accurately. I don't believe in spending more money than you have to. The Power FC does fine job in controlling boost, so why spend another $500 for a Profec Boost controller? Besides I've read the Profec doesn't control boost well with sequential twins (it gets confused). If you go single turbo and plan to run over 1.2 kg/cm^2 (17 psi) boost, upgrade your MAP sensor and get the Power FC boost control kit. If you go nonsequential twins, then go Profec B, or Apexi AVCR. For the sequential twins, and boost pressures below 1.2 kg/cm^2, Power FC's own boost control feature is the best game in town....

BigIslandSevens

iTrader: (4)

Thanks SleepR1! I just heard arguments both ways. I agree he is on the edge of needing the PFC anyway. It is a great ECU in my experience with it. I just used an AVCR for BC.EDIT: Half your post didn't show up for me before. I will Disagree that the profec doesn't do a good job controlling boost on the seq. set-up. I have it on a car and it is smoother than stock. The car has DP,CB,MP,intake,FMIC,. It never gets above 10 and no spiking or creeping. All on the stock ECU. But i've said it before no 2 cars are the same.BTW...$500 is way too much for the profecB Someone didn't like you with that price Jason at the Rx7 store has them for $315 now.

David Beale

I have the midpipe, downpipe, and HKS Superdragger exhaust, and just installed the PFC and don't get a spike. I just get 12 PSI. Been trying to tune it back down to 10 as fuel around here is not too good. I was really impressed with the PFC. It's a different car! Much smoother and easier to drive (and more powerful too - what a combination). This is what the RX-7 should have been from the factory!