Apexi intake = overboost????
 

I don't understand. I've just finished the apexi intake installation and I've gone for a nice ride. My car keeps the boost pattern (10-8-10) with some little 11.5-12 spike around 4500 rpm. But with the intake all is gone. I'm scared! In third gear boost have raised 14 psi (keeping it for more than 1000 rpm). Obviously this is not good.
And one more thing. Sometimes I hear water boiling when I shut off the engine. Some slight sound in some hose. But today I've heared it louder, stronger. I've put on the key and the fans have started to work instantly. I think I'll need a CAI box, cos the lower filter is just on the lower radiator hose and breathing directly from the radiator fan...
Any advice? Has anybody had this issue with only an intake mod???? :uhh:

When you open up the intake, you get more airflow, and higher boost. Get a boost controller.

I know, I know... but, don't you think it's too much increase just for only an intake mod?

What other mods do you have?

My Performance mods are only catback + downpipe

a boost controller won't lower boost. I don't know why you're experiencing boost spike/creep w/ cat back and dp.

I had dp, midpipe, and 3" all the way back, the engine couldn't control my boost so i had to be really light on my right foot. I installed a cat & my PFC and it holds strong at 10lbs.

Some misinformation here. First off, you're at 3 mods on your car - intake, downpipe, catback. With that setup with the stock ECU, you WILL get boost spiking.

Next, a boost controller will help. The stock ECU's boost control map is VERY hardcoded, and will run away with the boost if you open things up. Putting on some sort of boost controller will take care of that problem.

The PowerFC gives you control of the factory boost solenoids, which will give you boost control to a good extent, but once you go farther (high-flow cat or midpipe) the factory pill-based boost control system won't cut it.

Anyhow, if you need something short term until you can afford a PowerFC, get a manual boost control setup. If you don't want to re-buy mods, get a good electronic boost controller. With either, keep boost at 10psi and the ECU will be mighty happy.

Dale

how does a boost controller lower boost if all it does is trick the factory ecu into thinking boost is lower than it is? I can understand how my PFC can lower boost but that's because it replaces the ecu.

An aftermarket boost controller will manage the wastegate and precontrol solenoids.

The PFC will no longer have any say in the matter, except maybe to fuel cut if the boost gets too high.

Because a good electronic boost controller doesn't "trick" anything...it takes over control of the precontrol and wastegate from the stock system, which the PFC will still only be able to control by itself without an additional boost control setup.

Okay, i'm a little confused. what i do understand is that a good boost controller takes control of the wastegate actuator away from the stock ecu.

What i don't understand is: Does *my* pfc driven car have any reason to have a piggyback boost controller?

His car has no pfc, no boost controller.

If it has enough mods to overpower the stock boost control system, yes.

Not if it controls your boost.

Personally, I believe my manual boost controller is more responsive and more consistent than my PFC, but that's just me.

I did not know it possible to push 14psi through the stock cat w/ the stock ECU. I ran same mods as you for a while on stock ECU with no spikes, but I guess every car is different.

The PFC controls boost just like any other EBC would, and has a multitude of other options, its a great investment for your car. I would recommend keeping a light right foot until you get a PFC or some sort of EBC. Don't waste money on an EBC if you plan to get the PFC in the future, it controls boost just fine.

Does your car slowly raise to 14psi and stop? Does it ever go higher? Or is this an instant 14psi holding steady?

Okay, for the record i have 3" exhaust turbo back, high flow cat, anti-rice cannon. I installed the cat last week, i installed the pfc yesterday. before i did that my boost controller was my right foot. since installing the cat and the pfc my boost holds strong at 10 lbs although some times at full throttle at the top of 3rd or fourth it'll creep to 12lbs. my peak injector duty cycle is 70.0%.

How can another boost controller actuate the wastegate to maintain my boost more efficiently than my PFC. I can understand doing it faster or what-not but if the problem is my unported wastegate then how would I fix that with another electronic box?

It won't make a difference, PFC controls boost just any boost controller. You are correct that the problem is now the stock wastegate. As long as your only creeping to 12psi you are fine though, just be careful on really cold nights.

Not necessarily. Every FD's stock solenoids/boost control will work differently, and from what I've seen, EBC's do a much better job of controlling boost spiking. At the very least with an EBC, you'll be using new solenoids rather than heat-weathered 10+ year old ones.
See above about boost spiking.

If the problem is specifically boost creep, then no, an EBC won't help.

+1

also PFC IS "NOT" A BOOST CONTROLLER. they sell additional add-on "boost controller kit" for PFC that cost around $350ish.

Anyone care to elaborate on this one?

As I understood that kit just replaced the already existing solenoids and gives you the option to quickly jump between a couple boost level settings. I can see that and a standalone EBC being useful for single turbo cars but what could it possibly do on the stock TT system? The only advantage I see with that or any other EBC would be the preset boost levels and new solenoids. I can adjust boost levels from my PFC already with the commander. If the PFC does not control boost than somebody please tell me what controls the boost on my car?

VERY SIMPLE ANSWER

i had the exact same problem

PROFEC B SPEC II fixes it completely

i had more severe spiking than you are experiencing...up to 17lbs of boost...i thought for sure that a boost controller could not fix it...well i was completely wrong

for now pull off the pressure tank and unclip the electrical connectors to the two solenoids u will run at 7psi on the primary turbo only (safety until a boost controller arrives)

pfc cannot control the boost as the solenoids do not respond quick enough even with interrupted duty cycling control

Makes sense that it would help control spiking but that seems like a band-aid to another problem.

You can easily get 14 psi on the stock ecu at lower rpms.

It's not just "setting boost levels"; it's about controlling the boost buildup more accurately. The stock control system is set up to build boost at a set rate, which is why spiking occurs with a certain level of mods. An EBC like the Profec B can alter the rate at which the precontrol door closes, controlling boost more accurately so that spiking doesn't occur in the transition phase.
Well, then the "problem" is modifying the intake/exhaust well past what the stock sequential twins and their system of boost buildup and control with both turbos were designed for...

i had the same problem also... i spiked to 17lbs and my car would jolt really bad... so i added a profec b spec II and fixed after some button pushin here, and button pushin there... it ll keep it 10.3psi alll the way... i have intakes, dp, and hks catback... you will be more than happy with the boost controller...

So than the PFC cannot alter the rate of the precontrol door? Just trying to learn something here and maybe help Victor kill 2 with 1.

Wow, a LOT of misinformation piling up here.

First off, the PFC has basic boost control functions. It can control the stock wastegate control/turbo precontrol solenoids - this can all be set up with the commander. You set the amount of boost and duty cycle percent, and there you go.

The stock ECU has, of course, control over the wastegate control/turbo precontrol solenoids, but runs them on a fixed map that was designed around a STOCK car. Once you open things up, those settings just don't work any more, and you have overboost.

You do NOT have to buy the boost control option for the PFC to have boost control. The option is just an aftermarket boost control solenoid (same one that comes with the AVC-R) and a higher-range pressure sensor to replace the stock MAP sensor. This gives more robust boost control, but the PFC's boost control is EXTREMELY basic.

Now, the problem is the stock boost control setup (two solenoids, pills in the vacuum lines to the wastegate actuators) just isn't very flexible. When I fully opened my exhaust, I had boost control problems that could only be solved by drilling the precontrol pill out a tiny bit, which is IMHO not a way to control boost. Dorking around with pills went away with the Clinton administration.

A good aftermarket boost controller ditches the stock wastegate control/turbo precontrol solenoids and the pills altogether. More advanced ones have even more features, like gear and RPM based boost setting (go AVC-R! :)).

So, to sum up -

Stock ECU's boost control - fixed map, boost spiking and loss of control with very minor mods.
PowerFC's boost control - controllable map using the stock solenoids, but boost control can be a problem with full exhaust/intake due to limitations of stock solenoids/pills
Aftermarket electronic boost controller - full and complete control over boost, ditch stock solenoid/pill system.

I think we've confused the original poster enough :).

Dale

Right on...

Apexi Intakes - little pickup...boost ok.
HKS DP - little more pickup...boost still ok 10-8-10
Greddy SMIC - same...
RD DT - real good pickup...2 psi more than 10-8-10

PFC & Steve Kan tuned.

edit. see next post :D

??????????????

Individually, each one of those mods will increase boost over 10-8-10. Any two of them will likely get you to 12 psi ............... NOT OK on stock ecu!!!!

Just to clarify, though: the vast majority of electronic boost controllers still use solenoids to activate the various functions. They just do a much better job of monitoring and activating them.

By themselves, not necessarily. A Greddy SMIC by itself may not increase boost if intake and exhaust remain stock. Same with a DP. Each car reacts differently to various mods. Combinations of the aforementioned mods, however, will definitely result in overboost.

Kento,

I disagree. I believe that any mod designed to increase flow, will increase boost. Certainly, one mod isn't going to increase your boost enough to cause a problem. As you/I/we stated, combinations may get you into a dangerous area.

If any single mod doesn't increase overall flow enough to overpower the stock boost control system, then you're not going to increase boost. The FD's stock airbox intake is very restrictive (as your stock airbox mod shows), as is the stock main cat. A DP increases flow enough to improve boost response, but not enough by itself to overpower the stock boost control system and increase overall boost level; when I installed my DP without any other intake/exhaust mods, I saw no increase in boost level. Other cars may see a slight increase. A SMIC like the Greddy may have slightly less pressure loss across its core, but if the stock intake can't get any more air in and the exhaust can't let it out efficiently enough, any flow gains won't be enough to overpower the stock boost control system, which is the primarly limiting factor for boost increase.

I understand what you are saying, but I still disgree with you. I don't think the stock boost control system will keep boost levels at 10-8-10 with any "significant" single mod.

Hey, this was my post! :pfanndina Sorry, just joking :icon16: Well, the fact is that I don't know why but my intake mod makes my FD overboost. That's the true! Combined with the dp and catback now I'm running in dangerous boost levels, still on stock ECU. The Pettit Racing is near, so I will wait until it's installed and in this way I will run the apexi intake. Next step should be a boost controller, but with the pettit I will run safely. Is this what I should do?

Check it once the Pettit ECU is installed. You may still need a boost controller.

Like I just said: when I installed my DP without any other mods (even stock catback), I saw no increase in overall boost level. When I removed the stock airbox crossover, then I saw a slight spike at the 4500 rpm transition. Other cars may be different.
Again, every FD is different, and some react to mods more strongly than others.
If you really are running at 14 psi, there is some debate as to whether that is pushing the stock fueling system too close its limit. IMO, you should be OK as long as you don't spike or creep beyond that boost level.

Great post Dale, that clears a lot up for me.

Victor are you considering a MBC?

Yes, but I'll install an electronic BC ;)

is there a way to tune a stock ecu? say a fd with tbe/apexi intakes?

Other than buy an aftermarket reflash not to my knowledge. However with only a couple mods the ecu should still be able to control boost. But- of all the mods i've done intake & mid-pipe were the biggest change. I've since installed a cat- as is mentioned in my previous post.

Mine hits 14-15psi @ transition and takes off like a raped ape, but I know it's unsafe so I only did it during the test drive... I know I can purchase 2 mbc's and control the pre-control / wg solenoids independantly, but with a EBC (considering two hallman's are $200), wouldn't I be better off going for a profec b?

Will boost be stable ~10psi throughout once dialed in?

my advice to you is to get rid of that of tho's filters man i had tho's when i had my stockers in and my intake temps were insanely high. because you get all the heat from off the radiator and all the heat from the engine bay. a nice air box will fix that. maybe it was just me but i couldn't stand them.

In theory Kento is correct as usual. In practice, Adam is right.

On FDs after this many years and mileage the true state of the stock boost control system is unknown and therefore results will vary. My 2nd FD worked fine for a while with the stock boost control system. Then one day it no longer controlled boost properly.

I've had overboosting with nothing more than a downpipe on my FD - especially in colder weather (30-40 degrees). On my old FC TII, it overboosted regularly with nothing more than an adam_c style cheap bastard intake fwiw and that was back in the day when it was new.

Electronic Boost Controllers are wonderful things. :)

i thought that boost creep cannot be fixed with a boost controller simply because the stock internal wastegates aren't open enough to let all the pressure release and that boost creep could only be fixed by porting the gates or welding them shut and getting an external wastegate?

Bear with me im a noob :(

Technically that's not true. Boost controllers operate on the basis of 'tricking' the wastegate source pressure into thinking it's lower than it actually is by bleeding off pressure, keeping the wastegate closed longer and allowing higher boost pressure to build up.

PART THREE!!!

The only thing that stays stock in your boost control system is the wastegate. So unless you have so little backpressure (mid pipe) that the wastegate is the weak link and *cannot* open fast enough (gain settings) your boost controller will be on top of things. It doesn't "trick" the wastegate source so much as it takes control of the wastegate source away from the ECU.