have a boost spike now due to cat delete want to know how to fix it car does have a power fc and its a 93 rx7

 

Put the cat back in.

 

boost controller

 

remove the restrictor pills until you get an upgraded ECU ,

 

he said he has a power fc...

 

If you're on the stock twins, it's probably boost CREEP, not spike. Put the cat back in or port the wastegate. A BC won't help.

From the stickys..........
Boost Creep - A steady increase in maximum boost, usually at higher rpm. Creep is caused by the exhaust flowing more than the wastegate and turbo can control. The (only) solution is to either restrict overall flow or enlarge the wastegate opening. Installation of a cat-less midpipe often cause boost creep.

Boost Spike - A sudden surge in boost, usually appearing between 4500 and 5000 rpm. This is dangerous on stock ECU systems, which sometimes do not detect and compensate for this extra boost before detonation occurs. Boost spikes often begin to occur after installing a modification that increases flow, and can be resolved in most cases by installing a better boost controller.

 

darmn my bad ,

in that case go into power FC commander , go into boost -> go into duty cycle for all 4 settings I'd lower the duty cycle from 90 which its at stock , to maybe 70% and gradually up it until you start to creep past your target again .

 

You need to port your wastegate or put the cat back on.

 

what you need to understand is why you're getting boost creep....

when you removed the cat, you alleviated the backpressure that is required to maintain 10lbs of boost; the stock wastegates are not large enough to bypass enough exhaust...that's why most are suggesting that you put the cat back on or port the wastegates, and why a boost controller won't help

you might have a PFC but i'm not sure if it'll apply appropriate fuel based on what the boost is, i'm assuming you also have a base map as well..

 

Sorry let me rephrase ,

There are various things which you can do .

first thing is replace the cat. this will stop the boost creep .

second thing you could do . remove the Pills from the turbos this will make the turbos run off wastegate pressure so 7/8 PSI even with creep it will stay in the safe zone .

Third option . if you feel ballzy and confident enough . and have a wideband . which you SHOULD HAVE . reguardless . You can try to tune a bit using the commander and the PFC .

read some of the threads reguarding this subject and edjucate yourself . on how it works.

4th option . remove turbos PORT THE HELL OUT OF YOUR WASTE GATE , ( with this option you will more then likely still need to tune your PFC ) to make up for the increased flow .



5th option Pay someone to tune the car . results wont be ideal , until you port wastegate because you will need to bleed air early to combat creep spool will not be as great .



6th option High flow cat .


These are some of the options which you can do in order to keep your engine from going boom .. Choose which one you think fits you best

 

Remove the restrictor pills, install quality manual boost controllers(Hallman RX), search for Damian's boost control thread for sequential twins, make sure to disconnect the wastegate/pre-control solenoids, and block off the lines coming out the 3 o'clock position on the wastegate and pre-control actuators. With good MBCs set up correctly you can control spike and creep really well even with stock ported wastegate.

 

alright so I just talked to my tuner he said I should just take the wastegate pill out and go with a greddy profec he said he could do it just fine no problem without porting the wastegate any feed back would be great

 

you can just use the Power FC's boost controller . other boost controllers have their benefits but if all you want is to stop the boost spike you shouldnt need a new boost controller

But new boost controllers do have their benefits , Like having low / high boost settings you can switch to .

 

I doubt he has the PFC boost controller as they are rare. I laid out clearly how to control boost on both turbos and spike.

 

does this always happen when u remove the cat and run on stock turbos? or it just depends? I am about to install a 3in downpipe with a 3in resonated pipe to an oem muffler... you guys think ill be okay>

 

there is a good chance it might happen to you . the stock exhaust is the only thing that might maybe save you . but there is generally a 3 mod rules .

you can only do 3 modes before you need to upgrade your ECU

intake exhaust , downpipe ,

intake downpipe , midpipe

so on if you free up tomuch flow its just tomuch for the wastegate on the stock turbos and the duty cycle needs to get adjusted

 

THe pfc comes with a boost controller for the twins it uses the OEM system just lets you play with it a bit .

Its not as elaborate or fine tuned as the EBC's out there . but I've had no issues making it do what I want.

 

should I take 1 pill out or both for now

 

both

 

I think you are confused. There is a seperate boost controller option (Power FC Components, Boost Control Kit) and you can make some changes without it but you don't get any real control of the wastegate.

 

OP, you still haven't even described the issue in detail.

 

You can set a boost a parameter , and you can manipulate when the waste gate starts to open


for the primary turbo it controls the prespool ..


say you set it at .85 . and duty at 90%

when it gets to 90% of .85 or .765 it starts to open .

because the waste gate is small you need to make it open up much earlier ,

i believe I have mine set so it opens up at 67 %

if boost goes .2 over target it will trigger fuel cut

the higher the % the quicker the spool because it only starts bleeding air off after it reaches that % , so my wastegate starts to open at 67% of target boost . in order to combat spike / creep . its not perfect but you can make due .



now what about the MBC, what does an MBC do ? it replaces the pills which restrict air . it tricks the ECU into thinking its receiving a certain amount of pressure . by adjusting the dial

but it uses the preset % for wastegate duty on the ECU

an MBC really isnt going to do anything more then the PFC with a commander can do .

 

Not worth the argument so ill leave it at this. You will never get the same boost control and accuracy with a PFC using the factory solenoids as you will deleting them and using quality MBCs for the primary/secondary sequential setup.

 

if it creeps up to, lets say 13psi, why not get it tuned for 13-14 psi?... i (at one point) had bad boost creep bad because i took out the the cat, i ended up adding a restriction plate i made until i could get it tuned

 

so mbc vs ebc this is what I need to know what of the 2 will have the best control for my twins combined with my power fc //////////greddy profec ebc or rx mbc and can I still take the solenoids out with ebc