ok i have a 93 touring...love it! anywayz my power mods are later version pfc(base map),catback,and greddy pulleys?? well im buying a dp and mp soon, it comes in a combo. right now my car is running on 3 catalytic converters(previous owner) the precat, hiflow cat, and a normal cat welded on the catback(apexi n1), if i remove the precat and hiflow and replace with the mp and dp, will i still see some sort of boost creep? keep in mind i will still have 1 stock cat thats been welded on the catback.... thanx

 

I'd say if you still have one cat, you should be fine. Most of the time, replacing the cat with a midpipe is what causes boost creep... but in your case, you still do not have a straight through exhaust so you should be good to an extent.

 

WTF? THREE cats?!

I'd remove the precat, get an exhaust that isn't cobbled up with a stock cat, and leave the highflo (I assume it's on the midpipe as usual?)... no idea why someone would weld a stock cat onto their catback. Is there even an airpump line going to it? Make sure there's one going to the highflow, and ditch that other nonsense.

 

Not trying to jack your thread, just want some clarification here. Will a bone stock car with no engine management/fuel overboost with a turbo back exhaust (including highflow cat, NOT a test pipe) and an intake? What needs to be done to prevent running too lean with these starter mods?

 

If you running stock twins and with DP, MP, and Catback. You need to port the wastegate to prevent a boost creep.

 

The presence of boost creep with a full exhaust (dp, mp, and cb) seems to vary from case to case. I have seen posts where some report boost creep with a full exhaust while others report none.

I’m currently running intakes, full exhaust, and a Power FC to manage it all. To date I have not seen any kind of boost creep and have been able to manage my boost levels and duty cycles very well by just using the Power FC.

Due to the fact that you are keeping the main cat and are still on the stock intake (from what I read) I would expect you to see elevated boost levels, but most likely not boost creep.

 

Make sure you fuel filter isn't too old and watch your boost gauge, especially on cool mornings. Depending on the car, you might get some spike and need a boost controller.

 

I was planning on using an open element air filter with hard intake piping, my PFS catback, a new downpipe, and the factory main cat section. I have stock fueling and stock engine management. No boost control or anything like that either. Do you really need engine management for just an intake/exhaust combo w/factory main cat? Shoudl I be worried about engine longevity with this? Any easier solutions than spending 1000$ on electronics to manage my 100$ in mods or porting my wastegates?

 

From what I understand, I don't think you'll pass California emissions with no cat. Could that be part of the reason why the previous owner had all that crap on there?

 

Sorry ArmitageGVR4 my original post was directed more towards JD Smooth83's initial question.

To answer your question, no a fuel management such as the Power FC is not required. It sounds to me like you’re trying to manage your boost levels and modification costs without breaking the bank (This is not a bad thing). In your case and with your mods I would recommend doing a search for a homemade boost controller (home depot boost controller).

If your managing your boost levels properly you should have no worries.

 

You NEED to have a boost gauge hooked up so you can be sure it stays well regulated to 10 or 11psi. If it's creeping higher, you will need to port your wastegate to handle remove the creep problem - but it depends on the car if that is necessary.

Dave

 

So the stock ECU can't compensate for additional boost without some sort of engine management huh? Even if you beef up the fueling system? I'm so used to my 4g63 where you can double or triple the factory boost without using any engine management at all and be fine.

 

Yes, it's all in the FAQ. The stock ECU cuts fuel at 12psi, unless it's a spike that happens too quickly for the ECU to react - in which case it goes lean and tends to grenade engines.

Dave

 

Gotcha, I've been doing a bunch of searches/reading on boost creep and it seems that most people agree that a boost controller i necessary in order to limit boox to no more than 10psi regardless of what bolts-ons you have with no engine management.

My experience is that boost controllers are used to fool the OEM wastegate actuator into seeing less pressure than there really is and thereby opening later, increasing max boost. Therefore, how can the boost controller be used to open the wastegate sooner in the FD? Is it something to do with bypassing all the wacky factory vacuum nonsense? I'm assuming that the wastegate is actually sprung pretty low and all that the factory vacuum nonsense actuates boost just like boost controller? Thanks!

 

If you want a cheap, affordable boost controller, just get a manual boost controller. They are very inexpensive.

 

Boost CREEP and boost SPIKE are two different things. A boost controller will usually cure spike, but as dgeesaman indicated, creep can only be addressed at the waste-gate.

 

Ahh, but boost creep is a special case, not associated with boost controllers. A boost controller is what adjusts/controls how open the wastegate (or precontrol) is. Boost spikes can be reduced/eliminated by upgrading to a controller that responds fast enough to avert the spiking.

Boost creep happens when the boost controller has the wastegate held wide open, and the flow is still not enough. It won't matter what kind of contoller you have, when the valve is held wide open that's the limit. This is why porting the wastegate fixes it - just a few percent increase in area avoids choked flow.

You can use a boost controller to increase or decrease boost. Since bolt-ons decrease flow restrictions, this leads to the compressors generating higher boost pressure, and this must be watched anytime you add a bolt-on mod - hence all the discussions about spikes and creep and control.

The problem is that the stock ecu is an open-loop boost controller using a somewhat special arrangement. The advantage is robustness and safe failure modes (when it breaks it tends to cause no boost, rather than too much). The disadvantage is that it's tuned for a specific flow range - much beyond the stock flow and you'll get poor results. This is why the PFC and other ECU options are limited as boost controllers - the actuator springs and bleed orifices are tuned for a 10psi 255hp car. "Real" manual and electronic boost controllers work independently of the ECU - the downside is that the user must adjust them, but the advantage is that the user can adjust them

Dave

 

So what I'm hearing is that the only *real* solution to safe operation increased airflow is to upgrade the computer with fuel maps for with increased boost levels or to port the wastegate -- either great expense or great effort. Great.

 

If you wanna play, you've gotta pay .