Alright, ever since I got my car up this year I have been having issues with the boost and a few other things. Alright, well Let start with boost. But first I will give you my power mods. Full 3” Exhaust, dual intakes with hard piping. A large XS intercooler (I got spikes with the stock one too) Ignition Amp, and a PFC. 850cc primaries, and 1300 cc secondary. All emissions stuff taken off. (that’s why I checked the rats nest last night)

I Can't seem to limit my boost at all anymore with my manual; boost controllers. they are setup the right way but they wont stop the car from hitting above 15 psi when the secondary turbo kicks in. Obviously the good ol PFC fuel cuts me right away...Now technically should be able to control my boost with a manual controller no matter what right? Heres a small detail, this summer I had gotten a set of so called "decent twins" from the forum… bastard greensupra93 or whatever his name is played me. The dual nipple coming from the primary turbo inlet housing was JB welded IN! Its the one that goes to the actuators. My assumption is that it has something to do with that becasue my vac lines I checked last night and look just fine too me. If it isn’t the nipples leading to the actuators what else could be causing a boost spike. BTW I wasn’t getting these with my last set of twins and my over all set hasn’t changed since. Is it possible there is a leak in the nipples and since the right amount of air isn’t hitting the actuators it keeps allowing them to boost more and more?

Also I got a new wiring harness this year and I haven’t been able to properly adjust my TPS to that magical number because the number that is supposed to read 1 volt closed and 5 open reads far too low when closed, but the lower volt number that read .4v when closed reads point .4 So what do you guys think the problem here is, do you think I have a short somewhere?

 

turbos ported? if not ur probably creeping too

 

I thought about that, but I never had creep with my last set with the exact same setup. Is it creeping when the boost reaches 15psi only by 7000 rpm or so?

 

Your boost is creeping, and no a boost controller cannot stop that. Either that or the wastegate actuator line is disconnected/loose (still will likely be creep though).

 

Checked my lines to the actuator and everything checks out. My feeling is the actuator is etiher stuck..broken...or the nipples are losing pressure. Can't check now for sure too late but I will go over it once agian tomorrow morning. Like I said, to have boost creep now is just strange of all times, seeign as hwo nothing in my setup has changed and i was doin just fine last year witht he same setup minus the PFC.

 

Bah I really dont wanna take the turbos apart to port em. Pfff... POS mazda turbos...Single 500r, gt35r or even a gt40r is looking better and better at this point

 

Is it possible the replacement turbos are making better boost than your old turbos did. If they made the same boost I would think that you wouldn't be having these issues either.
With a full exhaust and open intake, everyone on here has had to port there waste gate to dorp enough boost not to creep....perhaps you thought you would be an exception to this rule. My suggestions.
1.) Port the waste gate or,
2.) Put the old turbos back on.

 

Im probably gunan port the old turbso and put em back on.
Or mayeb I'll just say screw it to this constant headache. I took the PFC boost limit off and the boost creeps as high as 20 psi + good thing I have the fuel maps to keep up with it...I didnt not feel I was going to be an exception. It owuld make sense why now of all times htough. Mainly because of the fact my engine now puts out more power with a slightly tuned PFC...its obviously gunna out flow stock.

 

Are you sure your wastegate is physically connected? Your fuel maps are not good for 20 psi so stop deluding yourself.

 

Yikes! 20psi?

My manual controller setup keeps me around 13-15psi. The PFC fuel cuts over 15psi, and I haven't hit that since I made adjustments for the new SMIC.

 

wastegate should stop at a point.
not sure what factory is.

 

I guess it varies. I read in couple of places that suggested the stock turbos can creep up to 17psi and beyond if you are not careful.

I wonder how flow rates (or lack thereof) contribute to boost creep. If the engine cannot consume the air as quick as the turbo compresses it, pressure.

 

Not deluding my self AFRs, were good all the way through, made sure. Not stupid enoguh to keep hitting 20 just wanted to know how bad it creeped. I am stayign off boost now though something is def wrong with the waste gate though. The way the waste gate is setup, is it only affecting the larger second turbo?

 

I would test the boost controller solenoid or simply replace it. Also test the wastegate actuator.

Dave

 

Wire the wastegate flapper open and do a test drive. If it still hits 15+psi, then it IS creep.

 

Yes you are because the stock 2-bar MAP sensor is only good up to 16-17 psi...anything above that reads as 17 psi. Therefore no matter how much boost you are hitting, the timing and fuel maps are the 17 psi maps.....

This is without the fact that running boost pressures that high on pump gas will blow the motor no matter what the map is.

As I pointed out above, you have some kind of mechanical problem, but you almost certainly ALSO have creep.

 

I think I just fixed it kind of. I was checkin out my MBCs and noticed one of them was assembled wrong internally...I think I may have done this a few days ago when playin around with them. Btw. Would a 3bar map sensor be over kill for stock twins? Or added safety? Might pick one up this week. Anyways I was just drivign around and I realized the lasttime I did some tunign I was using the stock Intercooler and that it was creepin to 15 by 7000rpm where as nwo I have the much larger XS power one and It is obviously coolign the air more efficently or at leats passing it through that its giving me such massive creep but only when the second turbo kicks in. I also think I just destroyed my pilot bearing so yeah.

 

Well thanks for the help rynberg. I understand that going over 15 psi on pump is bad idea believe you me I know this all too well. Like I said hitting 20+ was more of an accident and what I ment to say was I was glad I had enough fuel at the moment that the engine didnt pop. with 850cc and 1300cc injectors it seemed okay when I checked my AFRs and my knock. I had my upper RPM range set to a ton of extra fuel at the time becasue when I first put the PFC in went ahead and just turned up the fuel via the RPM range and gave a ton of fuel at the top end. I believe this is the reaosn why i was okay for the most part at the time. Its not like I'm saying, "Oh gee TEH H4x I IZ TEH hit 20+ psi AND make teh mad p0W3r sW337! i GUNna sm0K3 3M 411 now!..Too harsh Rynberg, you come off too harsh on here.

 

I'm just misunderstood...

Glad you found the cause of the problem. IMO, yes, a 3-bar is overkill on stock twins because it is pointless running them past 15-16 psi anyway. Sounds like you had the PFC set safely -- good job!

 

ArigATO \(^O^)/ But woudlnt it be good to have the added safety of knowing if youa ccidently overboost or creep and dont notice it right away your pfc coudl be tuned at the higher psi range to be heavy retard in timign and larger supply of fuel?

 

Well, that's what most people use that last row for....but the PFC fuel-cut should be kicking in before there is an excessive overboost. Speaking of which, I'm wondering why your PFC let you hit boost that high without cutting. What is your target boost set to?

 

Uuggggghhh...that i did indeed mess with to see if it was fuel cut that was cutting my fuel. And then I saw just how high it creeped. I've set it back down to 15 PSI since.