Monsterbox

iTrader: (6)

ok, just installed a midpipe...set fuel cut on my pmc to 13lbs..i took it out last night (will not drive it till this is fixed again!).....car had already been spiking above 10 with intakes pretty bad


- floor the car at 1.5k...reaches 14lbs and fuel cut by 3k on primary turbo!
- if the car is heatsoaked really really bad and I can get past the primary...at 4500rpm the secondary will shoot up to 13lbs when it comes on then drop back to 10 and hold rock solid to redline

is this creep or spike....keep in mind i had the same issue just not as bad before the midpipe

should i purchase electric boost controller now or get a restrictor plate or both which should i do first?

moconnor

iTrader: (14)

So you are using fuel cut to control boost?

Fsunoles06

well, unless you can pull your turbos and port the wastegate, you should not have a midpipe with out some sort of restrictor in the exhaust and a boost controller.

Just get rid of the boost creep before you lean out your a/f ratio and blow.

Fuel cut is not going to control boost, at all.

Monsterbox

iTrader: (6)

ok hold on

PCM controls boost (electronically...i set fuel cut at 13lbs for safety (yea i notice it doesnt control it it shuts the car off.

is it spiking or creeping?

Monkman33

iTrader: (28)

um, get both.

restrict your exhaust until you do the necessary supporting modifications (fuel, EMS, etc...)
and get a boost controller, or two manual ones.

read this

and setting fuel cut to 13psi is not controlling boost. that is just plain risky. unless you have done the mods to support 13psi, and the extra flow of a mid-pipe.... wow.

Search is your friend. I don't even want to recap this.. and i haven't even been here this long.

and to be blunt, it really doesn't matter which one it is. you are adding more problems on top of other issues. why not fix anything that is wrong BEFORE adding more mods on top of it? Just curious?

RotaryResurrection

iTrader: (8)

Spike and creep are basically the same thing, boost generated above what the wastegate is set up to vent off. IT doesnt really matter what you call it, it's a bad thing.

HardHitter

iTrader: (4)

You don't have a boost controller?

My car is doing the same thing, and the good thing about having the boost controller is that you can set the controller back to 0 and retune it.

My car does the same exact thing (have stock cats though) and I just ordered a PFC to hopefully start controlling this before something bad happens.

You seem to have the right idea, which is correcting this asap.

Good luck

RotaryResurrection

iTrader: (8)

UH...no. A boost controller cannot lower boost, only raise it. IF your factory wastegate is set up to run 10psi but is creeping past that, a controller will do nothing to lower it. The problem is the size of the wastegate versus the efficiency of the exhaust, not how soon the wastegate is opening.

spandy

iTrader: (1)

Boost creep is when the boost keeps going and going and going (creep).

Spike is when it immediately jumps to say 14 (spike), and then backs down to where it should be.

This is what killed my motor, my wastegate is being ported next go around to support my mods....along with a few other things that need to be done.

Here is a fancy chart for you The aren't "correct" in a sense of the curve, but you get the idea.

dgeesaman

iTrader: (7)

No factory wastegate is set to run at 10psi. They are set at 7-8psi. Therefore any adjustable boost controller should be able to get you all the way down to 7 or 8psi.

As well, if your factory ecu and boost control are pushing above 10psi due to flow mods, then running a adjustable boost controller will allow you to lower it back to 10.

As for boost spike and boost creep being the same thing - sorta. Too much boost is dangerous, yes. Boost spikes can be more dangerous since they can happen too quickly to be cut off by fuel cut - so in that sense they are more of a problem. As well, boost spike and boost creep are caused by different things.

Monsterbox, let me understand: you were having boost control problems, and decided to install a midpipe?!?! Could have you have done anything worse!?! I suppose it's ok you've managed to prevent disaster with fuel cut, but what did you expect by opening the exhaust further?

As for the original question, it sounds like you could have both boost spikes and boost creep. Take off the midpipe and install a boost controller. Programmable ECU boost control is better than stock, but not good enough this time.

Dave

kashent

This is not true. Boost creep occurs when the wastegate simply cannot open far enough to reduce exhaust feed to the turbos. It occurs precisely when the wastegate is completely open.

Mahjik

iTrader: (1)

I don't believe dgeesaman was saying that a boost controller would stop boost creep. He was stating, with controllable boost on the stock wastegate, boost can be as low as the wastegate spring of ~7 PSI using a boost controller.

dgeesaman

iTrader: (7)

That's correct. No boost controller can do anything about boost creep.

My statement was in refute to the idea that a boost controller in general cannot adjust the boost level downward - I was explaining how it can.

Dave

Monsterbox

iTrader: (6)

ok wait let me restate this AGAIN

1st car was stock...had always read 11lbs at smashing the gas pedal and would come down to 10 (only downpipe)

2nd added aftermarket ECU (programs fuel control up to 13, 14+) its capable of mapping fuel at 17lbs of boost (would stay solid at 10lbs now)

3rd added hks intakes (started jumping above 10...to 11,12, 13 in a pattern of 12.5/13 - 11 - 10 to redline

4th Added Midpipe...what i think is happening is spiking at LOWER RPMS (13-16lbs so high sometimes so quickly fuel cut doesnt catch it)
when i first tested the car with midpipe it was heatsoaked and i was able to get into the 2nd turbo w/o the spike and it pulled 10lbs to redline numerous times


car began clogging up in the cat really bad this winter (90k miles on it)...so i HAD to replace the cat...i found a REALLY good deal on a resonated midpipe (way cheaper than any hiflow out there)


should i try a boost controller to control this spiking because i do not think i am creeping...Will it do more than my ELECTRICAL PETER FERREL ECU BOOST CONTROLLING

and finally (and most likely) if i hook up the boost controller i should expect:
no more spiking, if i set it at 7lbs it should pull 7 lbs and gradually increase to redline (if it creeped) it shouldn shoot to 16 in 5th gear like it is now when i lightly tap the gas????

RotaryResurrection

iTrader: (8)

IF you still have the factory boost solenoid hooked up to the stock wastegate, try unhooking it, and also remove the pill from the wastegate line. That should increase the wastegate's response, while lowering base boost the wastegate 7psi spring pressure to give more headway for creep.

IF you still creep/spike, then there is nothing more you can do except port the wastegate.

The factory WG solenoid basically IS a boost controller. It takes the 7psi wastegate and makes it run 10psi. It is controlled by the ecu, preset to 10psi. Your PFS purple motor eater also interacts with the solenoid, which is how it raises boost when you turn the dial.

Remember when I said no boost controller can lower boost? I was correct. IF you have a wastegate spring set at Xpsi, the boost controller can only raise boost above X, it can never take any away. Now, in this circumstance, your wastegate is set to 7psi, yet you already have a factory boost controller installed (WG solenoid) that is raising it to 10. An aftermarket boost controller installation would have the WG solenoid taken out of the loop altogether, at which time boost would fall to 7psi until the new controller was readjusted to raise boost up again. If you just want to lower your stock boost to the 7psi wastegate spring, well you don't need a controller, just unplug the wastegate solenoid.

dgeesaman

iTrader: (7)

OK, perfectly fine.

Yes, in theory it can do that. (I'd use a PFC, but that's another story...)

Not too surprising. These are boost spikes. Boost spikes are caused by the limiations of the stock boost control solenoids. An electronic or manual boost controller on the wastegate should stop them.

Here's where I think you confused a "really good deal" with a cheaper part. Now you may be pushing boost creep and have to do significant other mods, when another stock cat would have left you just fine.

Yes, you should do that, and it will be better than the PFS by far because the PFS is limited by the stock wastegate solenoid.

That's right - if you are free of spikes, but still have boost creep, it will behave like that. If you know to watch for it, boost creep isn't all that dangerous since you can lift off the pedal. It's those sudden spikes that scare me most.

Dave

dgeesaman

iTrader: (7)

I guess then we're saying the same thing then. The first time it read as if a boost controller couldn't get his 11-12-13psi boost any lower, which is untrue. But if you're comparing it to spring pressure alone, you're right a boost controller can only raise boost above spring pressure.

For anyone else reading this, note that taking the wg solenoid out of the loop means shorting the vacuum line leading to/from the solenoid, but keeping the vacuum line fully connected and without leaks. I personally unplug the electrical connector on the wastegate and leave the lines in place since that does the same thing with less risk of error.

BTW the stock wastegate spring is fixed at 7psi. It's not adjustable, so discussing the spring setting is irrelevant.

HardHitter

iTrader: (4)

It spikes if you lightly tap the gas? Is that possible? I thought our cars pedal is based on the force. Example, if you barely step on the gas, it will only put certain amount of acceleration, where as some cares no matter if you barely hold the gas down or slam it down, it will have a constant impact. Or maybe I just heard this somewhere and it's totally wrong?

For me, it only spikes as if I am cruising in say 5th on the freeway, and then I down shift to 3rd, cruising in the higher rpms in 3rd barely giving it gas, and then if you push all the way down on the throttle that's when it will spike. Yours is if you are barely on the gas?

Monsterbox

iTrader: (6)

well not barely....but any more than quarter throttle it hits 10lbs+....put it this way..5th gear at 2.7k rpms....floor the car quickly (instant 16-17lbs before the fuel cut can register in cold weather!!!)....that sounds like more than boost creep


DGEES YOU ARE THE MAN, I sincerely appreciate your detailed reponses...I am going to purchase a boost controller now!

and... if i'm understanding this correctly

If i am trying to differenciate b/t spking and creeping (welll im' spking so harshly now i cant keep the gas down to see if i'm creeping).....so,

- until controller arrives, UNPLUG Electrical connector to wastegate solenoid, this will allow the wastgate to open at 7PSI on it very own...no controllers nothing...so this would tell me if a boost controller could possibly stop the spiking because the most it can do it change the boost down to spring pressure only?? and if it does control the spiking then i shall find if i have creep or not as i stay WOT on 7psi spring pressure

RotaryResurrection

iTrader: (8)

The stock wastegate is preset at 7psi. Put boost controllers out of your mind altogether. You need to try it at 7psi with no pills in the line (from the compressor housing to the wastegate actuator) to obtain maximum response and minimum boost. Now see how the boost responds. If it is still higher than you are comfortable with (I'd be comfortable with about 12-13) then you HAVE to port your wastegate. The problem would be the hardware, the actual size of the wastegate, and not the control system.

The only possible way to do better than that is to disconnect the wastegate actuator from the wastegate altogether and let the gate remain open at all times, which will make boost build very slowly. I personally could control my right foot easier than I can climb my *** under the car and disconnect the rod, though.

Simple as that. No boost controller in the world can change anything I wrote above. Adding boost controllers and solenoids into the mix only serves to raise boost above what is mentioned above.

FD3S2005

iTrader: (11)

yes with a boost controller you can lower boost to the stock wastegate spring... which is 7, but thats as low as you can set it.. the rest has to be raised

dgeesaman

iTrader: (7)

Both unplugging the wg solenoid and removing the pills will reduce boost to spring pressure. I'm not aware of any substantial difference, so I find unplugging it to be abundantly easier.

I agree with the test procedure of running at 7psi to remove any spikes and test for boost creep. It's a great idea.

Dave

Tim Benton

iTrader: (1)

If you have the PFS PMC and the weather got very cold like it did here, you'll need to retune the boost any to adjust for the cooler, more dense air. Creep usually happens in the upper rpm's when there isn't enough flow through the wastegate to bleed off boost. You have spikes right now is your going from 10 to 13.5 over a short rpm range, creep would be going from 10psi to 13psi from transition (4500) to redline.

Tim

Monsterbox

iTrader: (6)

guys i really appreciate it...im going outside now to remove the electrical connector from the wasgate actuator solenoid

so i shouldnt have to mess with the pill...i can try that as a last resort if the electrical doesnt do the job enough

this should be a sticky as ive searched & searched b4 posting this and found unclear info

RotaryResurrection

iTrader: (8)

Even with the wastegate solenoid out of the equation, the pill between the boost source (compressor housing) and wastegate actuator is a restriction placed there to slow down the wastegate's reaction time. After all the boost has to fit through a very small hole before filling the actuator chamber and opening the wastegate. IF you continue to have problems, removing the pill may help even more than simply unplugging the solenoid...or, it may not be necessary. But it COULD make a real difference.

You guys are making this out to be brain surgery...it's all right on the front of the primary turbo, it's not like it's hard to get to.