RotaryRockeTT

Ok, I went to my good old mechanic at Mazda Dealership today, I know I went to the dealer, but this guy knows the rx7 pretty good. Any way I told my mechanic that when I step on the pedal my boost goes shotting upwards toward 13 psi and etc, so he jacked the car up and inspected the Waste Gate and saw that there was a HUGE HOLE INSIDE IT!!!!! Does that mean that my WASTEGATE HAS BEEN PORTED OUT!!!!!!! **** IF IT IS SWEEEEEEEEEEET ITS ALREADY been done for me!!!!!!! let me know guys if thats the case!!!!

forcefed1

NO you can't see a ported wastegate by looking under the car. You have to remove the downpipe at the very least.
also if your getting boost creep having a large wastegate would help ELIMINATE high boost problems...
I would maybe say your wastegate actuator had a hole in it... not a real good way too see that either SO calm down and read the archives a bit more... on a similar note.. Went to the bathroom at work today ran into the maintenance guy on the way out .. mentioned about a blow out problem I was having... so he jacked me up and took a look.... my wastegate is still stock.... SWEEEEETTTTTTT now i can keep it that way

KZ1

if you are boosting 13 psi wihtout anything else done to the car, you will be saying "No Sweet" all teh way to the bank to pay for a new engine. As the WG actuator sees more boost it wastes or vents more boost. SO as force fed said, if you have a leak in the actuator it could goes overboosting on secondary turbos.

Ported WG reduce boost better they do not increase it. I would get tha fix as soon as you can if that is the porblem. Now, if the guy is actually saying that your WG had a whole in it, go get your car and never bring it back to him, he is a fool.

RotaryRockeTT

no guys, the mechanic did remove all that stuff such as the downpipe and etc, you see I dont get boost creep at all, what happens is when i step on the gas hard thats when my boost well go past factory levels, you see some of you guys dont know what boost creep is, boost creep is when you are saying costing at a certain speed and all of a sudden you boost starts climbing past a certain setting. Now whats happening with mine is when i step on the pedal lightly i will get 10 psi right away, if i stomp on the pedal my boost well go to like 13 psi. Now if the waste gate has a large hole that means its been ported or enlarged for the exhaust gases to vent out, any body else want to challenge this?

phatmonky

I will...

ask a question and then provide your own answer, real smart


You are holding a higher amount of boost. Your wastegate is STICKING, or some other occurence is keeping your wastegate form properly opening and releasing boost.
If the WG had a large hole in it, then you would be fucked! There would be a hole that is just leaking out boost!Yippee!! You would make little to no boost, and it would be very irratic (sp?)

My suggestion, ask a question, learn from the answer. Oh, and go tell your friend to explain to you what the hell he thinks because you are thinking about this all wrong.

poss

iTrader: (5)

boost creep is what happens when your wastegate is not large enough control boost to the desired level.
RotaryRockeTT, I have NO IDEA what you just said.

93TTRX7

if your wastegate has a hole in it...then you wouldn't get any kind of boost because it would all be going through that hole would it not?

turbojeff

iTrader: (30)

Look at the wastegate as a system. The wastegate is a little "flapper" and that flapper covers a hole. When people port the wastegate they enlarge the hole to fit the very edge of the flapper. So the wastegate IS a HOLE covered by a flapper. When the mechanic says there is a hole in the wastegate, is he talking about the hole or the flapper? Either way the description doesn't really make sense. If there is a hole in the flapper that isn't really good and isn't "ported". If he is talking about the the flapper not covering the hole that isn't really optimum (gives more lag) either but could be OK if your running a full exhaust.

The third piece of the system is the WG actuator, if this has a hole in it your WG flapper won't open or won't open at the right point, others suggested this.

Either way something is wrong, the problem, the mechanics description, etc...

Boost creep is caused by the exhaust side turbine getting to much exhaust energy. The WG limits the amount of exhaust the turbo gets by bleeding exhaust around the turbo(s) to control boost. Creep occurs when the WG is fully open and the boost still climbs, this gives more boost pressure and then more exhaust which gives more boost pressure and that gives more exhaust, rinse repeat...

Jeff

RotaryRockeTT

Well according to the mechanic, the wastegate had a huge hole in it. Now what does a wastegate that has been ported look like? isnt a hole that has been made larger? now tell me why then does my wastegate have a huge hole in it? my boost is fine, just that it increases to a higher than stock setting when i stomp on the pedal, now i forgot to mention that I have a midpipe and downpipe in place that could be causing this. But my main question is if my wastegate is not ported out than why is there a huge hole in it?????????

ttpowerd

On a stock ecu you should only boost 10 psi max. Anything over is a spike or a creep. If you have a ported WG then you would not even see 10 psi.

Also, running a mp without an ecu is not a good idea. Seeing 13psi is not a good idea on the stocker.

KZ1

I think I may know what your mechanic is talking about. All wastegates have holes in them. the wasteGATE, which is basically a little door has two parts. the primary door, which has a huge hole in it, and a secondary, enlarged piece, that is bolted to it, that moves back and forward to close the hole. This is STOCK, and the way it is supposed to be. When porting a wastegate you actually don't port thr wastegate, rather the hole that it seals which is in the manifold. so that when it opens there is more flow and more venting capacity.

What you are describing about your boost pattern sounds nothing more than the whole wastegate system is not working, ie. you are not venting any bosst or at least, not enough. if you have a midpipe, exhaust, intake , etc. then eveything may be wokring properly and you have reached the limits of the venting caapcity of stock wastegate. so, you have two options, get some fuel mods and run 13 psi, or try put in a manual boost controller and get the WG to come on earlier which effectivey may turn the boost down. or you can always try porting the WG manifold

potatobbq

Boost creep is caused when a fully-open wastegate can't divert enough gasses around the hot-side turbine wheel so the boost level continues to rise despite the best efforts of the wastegate.

For example, you're set for 10 psi, and when you floor it, boost quickly jumps to 10... But then as rpm's climb, the boost creeps higher and higher: 11... 12... 13... 14... etc.

neevosh

With a midpipe, you'll easily get boost creep to 13 psi with the stock control system. Do you still have the stock ECU? You should be hitting the fuel cut running that much boost.

potatobbq

actually... it's not "all of a sudden" that it climbs past a certain setting... it's called boost CREEP because it progressively starts creeping higher and higher because your wastegate can no longer divert enough gasses to maintain the desired setting. it's not like u hit 10 psi then immediately it climbs to 13 psi.

how much boost you get is dependant on how hard u step on the gas... simple observation would tell you this. of course if you just tap it lightly you will get less boost (say 10 psi) than if you quickly go wot and reach 13 psi so i don't know what your point is.

luneytune

Sounds like your boost pill has shifted or partially clogged with something. The smaller the hole the higher the boost and the turbo will act quite normal with a higher boost limit. Quite unusual but possible. Only if your not boost creeping the above would be true.

nocab72

Nice explaination of boost creap, thanks.

Now how about boost spikes?

I assume that is when you hit the throttle, you spike to 13psi, then it settles to 10psi as the wastegate does it's job and catches up, no?

K

potatobbq

Yup... in the case of the FD, if the secondary turbo pre-spools too much before it comes online, it will spike at the 4500 rpm point when it comes online. So at WOT, you might see 10 psi until 4500 rpm where it will spike to 13 psi then start to settle down at 10 psi again.

rx7speed811

wouldnt any competent mechanic know what a ported wastegate manifold looks like? im sure if he knows rx7s as well as you say he does, and a machined wastegate port is what he saw, he wouldnt just respond with something dumb like "HEY LOOK, THERES A BIG HOLE THERE!!! HA!"

just out of curiosity, why did you not ask the guy to elaborate some? if you had just asked him what he meant in his diagnosis, you wouldnt have to come ask here and be so defensive about all these peoples appropriate answers to your convoluted inquiries.

jimlab

This is a ported wastegate...



Unless your mechanic has removed and disassembled your turbo assembly, there's no way that he could see the wastegate with just the downpipe removed.

I believe that Jeff is right, and that what your mechanic is talking about is the wastegate actuator. If the control rod is sticking, the wastegate door (see picture above) will not open, and boost will rise to the limit of your exhaust system restriction. If you have catalytic converters and a restrictive muffler, you'll get ~13 psi probably. If you have no cats, and a free flowing exhaust, you'll see 18+ psi.

If the wastegate actuator has a hole in it, you'll also get high boost, because some of the pressure that should be opening the wastegate is going to bleed off (just as if you had a bleeder valve installed) and the actuator will not be opening the wastegate door fully. This would also result in higher than stock boost.

Ask your mechanic if it's the wastegate actuator that has a hole in it and I think the mystery will be solved.

Moxeys93RX7

what is that manifold off of? i am trying to find a picture of a ported FD wastegate. anyone have one?

jimlab

Yeah, there's one two posts up...

Like I said, that's what a ported wastegate looks like.

RotaryRockeTT

Ok say its the actuator that has the hole in it, now is this a normal thing to see with an actuator having a hole in it? if there was no hole what would the boost be doing?

jimlab

Normal? No, they come without holes, so a hole would be abnormal.

If there are no holes in the body of the actuator, and the actuator rod which connects to the wastegate armature (visible on the left side of the picture above) is not sticking or frozen, then there is a problem elsewhere, probably in the vacuum line(s) which lead to the wastegate actuator.

With a hose connected from the outlet (pressure) side of the front turbo directly to one of the nipples on the wastegate actuator and with the other actuator nipple capped off, the wastegate will open at ~7 psi if it and the actuator are functioning properly.

If there is a hole in one of the vacuum lines to the wastegate actuator, or one has popped off, it will not be opening properly, and you'll get maximum boost limited only by the restriction of your intake/exhaust system, as mentioned above. You could also have a damaged solenoid (beneath the intake manifold).

Here's a picture of the turbo assembly showing the position of the wastegate, actuator, and vacuum hoses.



Here's a scan of a Mazda chart showing the locations of all the vacuum lines which control the turbo system, and the actuators involved.

http://www.rx7turboturbo.com/robrobi...ages/hoses.gif

Hope that helps.

RotaryRockeTT

Ok now you guys think that something is wrong with the waste gate actuator rod correct, it could be sticking, so is that why when i stomp on the pedal my boost shoots past 10 psi? I will also let you guys know that I have a free flowing exhaust system. I have a downpipe, midpipe and well you can say a custom catback its not of any high performance aftermarket but it has a 2.5 inch piping that connects to the midpipe. Now these boost spikes I am getting could be a result of this exhaust system not so the actuator rod.

happyham

yes, your free flowing exhaust is probably why you are getting boost creep. you posted this before, and i'm warning you again, your risks in blowing your engine is running very high.. or maybe i'm just being too cautious.