Damn you cheap Grainger MBC! Boost spiking is holding me back (Grainger users help?)

[Guest bastaad525]

Long post alert

 

Today, for the first time since doing the turbo swap, I have finally heard it ping...

 

I think

 

I had decided that I was going to turn the boost up a bit to 14psi, after seeing lots of guys run that on the stock T3 and having it last months if not years. So figuring the turbo would put up with that w/o going to it's grave TOO early, and knowing I should be able to get enough fuel out of the RRFPR, I turned it up.

 

First thing I notice, is the boost is spiking even more than it was before, getting up to just over 16psi when it first kicks in. Second thing I notice, after getting on it a couple times and watching it spike like that, is that faint 'marbles in a can' sound of (what I think was) detonation, just a few ticks of it while the boost was so high, after it settled to 14psi I didn't hear a thing.

 

I'm actually really surprised... when I dynoed, the w/b O2 showed me going way rich, 10:1, when boost first hit, and staying rich up to about 4000rpm. In my testing this morning I was always flooring it at about 3000rpm, so I would figure I'd have plenty of fuel even to cover that 16psi spike, even if I didn't add any more fuel to cover it (which I did turn it up a bit and by simple nature of raising the boost the RRFPR probably added even more). Maybe that extra boost on the RRFPR is making it run even MORE rich and making me misfire, as I had talked about in a thread I posted a couple weeks ago... but this time it really sounded like ping.

 

So... I'm in a spot here. I would love if I could somehow work this Grainger valve to get rid of the spike... someone suggested running a softer spring, and I'm going to try to find one of the right size. But if that doesn't work, I'm stumped. I'm considering getting a 'real' boost controller, like the Profec B, but of course, as always, money is an issue.

 

I KNOW I could run 14psi safely with the RRFPR, if I could just get rid of any spiking, and it's buggin the crap out of me.

 

Well, if anyone has any other ideas besides the spring thing, ways of cutting the spike out... odd thing is, though I made this one myself, it's the exact same controller that was being sold at http://www.dawesdevices.com, and in their advertisements they claim this thing shouldn't spike at all... so either they're lieing or I did something wrong. And yeah, I did drill the .020" hole in the outlet.

 

OR if you guys could maybe recommend any other boost controllers that work really well and might be cheaper than the pricey Profec B? I don't need any fancy features like scramble boost or any of that... just as little lag as possible and as little spike as possible.

 

OR I'm also wondering if a bleed-type controller would have less spike? I do have one of the bleed type controllers from MSA around, I would think it would spike less, since it doesn't completely block off the boost signal like the grainger valve does. So the WG should open sooner = less spike. What do you guys think?

[Tim240z]

Ehhh fuggettaboudit....drop in a SBC and be done wid it!

[Guest bastaad525]

Tim leeme alone!!!! :D

 

I got two words for you.... BUSH.... INGS!!!

 

But seriously though, whether I keep or sell this car/motor, it NEEDS a better method for boost control... this spiking is just too much.

 

Checking out Ebay now... Profec B's are still pricey as ever

 

Lots of cheap ball and spring boost controllers going for $10-20... wonder if any of them work better than what I got now??

[Tim240z]

Two words for you:

Vee Eight!!

Just ribbin ya!

As soon as my Garage is done (couple of weeks), pull in.....

[Guest bastaad525]

Two words for you:

Vee Eight!!

Just ribbin ya!

As soon as my Garage is done (couple of weeks)' date=' pull in.....[/quote']

 

 

I thought it was as soon as the truck was done? Eh but you know me... in no big hurry, money always tight, and anyways I never want to 'bug' you about it, so YOU let ME know!

 

Tim you should check out Flash's pic album, he uploaded pics of the two Z's there... well... mostly the G nose one, only one pic of the rear (nice tail light conversion) and interior of the Scarab one... sucks that he didn't concentrate more on the scarab since that's the one I'm much more interested in..... Tail lights look sweet anyways!

[cygnusx1]

Put the grainger valve as close as you can to the turbo and the actuator. Use a longer spring and smaller ball so the ball has more room to "get out of the way" and let the pressure get to the actuator more quickly. Put a short little stick ( I used a shiskebob stick ) inside the spring as a limiter so that the ball can't "top out" and restrict the passage of air. I get NO spike with my grainger valve even at 14 psi with a bigger turbo.

[Guest bastaad525]

Cygnus - Thanks for all the tips. I'm not really clear on two things though, what effect would the longer spring have? Mine is already pretty long, long enough that, when I'm assembling the two halves, the ball is already sealed before I even start to screw them together.

 

And the other, I'm not sure exactly what you mean about keeping the ball from 'topping out'. I understand that you mean only letting the ball open so much, but how would opening TOO much restrict air? You mean if the spring coils compress so as to be touching each other that would restrict the air going out of the other side?

 

By the way, I have tried using different lengths of hose, positioning the controller closer to or farther away from the wastegate actuator, and didn't see any difference in the amount of spike

 

Another thing I did try, was stretching my spring a bit. This did seem to lessen the spiking, though of course I had to loosen the housing quite a bit to get back down to the boost level I wanted... saw 20psi once there!! OOPS!

[Bernardd]

Go to the hardware store and pick up a turn buckle. Have it welded onto the actuator. Turn the turnbuckle until desired boost level is reached. Or add a spring to the actuator to increase the tension (easiest). I've done both and have no boost spike. I also have a mbc like you have sitting on the bench. That way it doesn't cause any spikes.

 

AFR's are only half (or less) the cause of knock. Timing and octane are more critical IMO. I realize you can't tune every load point, so you have to compromise at one end or the other.

[Z-Gad]

Where is your boost referenced? If it is off of the turbo, then try referencing it from the manifold or vise versa.

[Thumper]

I noticed less of a spike when I put the boost reference off of the intake manifold. It also compinsates for the psi lost over the intercooler. What this does is instead of the boost controller trying to keep the wastegate at 16psi (which is 14psi after the intercooler), it will keep the wastegate at 14psi which is 14 at the intake manifold. So lets say you took the boost controller off of the turbo and put it on the manifold and you didn't touch the settings. You would then be running higher boost. The longer spring inside the boost controller will make it be weaker so that the difference between 12-14 psi will move the spring further in so that more air can get to the wastgate so it will move further. Basically making the wastegate more sensitive to excess boost. I have done all these mods on my z and still had a slight spike 19psi down to 17psi. But at first it was 18psi spike down to 15psi. I just installed a greddy profec B-spec I and boost response has been greatly improved, no spiking, and way less drop off. So if possible get an EBC. I would recommend a new greddy profec-B type S. Very easy to use and great response.

[Guest bastaad525]

I was gonna ask that same question of Cygnus...

 

Cygnus - where do you get your boost signal from, turbo body or intake manifold?

 

I have tried both... I get much more consistent boost levels if I get the signal from the manifold, and I get about the same amount of spiking either way I run it. MAAAAAAYBE a little less spiking getting the signal from the turbo but not very much difference, I actually just tried that a few days ago. I think the only reason it made a difference at all is because with that setup the MBC was much closer to the WG actuator, whereas until just now, when I ran it off the manifold the MBC was up top, with about 9-12" of hose between it and the WGA.

 

I have been considering changing the wastegate spring or doing that threaded wastegate actuator rod trick in lieu of using the MBC. Isn't the actuator a b***h to get open to change the spring though? I'd have done the threaded rod but I dont have any of those kinds of tools for threading stuff. Today just for the heck of it I took the boost controller out of the equation, just to see if getting the signal from the manifold WAS playing a big role in the spiking... turns out it's not. With the MBC removed, and signal going straight from the intake manifold to the WG actuator, spiking ceased COMPLETELY, and of course, boost levels were back to the stock 6.5 psi.

 

Seeing that made me think the threaded rod trick would be perfect.... I need to find someone with the threading tools....

 

 

ANYWAYS - okay so I went ahead and tried ONE of your suggestions Cygnus since it only took a couple mins. I cut some different length hoses to reposition the MBC very close to the WG actuator... it now only has about a 1/2" of hose between the outlet of the MBC and the inlet of the WGA... it's literally hanging right off the thing.

 

Took it out for a drive and, unfortunately, it didn't seem to make much of a difference Maybe a little bit like .5 psi? It would spike to around 14psi before settling on around 12.5. So I guess a little better, before it was getting closer to 15. I'll try to track down a smaller ball and softer spring soon.

 

 

Bernardd - my timing is 2* advanced from stock (22* BTDC at idle) and I'm on crappy 91 octane. If it came down to it, I would rather lower boost and lose the power than retard timing and lose a VERY noticeable amount of off boost torque and throttle response. Because of course I do a lot more off boost driving . Even the 2* advance made a very big difference. Eventually I'd love to get a MSD boost retard so I could advance my off boost timing even more and cut on boost timing enough to get away with more boost. But man... at 10:1 afr (or even richer, on the dyno it actually 'spiked/dipped' into the mid 9's when boost first hit!) I would think that'd be rich enough to handle even the brief spike of 16psi

 

 

EDIT: just missed Thumper's post...

 

Yeah I have noticed that too, how the boost will behave differently if I run it off the turbo. W/o changing the settings, the INITIAL boost level will actually be the same, but as RPM's increase, pressure drop across the I/C increases as well, so boost will fall off as RPM's go up, when I get the signal from the turbo. This is what killed my last dyno session When I run the signal from the manifold, boost stays more or less the same all the way to redline.

[cygnusx1]

I reference my Grainger valve from the compressor housing about 2" back from the outlet. Thumper, you explained my longer spring idea correctly. I should have said longer, softer spring. Yes Bast, in my case I use a T body for the grainger valve. If the ball opens up to the level of the outlet leg of the T, it could block some flow or become a restriction. In summary, just be aware of where the ball can go inside the valve body so that it doesnt block any flow in the open position.

 

EDIT Sometimes it's too easy to overlook the obvious....is your actuator free to move freely and is the diaphram in perfect working order. Actuator rod alignment...etc.

[Bernardd]

Take off your actuator or get another stock one from the JY. Take it to a hardware store and match up a turnbuckle with a similar size rod. Take it to a machine shop and have the loop on the end of the actuator cut off the stock rod. Cut off the loop at the end of the turnbuckle rod. Weld the actuator loop to rod you cut off of the buckle. Weld the other end of the buckle (again, cut off the loop at the end) to the stock rod. Make it the same length as the stock rod was with the buckle threaded close to all the way out. That way you can adjust from stock psi to bust a hole in the block psi.

 

I added a spring to the gate by drilling a hole in the actuator mounting plate and placeing one end in the hole and the other thru the hole for the retainer on the wastegate swingvalve (keeps the stock rod from jumping off the rod) That's the easiest to do but you need a bunch of springs to set the boost to what you want.

[Guest bastaad525]

I reference my Grainger valve from the compressor housing about 2" back from the outlet. Thumper' date=' you explained my longer spring idea correctly. I should have said longer, softer spring. Yes Bast, in my case I use a T body for the grainger valve. If the ball opens up to the level of the outlet leg of the T, it could block some flow or become a restriction. In summary, just be aware of where the ball can go inside the valve body so that it doesnt block any flow in the open position.

 

EDIT Sometimes it's too easy to overlook the obvious....is your actuator free to move freely and is the diaphram in perfect working order. Actuator rod alignment...etc.[/quote']

 

It's really odd how much we're differentiating here. I get horribly erratic boost response if I run the boost signal from the compressor housing. It wasn't always like that... when I had no I/C I had NO problems running the signal from the compressor, I had only very minimal spiking at 10psi, and boost stayed constant to redline. After I installed the I/C spiking got worse (probably more due to me turning the boost up) and boost fell off horribly, so I switched the boost reference to the manifold. No one ever was able to explain why I was having those problems.

 

About the actuator working properly, I'm assuming all is working properly there, as I said when I took the MBC out of the equation this morning, everything was working perfectly, turbo spooled quickly to 6.5psi with no spike.

 

Honestly I'd rather not mess with springs for the WG actuator, if only because as Bernardd mentions, it's gonna be trial and error trying to find the right spring/combo of springs to get the boost level exactly where I want it.

 

About this turnbuckle business... okay I'm stumped... I honestly have no idea what a turnbuckle is, so I'm having trouble picturing what you guys are trying to tell me. But I'm assuming this is different than the threaded rod method?

 

Think I'm putting the Profec B on top of my Xmas list but dammit I was really hoping for a WB O2!

[Guest bastaad525]

hey Thumper and Cygnus, where did you find springs and smaller ball bearings for use in the Grainger valve?

[Thumper]

I found some springs at local mom and pop hardware store, sears hardware, home depot, and lowes. Home depot had the one I wanted though. Make sure you bring your mbc inside because a small difference in diameter can make it bind. If you get too long of a spring then your boost will never go low enough even with your mbc unscrewed all the way. So I would by a two one really long and one slightly shorter then return the one you didn't need. Good luck and watch the boost gauge:twisted:

[Sean73]

I don't think you've ruled out the actuator yet. It's possible for the actuator to perform fine for stock boost levels, then get sticky at high boost levels.

 

I had a faulty actuator one time, which I discovered by testing it with my air compressor. It would open partially, then stick for a while, then suddenly jerk open all the way.

 

I think I would try a bleeder type MBC and see how it works. If it still spikes, then turn your attention back to the actuator.

[cygnusx1]

SPRINGS and more SPRINGS....http://www.mcmaster.com I think I am using a stretched out pen spring though. Let me see if I can't find the leftover parts from when I assembled my Grainger valve. I may have enough to build another one and send it to you.

[Guest bastaad525]

SPRINGS and more SPRINGS....www.mcmaster.com[/url'] I think I am using a stretched out pen spring though. Let me see if I can't find the leftover parts from when I assembled my Grainger valve. I may have enough to build another one and send it to you.

 

 

That would be sweet I had some parts leftover too but definately not enough to assemble a whole 'nuther one. actually I only had one part left over because I had to order that particular part in a set of 10. It's just the barbed nozzle end, the inlet side.

 

I was thinking a pen spring as well I know those are VERY soft, I actually checked some of the pens around the house but all the springs were very small in diameter. Well I'm going to try to hit Home Depot over my weekend and see what they have.

 

If I find a spring and that doesn't do it, I'm going to try Seans suggestion and switch over to the bleed type MBC and see what difference it makes. I'll have to buy/make some parts for that as I dont have the barbed hose connections for it nor the mounting bracket. To be honest I'm not even sure how to hook the thing up but I'll look it up I know i"ve seen some directions somewhere.

[EZ-E]

After reading all of this it made me look into my set up. I was running my reference off of the manifold, and I was still using the same old stock wastegate actuator on new turbo just for an ease of set up.

 

Well like I said after reading this I decided that maybe my whole problem was with the stock wastegate. When I had purchased my new turbo from http://www.speedshopthagard.com, it had come with a universal, adjustable wastegate actuator.

 

Well yesterday I had finally taken the time to put it on. Just ran a reference line from the intake manifold to the new actuator.

 

I will say this, boost spike, the bit of lag, though there wasnt much at all was now gone. It also seems that the turbo has a much more profound effect at boost then what it did before.

 

I would think depending on yoru mileage, you may want to look at the actuator as part of your problem. Boost now though holds nicely at 14psi, no spiking and man does it come on hard:)