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Discussion Starter #1
I recently installed a MadDad twin dump down pipe on my 9-2x. I know from dealing with other turbos that sometimes a free flowing dp will change the basic setting on the wastegate, this seems like it would be especially true in the case when I replaced a dead end with a dedicated tube.

Should I disconnect the boost soleniod and test the boost level? (Where is the solenoid)

What should the base boost be set at?

Thanks,

Chad
 

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If your'e posting on a wrx board, I assume that the 9-2X has the has the basic same setup as a wrx. Then the answer is no. A dp is a plug and play install. The ECU will control the boost, and learn to deal with the new dp, just fine.

Are you running EM or an MBC? how are you going to change boost?
 

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Discussion Starter #3
I'm not talking about adjusting the max, rather the basic boost or preload on the wastegate. Less preload can mean that the wastegate will open quicker and boost will rise slower. Because there is less back pressure on the wastegate, I'm wondering is the current setting in now less then the factory base setting. If that's the case I need to increase the preload on the wastegate. This has nothing to do with max boost levels unless you adjusted the wastegate beyond the computer controlled max (which probably isn't physically possible without helper springs)
 

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There are threads describing adjustment of the wastegate arm anywhere from one to three turns (shorter). Apparently, this was first suggested as a way to reduce/eliminate the "flutter" that can accompany a DP installation, but people found it to be effective at restoring "lost" boost.
It sounded to me like a safe, easy adjustment, and that it worked well for a significant number of people.
 

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Discussion Starter #6
The responses I found were interesting, my understanding of the way the turbo system works is the ecu uses the soleniod to keep the amount of boost the wastegate actuator sees either above or below it's setting (base boost) in order to increase or decrease boost levels based on a the target settings. But if it works that way, it doesn't make sense that people would see higher boost levels (other then maybe a quick spike) then the target unless the wastegate actuator was adjusted beyond the max target level.

Does anybody know what the normal boost level with the boost soleniod detached should be?
 

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The boost solenoid is just like an electronic boost controller that is run by the computer. I do not know how much boost it would make by disc. the solenoid as it only reduces boost at certain points. I am pretty sure that actuator spring with no signal should make about 7-8 psi. ?? Do not know if this helps?

PS> The car he has is a WRX that is liscensed to be renamed.
 

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In response to your other question. I think you would have to see the boost curve before and after to adjustthe wastegate with any kind of accuracy, but this would difficult as the computer is going to regulate the curve as it sees fit? You would have to be able to monitor the duty cycle of the boost solenoid to know how to make the adjustment??
 

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Chad W said:
The responses I found were interesting, my understanding of the way the turbo system works is the ecu uses the soleniod to keep the amount of boost the wastegate actuator sees either above or below it's setting (base boost) in order to increase or decrease boost levels based on a the target settings. But if it works that way, it doesn't make sense that people would see higher boost levels (other then maybe a quick spike) then the target unless the wastegate actuator was adjusted beyond the max target level.

Does anybody know what the normal boost level with the boost soleniod detached should be?
While we are theorizing let me throw this out, in the hope that someone who actually knows something will pipe in. :rotfl:

I always took the solenoid to be a pressure/voltage transducer. The ECU doesn't know anything about pressure, it's just a chip. The WG doesn't know anything about voltage, it's a pressure device. The solenoid has to do the translation. It has to be the focus of a feedback loop between the WG and the ECU. Essentially an EBC, like you said.

If you buy that then, if the WG arm is too loose then it is impossible for it to reach target boost. If it is too tight then it sees a pressure over the target boost (the spike). It tells the ecu to correct, and you get a quick drop. In this scenario, it is impossible to maintain a boost higher than target boost, but adjustment of the WG can increase boost, but only up to the target value. This at least explains what people see.
 

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Without engine mgt- opening the exhaust up will likley cause a "overboost"- this is exhibited a quick spike over the oe 13.9ish psi boost achieve(-mine would hit as high as 15.5 in a 3rd gear pull) this is followed by a quick pull back- lower than 13.9, w/ yet another spike (not as high) and then a "normal" gradual decline in boost. It's not the best looking boost curve.

Engine mgt allows one to set a higher boost achieve (normallly around 16ish psi on the oe turbo) and gets rid of the peaks/valleys- to make a much more efficient curve.

Most folks that I have seen adjusting the wastegate were doing so as they wer not achieving the new boost achieve allowed by engine mgt, tightening the waste gate allowed them to see the new boost they were supposed to see. Other tuners use different variations on the 3/16th connector to do the same.

Tightening your waste gate arm would only further exsaperate the double peak boost curve IMO.

What is your boost gauge showing after the install?

Big Sky
 

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If I am not mistaken, the computer uses the MAP sensor to give the computer a voltage translation of boost, the solenoid is only the means to control it. The actuator will work with out the solenoid, its just the computers way of being able to control the amount of boost seen at different RPM's and load values?
 

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Discussion Starter #12 (Edited)
I had done the 3/16's mod and I was getting some spiking but not bad, say to just under 15lbs. After the exhaust I was getting 16.5 spikes, but I had an awful roller coaster boost curve. I removed the 3/16 and now my boost hits 13.5 and prettty much stays there until it begins to taper towards the end of the rpm's.

My reasoning for thinking that a may need to shorten the arm is that the shorter the arm is the more preload there is on the wastegate to keep it closed. Original with the brick wall oem dp, the wastegate would have significant back pressure behind it, now it doesn't. It's possible that the oem setting on the wastegate would be too low without that back pressure (wastegate opening early) and I would be getting slower boost as a result.

Ultimately I'm just going to have to try it and find out. (or be responsible, wait till I get all of my hardware together, and not play with anything until I have on a dyno, but come on...)
 

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I'd say if your boost is hitting 13.5ish in relatively short order (3000 rpms in 3rd gear) and not spiking- I'd leave it alone. If you get engine mgt down the road and they up boost achieve and your not reaching it, then I'd look to the waste gate arm.

Big Sky
 

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What you are saying makes sense...It's just hard for me to swallow all this spikning/fluctuation/creep occurred just with a dp install. Ultimately, the only thing to do is either live with it or give it a go. My only issues with a dp/up install were high EGTS's I would push 1600 F on the highway, which scared me. I would do engine managment and don't push too hard, too long until you do. I assume you have the same ECU and the same issues we have with it in the MY04 WRX's.
 

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Opening up the exhaust allows the system to make more boost than was intended ( oe boost achieve is set at ~ 13.9 psi). Opening up the exhaust lets boost overshoot the 13.9 target- the ecu "reins' it in resulting in a spike, it lets go of the "reins" and it overshoots it again (usually not as much the 2nd time), "reins' it in again and by this time it is usually in it's normal taper down. With an open exhaust and no engine mgt you see a /^^\ looking curve vs a normal /<caron><caron><caron><caron><caron><caron>\. Engine mgt allows one to "dial in" a higher boost achieve taking advantage of the system new ability to make more boost and smooths out the boost curve (among many other things).

The open to closed loop delay in 04+ models is a whole 'nother matter, but one that folks definitely need to be made aware of. Not fun to be running lean at/near full boost :(. This is problem for even stock vehicles.

Big Sky
 

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Discussion Starter #16
What VW is describing is my other concern....right now I can make full boost by just under 2.5k rpm...now this isn't really an issue in gears 1 through 3 because it's so quick, but in 4th or 5th gear, especially 5th....if your cruising at under 2.5 and then punch it, you are gettting to full boost, now your car slowly sweeps through to 3k, all the while staying stoich until (correct?) so basically you've got full boost and 14.7 a/f for more then a few seconds, not good. Like big sky said, this may be an issue on stock rides, because in fifth you can get some decent boost under 3k rpms.
 

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Exactly^^^^ Evidently this was all done to appease EPA evidently (long, long thread @ nasioc, but one worth readin if your in a 04+). Ecutek "simply" (it was actually not simple at all) reverts the crossover back to the 02/03 style- w/ no delay.

Big Sky
 

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Chad W said:
if your cruising at under 2.5 and then punch it, you are gettting to full boost, now your car slowly sweeps through to 3k, all the while staying stoich until (correct?) so basically you've got full boost and 14.7 a/f for more then a few seconds, not good.
Yes. The highway and steep hills were the problems. It wasn't dramatic though. In fifth on the highway I would just reach for a little more to pass, and I could watch the EGT's climbing. I just dropped to 4th more often than I do now. Low gears were never a problem, push the car and have fun, but be careful on the highway.


It's the OL/CL thing, but it was more.I ran for a while with a fully open exhaust. It wasn't just a delay thing, It was always on the lean side. The EGT's were consistently 50-100 higher than cobb stage 2, across the board. I just came to believe that the MY04 ECU is really touchy about exhaust mods, and they are beyond it's capability to learn to adjust fueling.
 

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First it was making the rear O2 sensor more CEL happy, then the OL/CL delay We still don't know the details of what they did to satisfy the EPA, but it is not mod friendly. The solution is simple though, EM.
 
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