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WAYY too much boost, how to test a WG?


MusPuppis

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Ok, I think our wastegate is toast folks. (in the Festiva). Today during some extended test runs we really got to see what it would do.. and what it did was boost to 22psi. That = explosion. We did a couple extra runs, more carefully and the boost will climb to 15psi or so somewhat slowly (I would consider it a little too slow but being unfamiliar with the car and this setup I'm not complaining.. yet, lol) but anyway, it hits 15-16psi which is what its supposed to run at, then all of a sudden BOOM. It FLIES up to 20+ and it does it quick.

 

We have a manual boost controller I hooked up today and turned the boost all the way down.. Nothing, no change. Turned it up, no change. Nothing we do is effecting the boost, which leads me to beleive the wastegate has eatin it. It worked when we pulled the Capri motor out but I think at some point it died.

 

How do you go about testing a Wastegate to see if its done? I swear I searched, lol.

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Thanks for the info and link guys. I'll get to it tomarrow and use some shop air. I'll cut the PSI down to around 15 or so before I do.

 

I dont think its a boost controller issue. The boost is WAY too high to begin with. The B6T boosts 7psi stock, and thats what it was running at when it came out of the Capri, we confirmed it in our test drives before the motor was pulled. Nothing was changed that should cause it to boost like it is unless somewhere during our test fits, placement and weirdness it was damaged, which is a real possibility. The FPR regulator didnt make it, haha.

 

I'll look it over as best as I'm able and see what we're looking at. If the WG inside the turbo is pooped out on us it'll give us an excuse to have the turbo rebuilt and ported a little bit, haha.

 

Edit, where should I take the Wastegate feed from? I have it coming from a nipple just before the throttle body.

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Ok.

 

Update,

 

We pulled everything off and got to the actuator, we applied shop air to the tune of 18psi and the actuator arm moves freely and easily, I checked that it was connected to the wastegate itself and it is. So what I did was replace the line, cap the original source and tap in to a boost/vac source from the intake itself, right next to where the boost gauge takes its reading. I see no reason why this should help, but *shrug* the Wastegate seems to be opening just fine, so we'll see.

 

We're putting everything back together now to see if that fixed the problem. To get to the actuator arm in this car we have to rip off the I/C, Rad and a whole lot of junk in the way.

 

So, by way of trouble shooting, if you all were in my position, what would be your next guess, where would you go from here assuming we still boost too high? Oh, I also applied pressure to the actuator and held it to see if it would maintain and it did, doesnt seem to be leaking off at all. Oh, I also removed the MBC completely. Running stock we should boost to 7psi. Maybe a little higher since we have have larger DP and are runnig it wide open. Still though, not 20+ ha.

 

Ill report back as soon as we road test it.

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Thumper,

 

I dont think its an issue of it not flowing enough.. The motor boosts to 7psi stock, and we confirmed this before we pulled it all out of the donor car. The only thing thats been changed since we yoinked it out of the Capri has been the addition of a larger downp pipe.. It worked fine before, now its not at all! well, we've added 2.25 I/C piping as well, but I cant imagine that having an effect.

 

I dont know what the hell is going on, but the car is boosting like a maniac and 20psi is going to eat it alive quickly. On a side note.. 20psi in 3rd gear will break the tires loose.. OMG its fun..

 

Where do you all recommend taking the WG feed from? I used a random extra nipple off the intake plenum, right next to where the boost guage feeds from.

 

I honestly dont know whats going on, this doesnt make any sense and no one else thats done this swap is having any trouble.. Something is up, just dunno what that is. I'm gonna pull the DP off and have a look at the WG itself and see if its moving with the actuator arm,, Maybe something internal is broken.

 

Any suggestions guys?

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So you tested it after removing the MBC and it still overboosts? Is your boost gauge signal taken from the same point as the wastegate signal?

 

Normally I would plumb the WG signal right to the intake plenum, but it really shouldnt matter that much in terms of overboost. If you put it at the plenum, it will take all losses (e.g. IC pressure drop, piping losses, etc.) and open the WG based on the pressure the motor actually sees, not a higher pressure closer to the turbocharger. In other words, your WG will open sooner the closer the signal is to the turbo.

 

I would make sure you test it with no boost controller, and make sure that the vac/boost signal going to the WG is working (use a gauge).

 

Does your new downpipe attach directly to the turbine outlet, or is there some kind of OEM elbow (j-pipe) in between? Could be your new downpipe is preventing the WG flap from opening.

 

 

 

- Greg -

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Yup, it overboosted before the MBC, when I had it installed and still does it once I removed it. The downpipe attachs directly to the turbo, I'll pull it off and check for clearance issues today, thing is the actuator arm is able to move freely and the WG linkage the arm attachs to on the outside of the housing moves freely as well, the DP wasnt allowing the WG to open due to an obstruction wouldnt that lock the linkage up?

 

Yup, we're taking the signal from a nipple right next to the boost controller and we've actually tried taking the signal from the exact nipple the boost controller is hooked on to, no success.

 

I think I'm also gonna try and test the full range of the WG linkage.. Maybe the actuator is working but not extending fully?

 

Im starting to get confused here, it acts so oddly.. We boost to 15 a little on the slow side then from 15 to 20 its FAST, and at 20 we let off, but I'm pretty sure it'll just keep climbing until something breaks.

 

More diagnosis and I'll report back.

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If it's semi-easily reached, drop the downpipe so you can see the turbine outlet and WG flap. Then put your compressed air on the wastegate and verify that it opens.

 

Maybe your WG flap linkage is broken so it looks like it's rotating but really it's just spinning without opening the flap...

 

 

 

- Greg -

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