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Post by sleepinsol on Sept 26, 2009 20:33:41 GMT -5
well ive been chasing boost problems since i got the car going a few weeks ago. it went from breaking up under boost (bad vam and bpv in backwards), to now holding boost very well, but being very laggy. i dont make full boost (17-18 psi) until after 3000 rpm! if memory serves that should not happen. any one have any thoughts on this one? the setup is basic bolt ons. gillsi valve, kirban fpr, stinger 3" dp (open), bob log, forge bpv, stinger fmic,and a 3" intake arm with a k/n filter. you would think with all the air flow mods it would spool and hit full boost fast without a problem. could it be the huge stinger intercooler with that tiny turbo? or should i look elsewhere for this mystery?
i replaced my vc gasket and while i was at it the tb, upper intake, and egr gasket to chase any pressure leaks on my intake side. im stumpped here. i have also taken care of all the possible vac. leaks with hose clams and made sure all is intact on the tree as well. there do not appear to be any exhaust leaks either.
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Post by Stinger on Sept 27, 2009 2:14:40 GMT -5
Are you sure you have absolutely no exhaust leaks between the head and turbo? A small leak at idle becomes a big leak under boost.
How much vacuum at idle?
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Post by sleepinsol on Sept 27, 2009 11:05:17 GMT -5
that is something i will look into today. ill get the stethoscope out and give a good listen and give everything around there a good tightening. ill also get the vac. gauge on it today so i can get you a number as well.
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Post by sleepinsol on Sept 27, 2009 23:34:11 GMT -5
well the good news is i dont have any exhaust leaks. all the bolts are tight around that area and the stethoscope didnt pick up any cracks. the bad news is im still searching. im going to look at the wastegate tomorrow and see if maybe during the swap we knocked something loose down there by accident.
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Post by Stinger on Sept 27, 2009 23:50:28 GMT -5
Make sure the gate is all the way closed and that it has a little preload on it (1/8" or so is enough).
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Post by sleepinsol on Sept 28, 2009 0:22:44 GMT -5
will post an update tomorrow.
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Post by sleepinsol on Sept 28, 2009 17:04:42 GMT -5
well i got a minute to get under the car today and take a peek at the wastegate. i didnt get a real good look at it, but i got a hand on the arm and it was in there tight, and had a slight wiggle to it (im guessing this was the preload you mentioned). everything was intact down there. i also tightened all my tbolts down again.
tomorrow im going to get out there with a timing light and make sure its set right as well. still chasing the problem though.
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Post by Stinger on Sept 28, 2009 18:35:09 GMT -5
That test didn't really tell you anything. The spring in the wastegate actuator is actually pretty strong so you have to pull it off the lever in order to see the preload and to see if it is closed or not.
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Post by Stinger on Sept 28, 2009 18:35:31 GMT -5
You'll want to check cam timing as well.
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Post by sleepinsol on Sept 28, 2009 23:06:11 GMT -5
yes cam and distributor timing are next on my list. i want to get the car up on a lift to get to that wastegate. its really tight down there. i may even take the down pipe off. like i said it was a quick tetst. more updates asap though. on the good side, when it does hit full boost, it pulls nice and holds well. its just late getting there.
i should also metnion that the vac line coming from the bpv has an adapter in it bc i did not have a long enough line to run all the way to the tree. so the line goes from one size, to a smaller size, and then back to the same bigger size and then connects to the tree. my physics tell me that should not have an effect on how fast the turbo spools, but i could be wrong.
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Post by 93stangnow23t on Sept 28, 2009 23:47:27 GMT -5
That may be your problem stuff like that has happened to my brother he has a turboed motor but diff car so I don't know stinger could probably fill you in on that.
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Post by sleepinsol on Sept 28, 2009 23:57:29 GMT -5
yea he would probably be the one with some insight on it. im taking this one thing at a time and slowly ruling things out. ill find it eventually.
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Post by Stinger on Sept 29, 2009 1:59:53 GMT -5
You can test if the problem is in the boost controller or hose/adapter size by simply removing/plugging the line that goes to the wastegate actuator. This should put it in "overboost" mode but the boost should build as quickly as possible (until the pressure in the exhaust housing pushes the swing valve open).
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Post by sleepinsol on Sept 29, 2009 8:47:43 GMT -5
do i remove the line from the wastegate and then plug the wastegate and the line i pulled off? its basically just running no boost control at all and letting the turbo spin as fast as it possibly can correct?
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Post by Stinger on Sept 29, 2009 11:53:43 GMT -5
Don't have to plug the wastegate, just plug the line going to it so you don't have a vacuum/boost leak.
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