04-10-2007, 01:56 PM | #1 |
Intake
Join Date: Dec 2004
Location: Idaho
Posts: 32
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wont hold boost
I have a 1991 Supra Turbo. I've got all the upgrades including lexus afm, stage 3 ct-26, manual boost controller, custom exhaust,mhg,550 inj,custom fuel pressure reg,greddy blow off valve and walbro fuel pump. I noticed when I took it to the track this weekend that it would not hold boost when I would first launch it would go to 15 then drop to 11. So after the first run I turned the boost up a full turn which is equal to 4 psi. Ran down the track agian and the same thing 15 to 11. So the next run I turn the boost up again and again the same thing 15 to 11. So I checked all my hoses, vaccum lines and even check the boost controller and I cant find anything wrong. Its not smoking at all and idles good. Anybody have a clue as to what is going on? Thanks for any suggestions cause I'm stumped.
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04-10-2007, 07:54 PM | #2 |
500whp yet?
Join Date: Jun 2005
Location: CT U.S.A.
Posts: 966
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i think you missed a line somewhere . even a little tiny hose on the opposite side of the engine will cause this boost leak
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300+ RW HP Dyno run, jdm,mod turbo,3"exh,electfan,greddyboost Blown HeadGasket info My Supra KiXGaS |
04-11-2007, 02:08 AM | #3 |
12psi boost
Join Date: Jun 2006
Location: salem mass
Posts: 329
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u only run 4psi thru ur car? u said i turned it all the way up which is equal to 4 pai. 4lbs in a set up like that?
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nothing but the best -mods- so far K&N intake fipk 3" megan downpipe 3"turbo elbow 4 washers on the wastegate highflow cat short shifter 89+ front bumper, pic soon to come many more upgrades soon |
04-11-2007, 02:39 AM | #4 |
12psi boost
Join Date: Mar 2007
Location: Sacramento, Ca
Posts: 373
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he said he turned it up a full turn, not all the way up.. a full turn seems to be equal to 4 psi.
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04-11-2007, 05:30 AM | #5 |
500whp yet?
Join Date: Nov 2005
Location: Mechanicsville, MD, US of A, 20659
Posts: 1,060
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what i would do is with the car running, open the hood and either have someone rev it, or you can do it yourself with the throttle linkage, and rev it till it boost and listen for a leak. if you cant hear one then find the vacuum line diagram on the tsrm and check all the lines. let us know hoow it goes.
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88 N/A w/ 5spd - stock - not running, bhg 87 turbo/targa w/ 5spd- fidanza light weight flywheel, new oem slave cylinder, apexi air filter, no ac and no heat |
04-11-2007, 06:24 PM | #6 |
Intake
Join Date: Dec 2004
Location: Idaho
Posts: 32
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Thanks I'll check it this weekend and let you know.
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04-11-2007, 07:20 PM | #7 |
500whp yet?
Join Date: Nov 2005
Location: Mechanicsville, MD, US of A, 20659
Posts: 1,060
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ill go ahead and post the vacuum diagram for you so you dont need to waste time looking for it, plus the more im on here the less i have to do homework here ya go. taken from http://http://www.cygnusx1.net/Supra...cuum_hose.aspx
that has all the other vacuum diagrams too (cruise control, heater, etc.)
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88 N/A w/ 5spd - stock - not running, bhg 87 turbo/targa w/ 5spd- fidanza light weight flywheel, new oem slave cylinder, apexi air filter, no ac and no heat |
04-16-2007, 03:00 PM | #8 |
Intake
Join Date: Dec 2004
Location: Idaho
Posts: 32
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Well I looked for a vacuum leak. Still cant find one. So when I started it to take a test drive I found that I had an exhaust leak from directly behind the turbo so I tightened it down and took it for a run. It got to 18 then dropped to 14. So Im going to replace the gasket and see if that cures the problem.
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04-17-2007, 12:18 AM | #9 |
3" Exhaust
Join Date: Jul 2006
Location: connecticut
Posts: 92
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let me know if that cures the problem cause i have the same problem i tightened mine up and it still leaks so let me know
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04-17-2007, 04:30 AM | #10 |
12psi boost
Join Date: Jan 2007
Location: long beach, CA
Posts: 252
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i've read
well i was reading i think either importuner and they tested a evo 8 and it lost as it got closer to redline heres the line from import tuner
((showed boost to climb to a peak 20.6 psi as it quickly tapered off at 6000rpm to 16psi then fell flat on its face to a mere 13psi at 7000rpm. )) http://www.importtuner.com/tech/powe...ontroller.html thats the website so the boost drop might be normal..but i could be completely wrong
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