North American Turbocoupe Organization



overboost problem
turbobirdsilver Offline
Member
#1
Ok i searched but nothing came up on this.

Anyway i have a stock 83 Tc 5-speed. Its got a K&N and just had my 3 inch exhaust installed. Now since i got the exhaust installed it spools up faster and pulls harder on the top end. Im getting the overboost buzzer at WOT at 4000-4300. I let off but itas getting frusturating no to be able to wind out the motor. Now i thought he might have screwed up the wastegate rod. But it has no more boost that i can tell. The power increase isnt substantial. The exhaust guy also only mad the down pipe just after the turbo manafold turndown. So its not a full downpipe.

Any suggestions? I was wanting to turn the boost up soon. But if im pushing 18 already im gonna be dissapointed. I know the over boost sensor detects the pressure in the manafold.

Thanks guys. This board is a god send.

Ray
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Pete D Offline
Administrator
#2
Do you have some kind of aftermarket boost controller?? Not sure what the 83 over boost buzzer was set to go off at. I would suggest you get an actual boost gauge in it to find out what it is putting out
Pete Dunham


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karnage Offline
Member
#3
The stock boost buzzer goes off at 17-17.5 psi.It drove me nuts.I just took off the hose to the solenoid.I think its adjustable
by a tiny screw inside the vacuum port.Maybe your actuator hose is pinched.
84 TC with 88 hood LA-3 full 3" exhaust Rods header ported/polished big valve head schneider roller cam RW adj cam gear Kirban gillis at 20 # boost MSD ignition 255 lph Walbro full gauges
17 inch centerlines 944 front mount IC 80mm MAF
65mm tb-rotated intake on the way to 400HP
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Jeff K Offline
Administrator
#4
As Karnage said, a properly operating overboost switch goes off at 17.5 psi. THe switch is, IMO, cheaply made, and they do fail, often going off for no reason, or going off at an incorrect boost pressure. You really need to gat an accurate boost gauge, as Pete suggested.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 23 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 04 Taurus Duratec (wifes car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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martin0660 Offline
Posting Freak
#5
Are you guys sure about the 17.5 psi for the 83? I recently had the opertunity to see what I believe an unmolested 83 TC. on this car, the signal for the wastegate came right off the turbo outlet, no BCS, no bleed, nothing. Assuming its the same wastegate as the later stuff, I ASSumed those were limited to 9.5-10 psi.

Bob Myers

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My 88 Thunderbird TC Pictures, Updated 5-8 with a few drag pics
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karnage Offline
Member
#6
Yeah its 17.5 for the buzzer to go off and yeah the stock boost is 10-12 psi.They figured 17 psi was still safe enough to run if something would happen to the actuator.Just unhook the hose and plug the fitting.
84 TC with 88 hood LA-3 full 3" exhaust Rods header ported/polished big valve head schneider roller cam RW adj cam gear Kirban gillis at 20 # boost MSD ignition 255 lph Walbro full gauges
17 inch centerlines 944 front mount IC 80mm MAF
65mm tb-rotated intake on the way to 400HP
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martin0660 Offline
Posting Freak
#7
So back to the original question, I would say that the only way for it to actually exceed the wastegate spring is to have a leak in the hose from the turbo outlet to the actuator. The leak is working to bleed signal.

Bob Myers

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My 88 Thunderbird TC Pictures, Updated 5-8 with a few drag pics
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