North American Turbocoupe Organization



Low boost
Shelbycobra Offline
Junior Member
#1
Hello,
I’m new to the group.  I just bought an 88 TC and it’s not producing much boost and we think it may be the wastegate.  I have not been able to find parts and I was hoping for some recommendations.
Thanks!
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Kuch Offline
Senior Member
#2
Shelby,
welcome to the group, you will find a lot of great help on here, as I did. My 88 TC had a similar issue when I got it, and it was the wastegate, but not how you think. To trouble shoot, I put it up on ramps, hooked an air line to the wastegate input and turned my compressor regulator down to 15 psi. I then applied the low air pressure to the wastegate to watch the movement, it did not move. At first I thought it was a bad diaphragm and as I went to remove it I found that the control arm itself was kind if semi welded to the wastegate puck arm and holding it semi open. This was basically building slow and low boost. I am not sure why it was stuck so solid together like that, but it was. Once I got it broken apart and moving freely, went right to 18 fast psi with a Gillis. You should put yours on ramps and try watching the movement of the gate.
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4 50 trim, ported E6, 255LPH, BBK AFPR, 3" DP dual 2.5" w Hooker Maxflows, MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
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Shelbycobra Offline
Junior Member
#3
(07-30-2020, 07:51 PM)Kuch Wrote: Shelby,
welcome to the group, you will find a lot of great help on here, as I did. My 88 TC had a similar issue when I got it, and it was the wastegate, but not how you think. To trouble shoot, I put it up on ramps, hooked an air line to the wastegate input and turned my compressor regulator down to 15 psi. I then applied the low air pressure to the wastegate to watch the movement, it did not move. At first I thought it was a bad diaphragm and as I went to remove it I found that the control arm itself was kind if semi welded to the wastegate puck arm and holding it semi open. This was basically building slow and low boost. I am not sure why it was stuck so solid together like that, but it was. Once I got it broken apart and moving freely, went right to 18 fast psi with a Gillis. You should put yours on ramps and try watching the movement of the gate.
Thanks for the reply Kuch, I appreciate any help we can get!  We tried putting a little bracelet like chain around the wastegate to try to hold it shut and it broke the little chain so we know the gate is moving.  We then put zip ties around the gate and we got boost up to 10.  Do you think that means the actuator is shot?  We will have to try your suggestion to see what it does.
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Kuch Offline
Senior Member
#4
I would try it with air pressure to see how it moves. Using air pressure simulates the actual way it operates, so you should be able to see it move as well as look for leaks in the diaphragm. If you have one of those small vacuum pumps you could also try a small vacuum on the diaphragm and see if it holds. You could also try disconnecting the air line coming from the turbo and drive it like that, the boost should build to max what the turbo can put out, so drive carefully like that. with it disconnected, you are letting it build its max pressure regadless of the wastegate actuator. Let us know what you find next.
1988 Turbo Coupe, Black/Black, 5 Speed, Moonroof,  T3/T4 50 trim, ported E6, 255LPH, BBK AFPR, 3" DP dual 2.5" w Hooker Maxflows, MGW shifter, K&N, Gillis valve, RR cam
1964 Ford Galaxie 500XL, 390 6V, 4 Speed, Vast and fast
1960 Ford Starliner, 292 Y Block, 3 Speed, slow and low
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