North American Turbocoupe Organization



WASTEGATE ADVICE NEEDED
87TurboBird2.3 Offline
Junior Member
#1
Hey guys, I just picked up a 1987 Thunderbird Turbo Coupe and I'm needing some help regarding the wastegate. Before I get started, I wanted y'all to know that although I have 32 years of experience turning wrenches and I know my way around a car pretty good, I'm a newbie when it comes to turbos, as this is the first turbo vehicle I have ever owned or worked on in my 50 years on this planet. So the questions I ask may sound stupid to you, but keep in mind to someone who doesn't know this information, it's not a stupid question. So take it easy on me guys....Ok, here goes.

So the previous owner told me that the owner before him modified the turbo and did something to the wastegate so that it doesn't function. I'm not sure if he removed it completely or just made it inoperable and I'm wanting to get it working again. So I have a few stupid questions....

1) Do these cars have internal or external wastegates?
2) Exactly where is the wastegate located?
3) Where does one buy a wastegate for these cars? I can't find anyplace that sells them and I can't find any articles online that specifically talks about these 87 Birds. Do any of you have any parts resources or websites you can share with me?
4) Also, about how much are these cars worth is I was to sell it. It's black and the paint is starting to crack and peel in a few places. Other than that, the car is in decent shape for it's age, but far from perfect. I know this is a vague description and you probably need a lot more details and possibly some pictures to answer this question, but I was just curious if you thought I could get somewhere in the neighborhood of $2000? 

If anyone has any info, tips, or advice they're willing to share about anything on these cars, I'm all ears. Thanks for the help.
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BradM Offline
Junior Member
#2
Welcome. I'm also a long-time wrencher and new to turbos and I started my project last fall. I've learned a lot from this forum. The picture below is the stock turbo (IHI) viewed from the bottom side. IHI's have internal wastegates. The actuator (wastegate actuator or WGA) has a rod connected to the wastegate and controls the wastegate. The wastegate is just a small "door" that gets opened to bleed off exhaust to control how fast the turbo spins, thus controlling boost pressure. The actual wastegate ("door") on this IHI is integrated into the turbine housing. It's a super simple device and would be very low on my list of suspected failure.

If it were me, I would suspect the line controlling the WGA. If the line had no pressure (was not getting a boost signal), the door would not open. Further, the WGA is connected to a servo which the ECU controls (the ECU signals when to supply pressure to open/close the WGA). Finally, someone may have bypassed the servo and installed a manual boost controller. Either way, I'd focus on the WGA its control line.


Attached Files Image(s)
   
1965 Mercury Comet Caliente; 1968 Mercury Monterey; 1969 F100 Ranger; 1987 Thunderbird Turbo Coupe
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BradM Offline
Junior Member
#3
Here's another picture.


Attached Files Image(s)
   
1965 Mercury Comet Caliente; 1968 Mercury Monterey; 1969 F100 Ranger; 1987 Thunderbird Turbo Coupe
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87TurboBird2.3 Offline
Junior Member
#4
(03-07-2021, 02:36 PM)BradM Wrote: Here's another picture.

Brad, thank you for the pictures and the explanation. So I spoke with the guy I bought it from and I confirmed that he told me that if you spin the turbo too high I will hear an over boost alarm. Not sure if that means anything. I'm sure that's just a safety feature built into the car.  

So what you said makes sense. If the wastegate is just a door inside the turbo, it makes sense that the WGA or the line going to it might be where the problem is. That's what I will focus on to start with. More questions....

1) In your picture, is the servo the round thing with the rod coming out of the back side of it and the WGA is the rod itself? 
2) If the servo is controlled by the ecu, that means it's controlled electronically or is there some sort of hose that is connected to it? 
3) If someone installed a manual boost controller, where would that be located? Is it some sort of electronic box that can be mounted anywhere? 

I'll be diving into this thing today, so hopefully I'll find the problem. Heck, I'd be happy if someone just disconnected the rod that goes to the wastegate. That would be an easy fix, but knowing how my luck goes, it won't be that simple...LOL. I'll keep you posted on what I find.
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Jeff K Offline
Administrator
#5
1) Yes, the round thing with the rod coming out of it is the WGA. The rod connects to the WG in the turbo. Factory WGA will start to open around 9 psi boost. If you have an air compressor apply 10 or so psi to the WGA, you should see the rod start to move out of the WGA and start to open the WG on the turbo. DO NOT apply more than 15 or so psi to the WGA as too high a pressure will blow the rubber diaphragm in the WGA. If the rod doesnt move, the WG in the turbo may be rusted shut if the car sat for a long time. You can remove the small C clip where the rod attaches to the level to the WG itself and see if the WG moves freely. BE CAREFUL REMOVING THE C CLIP! They LOVE to fly off and vanish!

2) In the 100% stock setup, Pressure to the WGA is controlled by the EEC IV. With the fuel switch in REGULAR position, full boost pressure is applied to the WG so max boost will be the 9 to 10 psi. With the switch in the PREMIUM position some of the boost pressure the WGA sees is bled off via the BCS (boost control solenoid - the 1.5 or so inch in diameter black thing with 2 vac lines and one 2 pin electrical connector). The BCS is PWM controlled by the EEC IV to bleed off boost the WGA sees to "fool" the system and increase max boost to 14 psi in 1st and 2nd gear only. The BCS is poorly made, and often leaks or fails internally.

3) Most of use get rid of the BCS and use a boost control valve to set max boost to 15+psi in all gears. Google "Gillis Valve" or search here for more info. You can buy electronic boost control systems ($$$), but the Gillis type pressure relief valve is fairly cheap and works very well. It is basically an adjustable pressure relief valve. Boost below set pressure = WGA sees no pressure and doesnt open the WG, and boost above set pressure, valve opens and applies boost pressure to the WGA, opening the WG to limit boost.

About the highest safe boost you can safely run with stock electronics and a boost control valve is 17 psi (Premium fuel ONLY). Anything higher than 17 psi requires more fuel via higher fuel pressure, larger injectors, an aftermarket EEC, etc.
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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87TurboBird2.3 Offline
Junior Member
#6
(03-07-2021, 09:44 PM)Jeff K Wrote: 1) Yes, the round thing with the rod coming out of it is the WGA. The rod connects to the WG in the turbo. Factory WGA will start to open around 9 psi boost. If you have an air compressor apply 10 or so psi to the WGA, you should see the rod start to move out of the WGA and start to open the WG on the turbo. DO NOT apply more than 15 or so psi to the WGA as too high a pressure will blow the rubber diaphragm in the WGA. If the rod doesnt move, the WG in the turbo may be rusted shut if the car sat for a long time. You can remove the small C clip where the rod attaches to the level to the WG itself and see if the WG moves freely. BE CAREFUL REMOVING THE C CLIP! They LOVE to fly off and vanish!

2) In the 100% stock setup, Pressure to the WGA is controlled by the EEC IV. With the fuel switch in REGULAR position, full boost pressure is applied to the WG so max boost will be the 9 to 10 psi. With the switch in the PREMIUM position some of the boost pressure the WGA sees is bled off via the BCS (boost control solenoid - the 1.5 or so inch in diameter  black thing with 2 vac lines and one 2 pin electrical connector). The BCS is PWM controlled by the EEC IV to bleed off boost the WGA sees to "fool" the system and increase max boost to 14 psi in 1st and 2nd gear only.  The BCS is poorly made, and often leaks or fails internally.

3) Most of use get rid of the BCS and use a boost control valve to set max boost to 15+psi in all gears. Google "Gillis Valve" or search here for more info. You can buy electronic boost control systems ($$$), but the Gillis type pressure relief valve is fairly cheap and works very well. It is basically an adjustable pressure relief valve. Boost below set pressure = WGA sees no pressure and doesnt open the WG, and boost above set pressure, valve opens and applies boost pressure to the WGA, opening the WG to limit boost.

About the highest safe boost you can safely run with stock electronics and a boost control valve is 17 psi (Premium fuel ONLY). Anything higher than 17 psi requires more fuel via higher fuel pressure, larger injectors, an aftermarket EEC, etc.

Jeff,

Thanks for that excellent explanation. That helps a lot. 

So I took the intercooler off (I assume that's what it's called; the heater core looking thing that sits on top of the turbo, goes into the intake and mates with the air vents in the hood) and inspected the turbo and everything around it. I didn't see any aftermarket or non-factory parts on the turbo. However, I did see something that might be an aftermarket part that is located in front of the turbo and has a conical shaped air filter & intake tube connected to it. The top of it says "Vane Airflow Meter). Not sure what that thing is. Am I correct to assume it's the same thing as a mass air flow meter like I have on my 92 Mustang GT 5.0??? 

So I will see if I can take the c-clip off the WGA arm and see if I can move the wastegate. It's a son-of-a-gun to get to since it's on the bottom side of the turbo and the suspension is in the way. I do have an air compressor, but I'll have to figure out how to regulate the air pressure so I don't damage the WGA. If the wastegate isn't frozen, then I assume the WGA might not be working. I'll try to apply some air pressure to it and pray I don't damage it.....I did see the BCS. Didn't know what it was until I read your reply, but I did notice it has a couple vacuum lines going to the turbo. 

So if I end up having to replace some parts on this turbo, does anyone know where to purchase these parts? Do local autopart stores (like Autozone, Napa, etc...) carry parts for the turbo or is there a special aftermarket company I would need to go through? Where do you guys buy your turbo parts for these cars? The reason I ask is if I have to take apart the turbo because the wastegate is froze or the WGA needs replaced or whatever else I find, I need to know who sells these parts. 

I'm having to replace the master cylinder/brake system also. I have a used one that came with the car that I was told worked. I noticed this car doesn't have a vacuum brake booster. Is this brake system a hydroboost system? Never seen this style of brake system before? And apparently I'm told you can't buy these brake parts at Autozone or the local parts store, that's why the guy I got the car from got a used one off another car. I'm praying it works. We'll see....
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Mikey97D Offline
Member
#7
Welcome aboard!

Someone mickey moused with my waste gate too before I got the car. They added extra washers or messed with the spring in the actuator. I got a used actuator from Bryan or Ron because I had to cut the actuator rod off the wastegate arm because it was rusted so bad. I did that on the bench. I was able to test the system in the car before with an air regulator to WGA to see it wasn't moving. I don't have a lift and it wasn't going to happen with me laying on the ground.

The Vane Airflow Meter (VAM) goes before the turbo and it is common to remove the air box and just put a conical filter on it.

The TEVES Brake system predates the Hydroboost system. I think we were the test subject with these cars for the hydroboost to come. There's no new parts to be had for the system so used is the only option if something breaks or convert to another system. I think in the FAQs area there is a guide for the vacuum conversion.

I am curious if anyone has a link to a new WGA for sale?
1988 TC, 5 spd, Stinger 3" Exhaust, Schneider Roller Cam, -4° Cam Pulley, Cone Filter, Gilles Boost Control Valve set at 17 psi, [font=medium-content-sans-serif-font, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif]Walbro 255 lph, [/font]CHE Rear Lower and Upper Control Arms, Braided Brake Lines, Hawk HPS 5.0 Front and HPS (F) Rear, CRES Inserts in front calipers, and '93 Cobra Wheels with General 235/50R17 Tires.   
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Jeff K Offline
Administrator
#8
The VAF (Vane Air Flow), also known as the VAM (Vane Air Meter) is a somewhat primitive mechanical version of the electronic MAF (Mass Airflow Sensor) used on all cars from the early 1990s on. The VAF has a door in it that is spring loaded. As more air flows into the engine, the door opens more. The door is connected to a variable resistor whose resistance changes as the door moves. The VAF outputs a voltage via the variable resistor to the EEC so the EEC knows how much air is going into the engine. At idle, VAF outputs a little under 1 volt, and with door fully open, VAF outputs around 4.5 V to the EEC.
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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