North American Turbocoupe Organization



factory vac line routing
stefan9 Offline
Junior Member
#1
I have a 1990 Mustang LX that was originally a 4 cylinder automatic that was swapped to a 2.3T and a T5 from a 1988 Turbo Coupe. I purchased the Mustang with the engine, transmission and rear end already swapped. There were a lot of electrical/wiring/ECU problems which I've straightened out. Here is the rundown of what we have now:

- 2.3 Turbo from 88 TC
- EGR deleted and blocked off on the intake manifold
- factory BCS all removed and replaced with Gillis valve
- speed control/cruise control present but not connected

I've had a lot of problems getting the car to idle correctly and I believe it has something to do with the vac setup. I've replaced and tested the TPS, replaced the plugs with NGK TR5s, replaced the wires (MSD), replaced fuel pressure regulator and tested fuel pressure and replaced idle air control valve. The idle hunts and I've noticed driving at low speed it often feels like it wants to stall. I've pulled the EEC codes and the only faults are for the factory electronic boost controller and EGR solenoid which neither are connected or installed.

I've found and studied the Turbo Coupe vac diagram that is floating around the web. I attached the original and a modified copy of what the vac tree looks like right now. Will the car run properly with the current diagram I attached? I'm really looking forward to getting this project vehicle running top notch. I've also ordered the front mounted intercooler from Stinger Performance although it hasn't arrived yet. Thanks.


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Jeff K Offline
Administrator
#2
What brand IAC? The ONLY IAC that works correctly is the Motorcraft one. ALL aftermarket IAC's are junk.
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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stefan9 Offline
Junior Member
#3
Running the "Standard Motor Products AC29" right now. The engine originally had a F0AE-9F715-A2A which I'm guessing by the decade prefix isn't the right part for an 88 TC. I'll order a Motorcraft IAC now.
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anasazi4st Offline
Senior Member
#4
You might not believe this, but....

What kind of gasoline are you running?

I recently changed from QuikTrip to Chevron. Reasons for using QuikTrip—inexpensive, they offer free air, and their stations are everywhere here.

Background: for some time I have been less than pleased with my engine’s performance. Idle is up and down, not steady; fuel performance is lower than historically it’s been; the acceleration doesn’t feel as aggressive as it used to. I’ve been filling up 99.9% of the time with QuikTrip 91 octane Premium since at least 2008.

I checked all the usual suspects; pulled codes, got just an 11 for all test modes.

Well, a couple of weeks ago my TC had clearly had it with that brand of gasoline. It started out with an idle that was unsteady upon startup, going up and down and almost stalling. Then, after a few stops where I shut down and a few minutes later restarted (part of my job involves visits to retail establishments) it DID stall, and would only hold if I accelerated above 1500 or so...eventually it would even out.

Finally, that was it. While I held the pedal down to keep the idle up and prevent stalling, clouds of grey smoke that smelled like burning oil were pouring out of the tailpipes. It has never done that before. Terrified that there was something seriously wrong, I did not shut it down the rest of the day, just allowed it to idle with the doors locked in the various parking lots while I went about my job. When I got home I opened the hood—the PCV valve on top of the valve cover had been blown off, apparently, and oil had splattered all over the top of the engine and the inside of the hood. I replaced it and cleaned up the spilled and splashed oil, restarted it and all seemed good. I figured I got some bad gas.

I changed the fuel filter...and, after some thought I decided to try a fillup of Chevron Premium fuel, as I was down to a half tank. The results were immediate—the idle smoothed out, no dips up and down; there was increased acceleration and smoother power; and the MPG increased by almost 10%. And, there have been no more smoking incidents since.

Based on that I won’t be getting any more QuikTrip gas (although I will admit changing the fuel filter might also have helped).

Just beware of some of the inexpensive so-called “Top Tier” fuel. I looked up (alleged) Top Tier fuel stations in the US, and right there is QuikTrip. I’ll still go there for the free air if I ever need it, but I’m done with the fuel. The same kind of improvements happened by switching to Chevron in my wife’s car (2005 PT Cruiser), but to a lesser extent.

(Why is free air so important? Adding Slime sealant in 1995 to my rims severely pitted the inside sealing bead in each wheel, resulting in low/flat tires every few days. An easy temporary remedy was a near-daily visit to QuikTrip for the free air; recently fixed by a coat of a black sealant added by the tire shop to each when I got new tires a couple of months ago.)
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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Mikey97D Offline
Junior Member
#5
Is it possible the PCV got clogged to cause the problems and not the fuel?

On my old carburated cars I used to see differences in fuel between Shell and Mobile. My car would run like crap on Mobile but ran perfect on Shell.

Was the PCV valve the one from the crank or valve cover? Just curious.

In Connecticut, there is a law the station must provide free air if asked. Some stations have a coin operated machine, but if you go inside and ask they must turn it on for you. An odd law but they may have something similar in other states.
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Mikey97D Offline
Junior Member
#6
stefan9 Wrote:Running the "Standard Motor Products AC29" right now. The engine originally had a F0AE-9F715-A2A which I'm guessing by the decade prefix isn't the right part for an 88 TC. I'll order a Motorcraft IAC now.
What Motorcraft part number did you find and where did you end up ordering it from? My idle is erratic sometimes although I need to adjust the voltage first.
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anasazi4st Offline
Senior Member
#7
It was the valve cover PCV.

I searched for answers here from years back, using PCV as the keyword. Someone else suggested it might be a clogged PCV—the one that rattles—for a similar issue. I checked and replaced it, that wasn’t it.

In 27 years of ownership nothing like that has ever happened. Sure, if you stick the tiny hose from the carb cleaner aerosol can into the connector next to a vacuum line—like the one that goes into the top of the intake manifold—and spray, you’ll get clouds of grey smoke. This did it on its own.
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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Jeff K Offline
Administrator
#8
^^^^ Not sure what you mean by "valve cover PCV"? There is only 1 PCV valve on the 2.3T. It resides in the vertical hose on the driver side valve cover. The lower hose goes to the oil separator, and the upper hose goes to the bottom of the upper intake. It is important to use ONLY the Motorcraft EV127 PCV valve. Aftermarket ones all leak boost into the crankcase.
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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anasazi4st Offline
Senior Member
#9
Searching the Internet leads to some confusion as to exactly where the PCV valve is located—and is there more than one?

The ACTUAL PCV valve is by the distributor (“driver’s side valve cover”), as Jeff mentioned.

However, Ford’s Engine shop manual (page 24-45-3) mentions another PCV part which connects to “the turbocharger air inlet elbow.” It is mounted in a large round rubber grommet on the top rear of the valve cover. This is really more of a filter, as it’s stuffed full of interwoven strands of steel resembling the old kitchen copper scourers I remember as a child. I could not find a name for this part.

This is what I was referring to as the part that had worked loose. Sorry for the confusion.
Another proud dues-paying member.

1987 Turbo Coupe w/T5OD, 8.8 axle, grey smoke; most options. Got it in 1991 with 41K miles: 3 turbos, 2 heater cores, 1 T5OD full rebuild, 5 clutches, 1 head gasket, 2 Teves II ABS units, etc. later....
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firebirdparts Offline
Member
#10
That is the air inlet for positive crankcase ventilation. Air goes in through the brillo pad and out through the PCV valve. Of course, when you have enough blow-by, it might cease to be the air inlet.
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