Hello. First off, let me specify that my car is a 1984 Thunderbird Turbo Coupe, and not a Mustang. I'm just hoping that someone on here can give me some insight as to where to look next for the solution to my trouble. The best way that I can come up with to describe my condition is to just list the facts:
The engine will start right up and idle, maybe slightly erratically but decently enough not to concern me. It revs up fine in neutral.
When I try to accelerate in any gear, the engine takes off fine until about 3000 RPM, right as the green "boost" light is coming on and you just start to hear the turbo spool up. As soon as the light comes on, the engine will not accelerate any further, unless you let off the throttle and feather the gas slowly. In other words, if you try to floor it, it immediately loses all acceleration, and feels like a rev limiter is being bounced off of.
Yesterday, I installed new plugs (autolite copper, gapped to .32) and wires (msd 8.5mm, given to me) and went for a spin around the block. About 3 minutes into the trip, the car just died and wouldn't start again, so I pushed it home. When I got the car home I tested the spark off the coil and was getting none, so I went to Auto Zone and got a new TFI and Pickup for the distributer. Now the car starts and runs just like it did before...crappy.
When I got the car, it had a new distributer cap, a front mounted intercooler, 35lb "brown top" injectors, and a new cat and exhaust system with like a no-name turbo muffler.
When I push on my brakes, the go almost all the way to the floor, and a vacuum leak sound can be heard.
When I take the oil filler cap of the car, it begins to idle terribly, and if you hold your hand over the opening, you can really feel a strong suction, as the though the crankcase of the engine were creating a vacuum.
I've tried unplugging my knock sensor, to see if maybe my computer was retarded my timing for no reason under boost, but that didn't help.
I ran the engine diagnostic with an LED and on the KOEO test I got a code 23, which is "throttle position sensor out of range" I tried the test again, and got a code 11, so know I don't know what to think. I tried the KOER test and nothing happened, I tried about 5 times and followed the directions, and the LED would do the "fast blink" but then nothing else, and I waited a long time, still nothing.
I've got a new fuel filter, but haven't had a chance to install it yet. I still have no idea if its vacuum related, ignition related, or fuel delivery related. All my hoses are metal, and all of the fittings are nice and tight, and no cracks or anything. I sure do seem to have a lot more weird vacuum lines than my Chilton's book shows.
Anyway, yes I know this was long, but if you made it all the way through, do you think you might know what's going on with my engine? Thanks.
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84 TC
spearco svo fmic
4.10s
other goodies
2.3 X 15 psi > 4.6
First check for vacuum leaks. Go to Home Depot and get a male 3" PVC coupler and end cap. Put the 2 together. Drill a hole in the end cap and install a schaeder valve. Disconnect the VAM hose at the VAM. Tightly hoseclamp the whole contraption to the VAM hose. Now put an airhose on the valve and pressuize your system. You'll find any and all vacuum leaks immeditely!
Repair any vacuum leaks.
Then adjust your TPS. Article courtesy of NATO.
Idle / TPS Adjustment
by Keith Nubel
This article is intended to teach the basics of adjusting the idle and the Throttle Position Sensor on the 2.3 liter Turbo Coupe Thunderbird. It is recommended that your engine have a good tune up before you attempt to make any changes.
Tools Required
·Voltmeter with a DC voltage scale. ·Short Phillips screwdriver. ·Small adjustable wrench.
Components Involved
·Idle Air Control (IAC). ·Throttle Position Sensor (TPS). ·Throttle Body. ·Accelerator Linkage.
Adjustment Procedure
·First bring the engine up to normal operating temperature ·Turn the engine off and unplug the Idle Air Control connector from the IAC. This is located on the backside of the Throttle Body near the firewall. This device is a round cylinder approximately 5 inches long with a (2) bolt flange and 3 wire male / female plug connector. (see picture) · Start Engine. Using the small adjustable wrench on the idle adjustment screw, adjust the base idle to 700 – 800 RPM. (The idle adjustment screw is #1 in the picture below)
·Locate the Throttle Position Sensor (TPS) on the Throttle Body. This is also located on the backside of the Throttle Body near the firewall. This is a black plastic device with (2) screws that allow adjustment and (3) wire male / female connector. (see picture)
· Back probe the back of the TPS connector to connect the meter... The + (positive) side of the meter connects to the green wire. The – (negative) side connects to the black wire (SIGNAL RETURN). NOTE: you must connect the negative side of the meter to the black wire (SIGNAL RETURN). Do not just ground it to the chassis; it’s not the same thing. Back probing means sticking pins down the back side of the harness side of the connector for the appropriate wires. It can be tricky but is better than sticking pins through the wire insulation. The connector is left attached to the TPS. ·Using the small Phillips screwdriver to loosen the two hold down screws slightly, then rotate the TPS to change the voltage setting. Adjust the TPS output voltage to just under 1.0 volt. Most turbo tuners find that setting TPS voltage to around .90 - .95 volts works best. I set mine around .94 volts. When set, tighten the screws and recheck the reading. ·Turn off the engine. ·With the engine off, but key ON and the voltmeter still connected move the throttle linkage slowly from idle position to wide open and back to idle, looking for a steady increase and then decrease in voltage without any voids or dead spots. Any voids or dead spots would indicate a faulty TPS. ·Plug in the Idle Air Control. ·Start the engine. The engine’s idle speed should settle in around 1000 RPM. ·Take the Turbo Coupe for a drive and see how she runs.
This information is provided to you as a courtesy from the North American Turbo Coupe Organization (NATO). The user(s) of this information bare sole responsibility for its use and their own actions. The Author, NATO, or its members assume no liability.
Next remove the IAC, clean it out throughly with BrakeKleen and replace.
I have an 84 SVO with the same problem, but mine only does it when im like pushing it...so far but these things only get worse. Any who i did a complete tune up and re timing but still havent figured it out. Do we just need to get new Turbos???? lol that would solve the problem. lol
I don't make it to boost, just as soon as mine starts to spool it starts bucking and hopping. Things that have been replaced or checked----Dizzy rebuild(TFI and PIP replaced), coolant sensor replaced, tps replaced and voltage verified at .94vdc, air idle motor replaced, physical position of timing belt verified, timing verified at 10, plugs, wires, rotor, cap. My car will start and idle for about 1 to 2 seconds then die, it will do this until it gets warm then it will idle but it is not smooth. When i get it out on the road it just runs horrible, but in neutral i can rev it and it revs fine. I am researching the VAM now and will check it next. Does anyone have the pinout for it? You must eliminate what is not the cause to find the cause
Thanks Navysvo. I had already got my meter out and figured out the pin out for it. The pot was bad in it. I put a new VAM on it, pulled the plugs and cleaned and regapped them( my buddy had gapped them at .045, I left them at .030) and fired it up. Its running like a champ right now. Thanks for the help guys but don't worry, ill be back. I had an 84 SVO daily driver for four years and they require constant work. By the way Navysvo, I'm an old squid, GSM on the USS Hawes FFG-53 in the early 90's.
Hello, I too have a 88 Tbird Turbo but my miss is a little diffrent, Idles good and drives good until upper RPM and then stutters, seems to get a little better when warmed up - timing is good and just tuned with all Ford parts only thing is got a rebuilt distributor - can the octane rod have something to do with this? Since i doubt its the Turbo spec one
My junker had the same symptoms and the problem turned out to be that the wastegate actuator rod was broken off. Once I reattached it with a spring she worked fine...
I had same problem on my '84 back in the day when I did the DP head swap. Had to do swao in a hurry and it had some vacuum leaks here and wouldn't boost for $h!t. Tighten abd torque everything and do the Home Depot Trick. By the way I am also active duty Navy. I just hit my TWO-ZERO in January! 13.5 yrs NAVAIR and 6.5 as a recruiter. Just got back into the Turbo Fords again, by the way does a Turbo Probe (Mazda MX6) count?
1984 Mustang 2.3 Turbo Miss Under Boost 
