Boost controler

Part of my continuing problem of the car falling flat on its face above 3000 rpms was the TFI connector retaining clip was broken. I replaced the old one with one donated from the JY and the car will now pull to 5000 rpms in 1st through 3rd gears (175,000 miles I don’t want to spin it too much faster until I get the spare engine together) however in 4th & 5th gear it still falls flat above 3000 rpms if the boost is over 8-10 psi.

Could the boost limiting device under the fan controller be my problem? Since I bought the car it would pull 15 psi of boost in all gears up to the 3000 rpm limit, but from several post it looks like it should be limited to 10 psi in 4th and 5th. I am guessing the computer senses over boost in high gear and is shutting fuel off.

We have a pretty good electronics division at work is the boost controller something we could reverse engineer?

http://www.boostvalve.com/

Try this link, its easy, cheap, and makes a world of difference in driveability. When you say "falls flat on its face", do you mean it loses power? Done a tune up lately? Motorcraft parts? Could also be fuel pumps going bad. Can you hear the fuel pump over the engine?

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88 5-spd. bypassed BCS, cleared cat, Gillis valve,ranger roller, no major mods yet.

Thndrchckn420,
It loses power...however in the first 3 gears it spins right up and if I feather the gas pedal to keep the boost below 10 psi it will accelerate smoothly, but as soon as the boost goes over 10 it loses power. When I first got the car it would lose power in all gears over 3000 rpms even after doing the tune-up stuff (plugs, cap, rotor, wires, FPR, fuel and air filter. After changing the TFI plug the car will now spin (with power) up to 5000 with my foot on the floor except in 4th and 5th.
I checked the fuel pressure at idle and get 45-60 psi (line connected and disconnected). Having trouble justifying $40 gauge for over 70 mph freeway speeds to test pressure under full boost when the money could be used towards the purchase of a new pump.
I guess the question should have been...Can I by-pass the boost controler for testing purposes?

If it is loosing power as the boost goes up, I think it might be that the knock sensor is sending a signal for the computer to pull back timing. If the BCS is bypassed, (that is, the vacuum lines are routed so that it has the same effect as a continuously energized/open BCS,) you will always get about 15psi boost. If the electrical plug on the BCS is disconnected, you should always get around 10psi boost.

The BCS would be real easy to reverse engineer - Signal present, air valve open. No signal, air valve closed.

Hope this helps

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Mike Walsted - NATO member
1986 5-speed TurboCoupe and 1985 5-speed XR7

With the stock boost controller in the circuit, you are only going to get > than 10 psi above 4000 rpms in the upper three gears.
This assumes you have a later build 88 that was meant to deliever 15 in all gears.

With 175 K on the car, the problem could be a few things. If yo uhave the original fuel pump or a stock replacement, it may be getting weak. Run the Fuel System Diagnostics in the Technical Articles first and let us know.

WOW, that sounds like my car, except it makes 15 pounds in all gears even with the fule switch to regular. it has alot of gitty up till about 3 grand then has nothing. i do know it has an intake leak. i took off the filter and plugged the intake with my hand and it ran fine, hardly stutterd. but the car had a real cheap exhaust job on it, after the cat it goes into a single 2inch tail pipe. try hitting your car with a timing light, see if u have an intake leak.