I nedd some help tuning a TPI set up I installed on my 81!!

TPS voltage?
Fuel pressure? (bosch ford injectors w/ adj fuel press. reg.)
Base timing?
Any thing else that needs to be set?

Ive had it running already but the idle floats up and down after a few minutes? Why does it have to be driven to run better as im told? ( still need aligainment) is this causing some problems?

The engine is basicly stock 30 over, edelbrock alum. heads, small cam for a TPI engine, daul exhaust, no emissions.

Any help would be great, as its ready to drive except for this!!

 

The methods to set base idle (to 450rpm) and to set the TPS voltages are on my site. The base idle setup will allow the ECM to use the IAC (under the TB) to control idle. If idle is still hunting or too high check for a vacuum (air) leak into the intake.

Initially set the fuel pressure (at idle with vacuum line disconnected and plugged) to around 48psi (if using stock size 22 lb/hr injectors). Later you can tune fuel pressure to max performance at WOT. With your setup, however, you may need more fuel pressure.

If you installed the full TPI setup there is an ALDL connector under the dash to the right of the steering wheel. You can jumper pins A&B (upper right) and use the Field Test mode (described on my site) to see if the ECM is going into closed loop mode at steady throttle settings.

The fuel trim is done by the ECM using Block Learn Mode (BLM) cell values as well as an Integrator. Data from the O2 sensor feedback gets stored into each BLM cell and is updated as you drive the car at various speeds and loads. So it takes a few miles or "normal" driving for the ECM to get enough data under various driving conditions to update each BLM cell for correct fuel trim at part throttle.

At WOT the ECM selects BLM cell #15, which always has the quiescent value of 128 (no fuel trim at WOT). This is why you can vary fuel pressure for best WOT performance and still have opimum performance at part throttle conditions. Ah, the ECM is a wonderful invention.

BTW, what year TPI setup & ECM did you install?

 

In addition, is the system you installed has an adjustable TPS, it should be set to .54 (+/- .075) using a digital volt meter. The TPS has three wires; use the top and second wire to connect the volt meter. Then, turn the ignition key to the "ON" position, but do not start the engine. Read the voltage; if you volt meter shows a (-) before the voltage it means you connected the meter backwards. This isn't a problem though; you can just swap the two connection wires or leave them as they are connected.

Then loosen the two screws which hold the TPS to the throttle body and rotate up upward to increase the voltage or downward to decrease it.

Once you get the setting you want, tighten the screws and make sure the voltage hasn't changed; it sometimes does as you tighten the screws. If it does change, just repeat the adjustment until you get it right.

Now, with the meter still connected, slowly open the butterflies on the throttle body while watching the voltage readings. The voltage should increase as the butterflies are opened. There should not be any voltage spikes (numbers suddenly jumping higher).

At WOT, the voltage should read higher than 4.0 volts.

Base timing is 6 degrees BTDC with the EST wire (tan wire with black stripe near brake booster) DISCONNECTED. Be sure to disconnect the battery for about 30 seconds or so after setting the timing because the ECM will store an error code when it detected the engine running with the EST disconnected.

You'll need a ScanTool or Diacom, etc., to check the IAC counts. They should be around 20 at closed loop idle.

You'll also need to make sure the system is going closed loop once the engine warmed up and idling for about 5 minutes.

Hope this helps,

Jake

 

1985 tpi and the ecm Im not sure but i think its from 92 camaro its the water tight one. They provided (street & performance) a vin # for a 2000 though? ITS also changed over to speed density

 

The '85-'89 Vette & F-body TPI used a Mass Air Flow sensor (MAF) to determine air flow directly; in '90 both cars went to Speed Density (SD) setup, which uses a Manifold Air Pressure sensor (MAP) along with other sensors to calculate air flow.

If your ECM setup is from a '92 it could even be for an LT1 engine (true for Vettes, not sure about F-body though). But for sure it is for the SD setup.

You need to truely ID the ECM setup so you can be sure you are providing all the necessary sensor info to it.