Cascade Crew

[Raiden]

My Z is a turn key car. Turn the key and it starts right up! No thorttle needed. Well, today, I went to start my Z and i had to feather the throttle to get it going. Now, it' runs like crap? Like it's missing a cylinder or two? really odd. I replaced the wires, plugs, cap and rotor. It's on a 91 Z tpi engine. Stumped??? H E L P Please

[PonchoTA]

Clean out the EGR valve.
Check for vacuum leaks.

More than likely, while you were changing out the other things, a hose either broke or has come loose. A can of starting fluid is your friend!

hth
Paul

[Dewey316]

Is it having problems other than just at start up?

here is procedure for setting the IAC and TPS.

Idle Air Control
Tools needed:
Torx bit # T-20
Paper Clip
Small Punch
Take the paper clip and open it up and form it into a big "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' pins.

Turn on the ignition, but don't start the engine. Wait 30 seconds. Now, go remove the connector from the IAC.

Start engine. You are now going to adjust "minimum air". There is a Torx screw on the side of the throttle body. This is what needs to be turned to adjust minimum air, or more commonly known as "idle speed". It comes from the factory with a protective metal cap over it. If the cap is still there, use a small punch to knock it out. Set the idle speed to 450 rpm, rotating the Torx screw clockwise to raise rpm, and counter-clockwise to lower rpm. Once the idle rpm is set, turn off the engine.

Re-connect the connector onto the IAC. Start engine. Idle speed is now once again governed by the ECM, but your idle should be smooth and steady, approximately 600 rpm in Drive (for unmodified cars).

If you set an SES light by having the IAC disconnected, then after shutting down the engine disconnect the negative battery terminal. Wait 5 minutes. This will clear the ECM of all trouble codes. Re-connect the battery and drive the car for 20 minutes to allow the ECM to relearn your driving style.

Throttle Position Switch (TPS)
Tools needed:
Digital Volt-Ohm-Meter (VOM)
Jumper Wires (make your own)
Auto Xray Scanner (if available) will eliminate the need for VOM and jumper wires.
Turn on ignition, but don't start the engine.

With a scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.075Volts

With VOM and jumper wires: disconnect the connector from the TPS. Using your jumper wires, make a connection allowing some room for the VOM terminals to contact the jumper leads and read the TPS voltage.

If out of spec, loosen the two screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, that could mean a bad TPS switch and could be a cause of stumbling and driveability problems.

After setting the correct voltage, turn off ignition switch. Remove jumpers/scanner and reconnect the TPS connector as required.

[Twilightoptics]

Check TPS voltage if anything, IAC shouldn't have changed.

I think Paul is on the right track with a leak somewhere. Didn't happen to unplug that big fat vacuum line that goes from the corner of the plenum to the brake booster did you?

[Midnight Sun]

[Raiden]

I forgot to post the results of my not starting problem...........

Paid out the yang for a forged internal engine 3 years ago. consequently, I paid the guy under the table for a forged crank/rods shortblock. My starting problem turned out to be that the crank broke right behind the timming gear! The crank and rods were not forged! A mucho ty TY's go to Bhaas for helping me putting back the new engine which does contain eagle 4340 rods and crank:D So the reaons my car was not starting was that the crank was not spinning, hence, no spark.

[Schultzy89GTA]

ack!

That sucks man... glad you got it fixed.

-Schultzy