What should the TPS be on my IAC?

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.

How does the ECM know which injector to activate?

Using the cam sensor readings, as well as the crank sensor readings, the ECM knows exactly which injector needs to be activated. The synchronization of the cam and crank shafts in an engine is the key to engine performance. This synchronization is also referred to as the engine timing.

What are the DTC codes for the throttle position sensor?

TPS diagnostic trouble codes (DTC’s) stored in the vehicle’s computer’s memory. P0121: Throttle Position Sensor Performance. P0122: Throttle Position Sensor Circuit Low Voltage. P0123: Throttle Position Sensor Circuit High Voltage. Really bad gas mileage. Transmission does not shift out of second gear.

How to change minimum air setting on 1994 ECM?

If you don’t have a scan tool and you are working with a pre 1994 model year ECM, you should be able to adjust the minimum air setting by doing the following steps… 1) With the IAC valve connected, ground the diagnostic (ALDL) terminal (same as you would do to flash trouble codes thru the check engine light).

Is the distributor engine equipped with a CMP sensor?

The Distributor engine does not use a separate CMP sensor. It utilizes a conventional distributor, equipped with a Hall effect device, for this function. The following symptoms can be caused by intermittent wiring connections or faulty signal to the EMS. Camshaft Position Sensor Symptoms

How does the camshaft position sensor work on a distributor engine?

This is activated by a single vane, and is driven by the camshaft. On Three Wire Sensor engines, the Camshaft Position (CMP) sensor is a variable reluctance sensor, which is triggered by the high-point mark on one of the camshaft sprockets. The Distributor engine does not use a separate CMP sensor.

How do you install a CMP sensor on a car?

When installing the sensor, the connection must be in the exact same position. Position the No. 1 cylinder at 10°ATDC, then matchmark the CMP sensor terminal connector position with the engine assembly. Remove the camshaft position sensor retaining screws and sensor. Remove the retaining bolt and hold-down clamp.

How do you adjust idle speed on IAC?

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”.

Is the idle speed governed by the ECM?

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.

How to reset throttle body calibration [ step by step guide ]?

Make sure that the accelerator pedal is fully released. Turn ignition switch “ON” and wait at least 2 seconds. Turn ignition switch “OFF” wait at least 10 seconds. Turn ignition switch “ON” and wait at least 2 seconds. Turn ignition switch “OFF” wait at least 10 seconds.

How does a GM throttle body relearn procedure?

A motor and gear reduction set inside the throttle body opens and closes the throttle plate to accomplish your request. Over time, carbon buildup can accumulate around the throttle plate, changing it’s “home” position. If the buildup occurs gradually, the PCM “learns” the new home position.

What should idle speed be on IAC 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.

Can a bad IAC cause a DTC to set?

If you do not hear a change in RPMs, do not assume the IAC is bad until you do further testing. Also, this test may cause DTCs to set. With the engine off, unplug the IAC. Then start the engine and listen for an idle speed that’s either too high, too low, or fluctuating.

Can a bad IAC cause an engine to stall?

A faulty IAC can starve the engine of air at idle, resulting in stalling. Engine Won’t Start Although rare, there are instances where a faulty IAC can throw off the air/fuel mixture enough to prevent the engine from starting.

When to clean throttle body 4.3L V6 position sensor?

Clean the throttle body to fix a sticky throttle on a 4.3 in a Blazer, S10, Silverado, and express. Also GMC Jimmy, Sonoma, Sierra, Savana. This applies to 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007.

Can a bad throttle position sensor cause idle surging?

Idle surging can be caused due to other issues in the car, but if it happens in conjunction with other throttle position sensor symptoms, the culprit is often the TPS. At idle, the ECM will not get the correct information and the throttle will variate randomly causing idle surges. 3) Check Engine Light

Where is the Torx screw on the throttle?

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.

Why does the idle go up after cleaning the throttle body?

The idle is going to be high at first until the computer relearns the idle again. Cleaning the throttle body allowed more air to enter the engine, and the computer is compensating by adding more fuel.

Can a dirty IAC cause a rough idle?

A dirty IAC can cause a rough idle. A dirty throttle body can harm performance and cause rough engine operation. When the throttle body or iac is removed a new gasket must be used to properly seal the connection to the intake.

Do you have to warm up the engine before disconnecting the IAC?

Start the car and let it warm to operating temperature. The down side to this is the heat emitted from the engine as you try to disconnect the IAC in the following instructions. But, the engine has to be warmed up. Sorry. Use a jumper wire to ground the “Test” terminal on the ALDL connector.

Why does the throttle plate keep opening and closing?

This can happen if the throttle plate is opened and closed over and over again at a rapid pace. A computer scan tool would then need to be used to monitor the inputs of the throttle motor and the throttle position sensor to see what is going on.