Starting issue

Tiny
DADDYOGRAY
  • MEMBER
  • 2004 SUZUKI FORENZA
  • 2.0L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
My car will not start unless I pump the accelerator, then backfires bad then starts. But revs as high as it can go and does not stop. So I have to shut it off right away. What is going on with it?
Tuesday, May 8th, 2018 AT 2:35 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,170 POSTS
Hi and thanks for using 2CarPros. Com. Your vehicle has an idle air control valve, IAC. The component allows metered air to enter the engine so it can run without touching the throttle. The first thing I would recommend is to scan the computer to determine if there are trouble codes stored which may indicate where the problem is coming from. If you find nothing, I have attached a flow chart to guide you. Additionally, here are the directions specific to your vehicle from AllData. Please pay close attention to the relearn section. If for any reason the power supply was interrupted, you must go through the relearn process.

Diagnostic Aids:
If the idle is too high, stop the engine. Fully extend the Idle Air Control (IAC) valve with a IAC driver. Start the engine. If the idle speed is above 800 rpm, locate and repair the vacuum leak. Also, check for a binding throttle plate or throttle linkage or an incorrect base idle setting.

Test Description:
The number(s) below refer to step(s) on the diagnostic table.
The IAC valve is extended and retracted by the IAC driver. IAC valve movement is verified by an engine speed change. If no change in engine speed occurs, the valve can be removed from the throttle body and tested. Connect the IAC driver to the removed IAC valve and turn the ignition ON. Do not start the engine.
This step checks the quality of the IAC valve movement in Step
Fully extending the IAC valve may cause an engine stall. This may be normal.
Steps 2 and 5 verify proper IAC valve operation. This step checks the IAC circuit for a wiring or ECM fault.

Idle Air Control Valve Reset Procedure:
Whenever the battery cable or the Engine Control Module (ECM) connector or the ECM fuse EF22 is disconnected or replaced, the following idle learn procedure must be performed:
Turn the ignition ON for 5 seconds.
Turn the ignition OFF for 10 seconds.
Start the engine in park/neutral.
Allow the engine to run until the engine coolant is above 185 °F (85 °C).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
If the vehicle is equipped with an automatic transaxle, apply the parking brake. While pressing the brake pedal, place the transaxle in D (drive).
Turn the A/C ON for 10 seconds, if equipped.
Turn the A/C OFF for 10 seconds, if equipped.
Turn the ignition OFF.

The idle air control valve is located on the throttle body. This component is at the end of the air induction tube that runs from the air filter box to the engine. I have attached a picture for your review. Additionally, I attached a picture of where the IAC is located on the throttle body.

I hope this helps.
Take care,
Joe
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Tuesday, May 8th, 2018 AT 7:25 PM

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