Sendero
01-22-2006, 10:13 PM
If you have a no start situation on a 1996-98 or 99-02 4V Cobra engine even though you have verified fuel and spark delivery, you may the same issue that I just experienced.
Symptoms:
The car turns over fine but acts like it has a weak spark. In other words it almost fires but doesn't. (ie It turns turns turns fires on two cylinders then turns turns turns)
Diagnosis:
After verifying fuel and spark begin your diagnosis by pulling the intake tract. Make sure you detach the MAF and Intake Air Sensor connectors. Unplug the Idle Air Control valve tube from the intake tract, but leave it attached on the engine side. Now, take your finger and plug the Idle Air Control valve tube making an airtight seal. Have a buddy get in the car, crack the throttle slightly and crank the car. If the car cranks, then you have found your problem, if not then you have another issue in need of further troubleshooting.
Note: The car will not idle with the IAC tube blocked and the throttle blades completely closed, this is normal and by design.
Resolution:
Congratulations, you have diagnosed a failed/stuck Idle Air Control valve. Verify that your electrical connections are corrosion free and firmly snapped in place. After that, take a rubber mallet and give the IAC a couple of good whacks to unstick the mechanism. Test the fix by trying to crank the car using the diagnosis method outlined above. After the car has started, remove your finger and allow the throttle to completely close. The car should idle on its own, if not repeat fix whacks one more time. If the second application of whacks does not fix the issue, replace the IAC with a known good unit and retest.
Symptoms:
The car turns over fine but acts like it has a weak spark. In other words it almost fires but doesn't. (ie It turns turns turns fires on two cylinders then turns turns turns)
Diagnosis:
After verifying fuel and spark begin your diagnosis by pulling the intake tract. Make sure you detach the MAF and Intake Air Sensor connectors. Unplug the Idle Air Control valve tube from the intake tract, but leave it attached on the engine side. Now, take your finger and plug the Idle Air Control valve tube making an airtight seal. Have a buddy get in the car, crack the throttle slightly and crank the car. If the car cranks, then you have found your problem, if not then you have another issue in need of further troubleshooting.
Note: The car will not idle with the IAC tube blocked and the throttle blades completely closed, this is normal and by design.
Resolution:
Congratulations, you have diagnosed a failed/stuck Idle Air Control valve. Verify that your electrical connections are corrosion free and firmly snapped in place. After that, take a rubber mallet and give the IAC a couple of good whacks to unstick the mechanism. Test the fix by trying to crank the car using the diagnosis method outlined above. After the car has started, remove your finger and allow the throttle to completely close. The car should idle on its own, if not repeat fix whacks one more time. If the second application of whacks does not fix the issue, replace the IAC with a known good unit and retest.