You are not currently logged in

Am I having injector failure?

Symptoms possibly caused by faulty fuel injectors:
 
• Rough or low idle (bumpy idle, feels like car vibration at idle)
• Engine Hesitation.
• Reduction in power.

Cure:
 

• Replace faulty injector(s).


I Diagnosis:
 

To diagnose injector failure; determine which cylinder is suspect. This can be done one of many ways. The easiest and safest way to determine which cylinder(s) may contain faulty injectors is to inhibit spark from each cylinder one by one noting the changes in RPM. This can be done by disconnecting the connector that provides voltage to the spark coil sitting on each cylinder while the car is idling. Do not disconnect the injector connector while car is idling, it may cause damage to the ECU. A cylinder is firing correctly if the RPMs drop slightly when power to the spark coil is removed. Hence, when plugging the connector back in the RPMs should raise slightly (and run smoother). This means that specific cylinder is getting the appropriate amount of fuel and has a good spark. However, if the RPM's stay the same after the plug is disconnected it means with or without spark that cylinder is not firing. A lack of fuel would be the next logical conclusion. Note the cylinder and continue with diagnosis for all the remaining cylinders. It is not uncommon for more than one fuel injector to go at a time.


II Measurement:
 

We now know which injector(s) are suspect. To scientifically prove the status of the injector it must be measured. An Ohm meter will be required to measure the resistance of the coil of the injector. With the engine off, the connector to the suspect injector(s) will need to be disconnected to gain access to the injectors terminals. A little trick to doing this (because removing the connector is by far the hardest part of the diagnosis). Grasp the connector by the plastic plug and carefully pull on it. There is a retaining clip that keeps them on (very good) but with enough "carefull force" the plug just pops off without the whole hassle of removing the clip. Overall be gentle with the wiring harness, they can become brittle and are expensive to replace. When access to the injectors terminals is had, measure the resistance (Ohms (Omega Symbol)) of the injector. If the meter is not auto-ranging, put it in the 10-20 Ohm range. The factory specification for a properly operating injector coil is between 10-14 Ohms. For instance: if the injector is 27 Ohms or 8500 Ohms or Infinity Ohms then it is defective and must be replaced.

Snives

Back to FAQ Index