2007 Lexus RX350 misfire ignition fuel

SUV problem:

I have a slight misfire on this SUV and I need your help. I confirmed this ignition problem after getting codes from both misfire on cylinder #1 and the igniter circuit fault. Do you think I can test and do repairs with the tools you recommended in ATS? The fuel pump was just replaced 3 months ago and the dealer told us yesterday that it was within specs execpt they are asking too much to do this misfire/ignition problem. Thanks in advance.

ATS Adviser:

The fuel injectors and igniter circuits can be accessed once you got the "remove and install" info that you will get from ATS. It is pretty much straight forward but sometimes, you need to buy those metric tools to remove those bolts and fasteners. I usually take a picture of what I am doing before taking the parts out and saving them in my laptop.

Testing injectors can be done by common techniques like using a noid light tester to compare the brightness of the noid lights of 2 adjacent injectors. Is it steady or fading as you crank? The injectors can be ohmed out for comparison and comparing resistance of each injector as per specs in the manual. The injectors has to be swapped and see if the fault code moves.

Using a voltmeter, you can get the voltage of the power supply for the injectors (brown wires) at KOEO in the injector terminal harness or at the IG2 relay located in the left side of the engine compartment. You can test for shorts by removing the IG2 fuse and check if there is 12 v between the relay and injectors. Each injector coil will be supplied ground by the ecm at pins 2,3,4,5,6,7 terminals during cranking.

To check the igniter wirings:

You need to check the 4 wires going to each igniter primarily the power supply (red wires) and ground wire(white black wires). Do it with a voltmeter at KOEO. The IGf and IGt signal wires can be checked for continuity between the coil and ecm terminals as shown in the diagrams. But do it only if the spark tester is not showing blue spark during cranking.

Remember to verify the real cause of misfire by checking the mechanical condition of the engine like the engine compression and vacuum readings. If OK, do the easy parts first like crank and cam sensors which both affect the operation of the injector and igniter circuits. The PCM can be tested by testing the vref signal at TPS sensor at pin 5 (VC signal) is present at KOEO.

Check this approximate 2007 Lexus RX350 Ignition Wirings below. Note that the power (red), ground (blue) and GTF (brown) signals are common connections while the ECM sends individual ground signal to the igniters IGTs (top) and injectors (bottom).



2007 Lexus RX350 Ignition Wirings

You can get the EXACT wiring diagram from most parts stores if you ask for it while buying parts or get it FREE online 24/7 when you join ATS.

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