96 3.4 Multiple misfire 1 and 6. Runs rough. When I pull the Number 6 spark plug wire while the motor is running it makes no difference in the rough idle whatsoever. I can hear the spark snapping. The Denso plugs are new and double ground. Gap is correct. Wires check out. All the coil packs primary checks out. Secondary won't register on 3 and 5. 1 is in spec. Camshaft sensor in spec. The injector on 1 is in spec. The 1,3,5, head was replaced. New timing belt and all marks exactly aligned.

 

time to check compression. Are you sure your cams are correctly phased with the crank?

 

Cams and crank on the mark for sure. No question. Will do the compression test.

 

Compression test is 190 or higher on each cylinder. Spec says 145 min. Leak down test on cylinder 1 and 6 showed no loss of compression after 20 minutes. Coil packs replaced. Spark plug wires replaced. Ran a real time scan with the engine running and the timing is in spec. O2 sensors good to go. TPS can't be adjusted. Spark plugs are new. Cylinder one and six plugs do show small amount of fouling. Which is consistent IMO of the fuel not being burnt completely. Again I can take number six boot off while running and it makes difference in the idle of the engine.

 

Crankshaft senor ohms out in range warm and generates consistent voltage when the engine cranks. Camshaft senor ohms out warm and cold. I am thinking mechanical issues. Perhaps a cam lob on six. Or injector. I am puzzled by the miss on 1. New coil packs and spark plugs. New head on the passenger side. I didn't do the work on the head though. All marks spot on.


The motor won't start after I pulled the crankshaft sensor. Cleaned it, tested it and put it back in. Tested the sensor for voltage when I put it back on. Any advice would be helpful.


All sensors check out. All ignition parts replaced. Makes me think mechanical. ECM possible but very unlikely. Voltage is in spec.

 

I'd move a different injector into the #6 position and see if it changes anything. Also you didn't say what codes it was throwing.

 

0300
0301
0306


That's it.

 

Definitely pull the covers and check to see if your cams are wiped. Motor oil these days is pretty good destroyer of camshafts.

 

are the intake cam and exhaust cam phased to each other properly? valve clearance withing spec?

 

Excellent questions. On the cams and the valve clearance.