Hello. What is the year, make, model? Is it 4X4?
What was the original reason all these parts were replaced in the first Place?
Thanks.
Did you check spark on all the wires?
Is the security/theft light on the dash solid or flashing?
Wow!
The spar issue is concerning. I would check spark on all other cylinders and see which ones are firing.
If you have spark on one cylinder but not another, I would be suspicious of a distributor cap or distributor problems.
The caps are notorious for going bad or the rotors would burn through. But, you changed that. I have seen bad new parts so don't eliminate that yet.
First... Check for good spark. You are looking for 30KV. Meaning, spark should jump at least 3/4 of an inch and be blue in color. Not red or white. You can use a screwdriver with a wirre attached to the negative battery post. This will keep you from getting shocked. If weak spark from the coil, replace the coil.
If spark is good, recheck the cap and rotor. Replace as needed. If you have spark out of the cap on every cylinder but no spark on the end of the wire, well, bad wire(s).
Now, for the distributor... The metal ring on the top of the distributor can come loose and spin causing spark to not be properly distributed at the right times. You will end up with no spark out of the cap or spark out of the cap on certain cylinders. Position the #1 cylinder to TDC. Then, check that the rotor is pointing to the #1 cylinder on the cap. If not, check your distributor for slipped top rotor mounting cap, Broken shaft, broken gears, or even a broken cam. Also, excessive play in the distributor will cause a nostart.
Let me know what you find.
Assuming you are testing for spark at the cap...
If not, recheck your firing order as shown in the diagram.
If ok...
I know this will be a little hard to believe, but you have a defective distributor cap. You have spark going into the cap but no spark going out.
Purchase a quality cap and rotor. I suggest AC Delco or Echlin. Install. Recheck your spark.
Defective distributor caps have plagued the auto repair industry for years when it comes to this applictaion.
Let me know how you come out.
Now, let me ask you this. Spark at the coil...
Is spark coming out of the coil rythmic? Meaning, does it fire for each cylinder or does it seem like it skips cylinders? Basically, does spark come out of the coil for each cylinder?
Did you say white spark?
Good strong spark needs to be a blue color AT LEAST 3/4 inch long.
If you have white spark, you have weak spark.
What color is your spark line when 3/4 inch long?
Wow, tough without seeing it. You can use your screwdriver with the wire attached to ground to see how far spark will arch from the coil tower.
At 3/4 of an inch it should be a bright blue color. as it gets longer, up to 1 1/2 inch it will get white/pink.
Best thing I can tell you is to check with a known good vehicle so you know what it looks like.
You might have a wak coil. The resistance in the cap/rotor filters out 1,5,6,8 dues to higher resistance.
You can always throw a coil at it and see what happens.
Ok.
Lets hold on here a minute.
Start from scratch.
Back to my first answer.
Spark out of the coil. Good spark? Blue at least 3/4 inch. It will jump up to 1 1/2 inch but lose the blue color.
IF you have good spark into the cap, you should have good spark out of tha cap. If not, bad cap or rotor. Or bad distributor.
So... Lets check for proper spark first.
I have no doubt that you are losing patience with this. Time to clear your head and look at what you got.
So, review... You have good fuel pressure. Do you have good spark?
All an engine needs to run is fuel, air, and spark. In correct amounts and timing.
OK.
I had a good discussion about this vehicle at work with my coworkers. All ASE certified.
Came to the conlusion that there needs to be something wrond with the distributor.
We agree that you should set the engine to #1 DTC. Remove the distributor and inspect it for broken teeth and make sure the set pin is not loose.
The Camshaft Position (CMP) sensor is located within the distributor. The operation of the CMP sensor is very similar to the Crankshaft Position (CKP) sensor. The CMP sensor will provide one pulse per camshaft revolution (1x signal). This signal will not affect the driveability of the vehicle. The VCM utilizes this signal in conjunction with the crankshaft position in order to determine which cylinder(s) are misfiring
So, the cam sensor is not it.
Did you double check the rotor bor burn marks?
Is the spark into the cap looking as strong as out of the cap?
Back to the strength of the spark. Is it blue in color at 3/4 inch and is it pink/white at 1 1/2 inch?
Hello. I have been reading your post and I have one question, have you observed the rotor turning with the cap off?
Ok, I have a few suggestions. First check the wiring and connections to the crank sensor. The terminals can become weak. Also check the wiring around the engine paying close attention to the area on the passengers front of the engine where the wiring runs down to the crank sensor. I have heard of many cases where the wiring is chaffed and grounding out on the Alternator bracket and the exhaust manifold.
Also check the wiring around the back of the engine at the top, same as the front.
Is there a crack around one of the screws that holds the cap down?
How many caps and rotors have you tried? Have you tried with the cam sensor unplugged?
Ok, I had another expert post the following as well and It really makes me wonder.
BB"I'm not sure if this will help, I'm sure you have already seen it. The firing order in collection to the miss. look at the lay out on the cap. It's hitting on 4 and 3, 7 and 2. Missing on 1 and 8, 6 and 5. All of this is right across from each other. Could it be he could have gotten all those caps and be defective? "
THe dealer will be better quality but to get 2 defective really is rare.
I am also thinking that the cam sensor may be at fault. Normally it is there for misfire diagnosis, but there is a chance that a faulty sensor can do odd things. If we are sure about the cap and rotor, then try the sensor.
Chevy Technician
GM Grand Master Technician 2007. 9 years Automotive experience, 7 years with GM. Just Answer Mentor