I get no spark to number 1 spark plug. I have checked or replaced spark plugs, spark plug wires, distributor cap, ignition rotor, igniter, and ignition coil. But still have no spark to the spark plug. The engine starts and runs rough idle and uses a lot of gas. help
Well, you seem to have already replaced just about all primary and secondary ignition system components. If the engine will start and run, just badly you ARE getting spark, or some spark anyway.
So, I would do a compression test on all cylinders and see if that cylinder is much lower on compression. If it is you probably have a valve problem in the cylinder head.
Removing the cylinder head and doing a valve job is probably what is needed. Remove the valve cover and inspect for damage first though and make sure push rods and valve springs are in good shape and lifters are working on all cylinders.
We call this a “dead hole” when the internal engine parts are not moving or they are just flat out worn out and compression inside the cylinder can not take place.
Not sure what kind of vehicle this is, but if you have a metal timing chain it could be possible that the chain has “jumped time” meaning it has excess slack in the metal chain and has physically jumped a tooth on the timing gear sprocket. Rare, but I have seen it happen. This will change the ignition spark firing order and could cause your issue.
You would need to manually check the slack in the timing chain and find “Top Dead Center” on the firing order.
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