2000 chevy tahoe has p0301. spark plug on #1 and wires are ok.rotor and cap is new. erase the code and run the eng. around the block and p0301 is back. what cause the p0301 keep coming back.

Code P0301 indicates a misfire in cylinder 1 of your 1996 Toyota Corolla 1.6L1. The most common causes of this issue are faulty spark plugs, worn-out spark plug coil packs, or faulty ignition system 123. You mentioned that you have already replaced the spark plugs, spark plug wires, distributor cap, and rotor button. However, it is possible that the new parts you installed are faulty or not installed correctly. You may want to double-check that the spark plugs are gapped correctly and that the spark plug wires are connected to the correct spark plugs

Code P0401 indicates a problem with the exhaust gas recirculation (EGR) system . The EGR system is responsible for reducing the amount of nitrogen oxide (NOx) emissions from the engine. The most common causes of this issue are a faulty EGR valve, clogged EGR passages, or a malfunctioning EGR vacuum modulator . Since you have already replaced the PCV valve, it is possible that the new part is faulty or not installed correctly. You may want to double-check that the PCV valve is installed correctly and that the EGR valve is functioning properly. If these two code problems persist, it is best to take your car to a trustworthy repair shop to diagnose the issue as quickly and accurately as possible .

P0301 Code - Cylinder #1 Misfire
A P0301 code means that the the car's computer has detected that one of the engine's cylinders is not firing properly. In this case it's cylinder #1.

Symptoms may include:
- the engine may be harder to start
- the engine may stumble / stumble, and/or hesitate, other symptoms may also be present.

A code P0301 may mean that one or more of the following has happened:
- Faulty spark plug or wire
- Faulty coil (pack)
- Faulty oxygen sensor(s)
- Faulty fuel injector
- Burned exhaust valve
- Faulty catalytic converter(s)
- Running out of fuel
- Poor compression
- Defective computer

* This conditions is the same when code is P0302 or P0303.

Possible Solutions:
If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.

If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.

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A random misfire code is usually a p0300 and this is usually caused by a clogged/restricted catalytic converter or exhaust system. Lets say this is a v8 if a certain cylinder wasn't firing it would be a p0301 or p0307 for example in which I'd suggest for you to inspect your spark plugs to see if they are fouled and then to test the circuit for a good spark by placing your plug wire with plug installed against the manifold and have someone crank the motor. A high voltage spark will be white or slightly light blue a weak spark wolud be an orange/reddish color which would denote a faulty plug wire/coil pack/ignition coil etc etc. A mechanic or shop with a dwell meter can cancel out each cylinder to determine if that's at fault but my money's on the cat.

I would replace
1. spark plugs. Do not go cheap on the plugs use the proper AC Delco spark plug
2. cap and rotor
3. spark plug wires
4.fuel filter
and then i would have a fuel injection cleaning done . there is not a timing adjustment or air fuel adjustment this is all done by the PCM ( Powertrain Control Module )

DID YOU REPLACE DIST CAP AN DIST ROTOR,NOW CHECK TIMING BELT TO SEE IF IT JUMPED

Do an injector balance test and a cylinder leakage test. Lets make sure its not fuel related. Most important lets make sure you don't have a vacuum leak.

P0301 is a DTC code that indicates a misfire to cylinder one. It could be a bad spark plug, spark plug wire, rotor and cap, a dirty fuel injector, or the worst a bad head gasket. Cylinder 1 is the first cylinder on the drivers side, towards the front. Start with the simple and check the spark plug wire and add fuel injector cleaner to the gas tank. Good luck and hope this helps you get you van running 100% soon. If that did not help, then your going to have to do a tune up by replacing the spark plugs, wires and rotor and cap. You can get all the parts you need at Auto Zone and they can give you the step by step to get the job done with common tools in under 2 hours of your time. Keep me posted, be glad to know you got your van running 100% again soon.

Did you swap out your distributor cap and rotor? Try that first - it's not going to be the cat. You may be losing compression in cylinder #1 one... Hope its the cap/rotor...

Check the spark wire for the #1 plug. I had one get burned by the header, I would check it for burns or cuts. Sorry I couldnt help more.

have you checked the tps sensor?