I have a straight 6 [engine](/topics-engine-toyota/) and ...

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Okay great walk me through

There are a few things to consider here with your issue: . 1. There is a difference between getting fuel and getting the appropriate amount of fuel. A sticking or clogged injector will still spray fuel but it won't provide enough for proper combustion. 2. A weak spark is different from a good spark, even though they are both sparks. Make sure the spark is a crisp blue spark. You can have a weak spark and still have combustion issues. . Back when these vehicle were produced, diagnostic strategy was very incomplete compared to today. Most of the diagnostics involve swapping components between cylinders to see if the misfire moves cylinders. The other strategy is to swap with a good known part to see if the issue is resolved. Most electronics diagnostics on these early 90's Toyotas and Hondas all were parts swap strategies. . **However, if you have not tested compression in that cylinder this would be the first place to go. Assuming you have good spark and fuel, compression and air are the only two other components of an internal combustion engine. I would test the compression. Standard should be around 149 psi with a minimum of 114 psi. Then check the cylinders on either side of cylinder #4 for their compression. A variation over 7 psi indicates internal engine trouble.** . I’m glad that I was able to answer your question today. My goal is to ensure you receive a 5 STAR experience. Once you’re satisfied with my answer please take the time to rate me 5 stars at the top of your computer screen or by following the link on your phone. These ratings are extremely important to us experts. Tips are never expected by greatly appreciated as they make up a large part of our income. If you have further questions, please request me by using the following link and entering your question into the box. This ensures your questions comes directly to me: [https://www.justanswer.com/car/expert-yourautoinspector/](//www.justanswer.com/car/expert-yourautoinspector/) Thanks again for using Just Answer!!

What could be causing one cylinder to be misfiring even tho it's getting fuels oxygen and sparks

Compression.

Worn piston rings, damaged cylinder walls, valve/head issues all can cause a loss of compression. Loss of compression creates a lack of combustion. Testing the compression as I've outlined above is the next step.

Well I have interchange wires plugs and injectors and it's the same problem cylinder 4 not firing ... u don't have a tool to check the compression on the cylinder what else can I do what do you suggest what else could be causing the issue?

That should be the only thing if you've confirmed that the spark and fuel is good. Only other possibility is a mechanical issue with the valves or excessive carbon deposits in that specific cylinder. But remember, swapping the spark plug and wire only confirms that portion of the ignition circuit, it could be in the distributor, cap or rotor itself if you don't have a good contact on that post. Pull the cap and check for carbon on the post for cylinder #4.

there wasn't any deposits at number 4 in the distributor cap so I'm guessing as you've said it's inside the engine the problem lies

Yes, most likely. Next step is the compression test to confirm.