#1 cylinder misfire

I've had this issue off and on for the past year. My check engine light will turn on and stay on for a day or two then turn off. I do notice the difference when it turns on and when the check engine light turns off. My truck begins to shake terribly in idle and when I put it in gear and drive. It does get worse when I accelerate over 45 mph. There are days that it runs just fine but then it starts shaking without warning. It's just now starting to have a slight knocking noise. I've taken it to autozone to have them diagnose the issue and each time it's been the #1 cylinder misfiring. I've replaced all the spark plugs, spark plug wires and coil overs, both O2 sensors, fuel filter, new alternator (because it died) and a new battery. I do regular oil changes and maintenance to keep it running. It's a 99 Tacoma TRD and it does have 256K miles so it's showing it's age. I think it's time to have the engine rebuilt but what advice do you great people have for me? Any advice is appreciated.

 

Injectors?

 

Compression and/or leak-down test. Basic tests to be sure it's not an internal problem like a burnt valve.

 

It's probably that injector. These 5vz that are nearing the 300k mark are quite commonly having a problem with an injector or two going bad. Pull the spark plug out and do a compression test before replacing it, but I'll bet compression is fine. Get you a replacement, and the install isn't even that hard to do yourself.

Do NOT rebuild that engine yet! You are just beginning with your 5vz they will go a million miles.

 

This thread is very helpful.
My engine starting having the same issue of the #1 cylinder misfire error code (self diagnosed with a code reader) and the really rough idle developing intermittently in December. 2.7L, 4 cyl, 275K miles. I pulled all the spark plugs and the distributor cap and everything looks fine. Still using the stock 1996 wires, just replaced both O2 sensors this fall for another problem. Plugs, filters, etc were just replaced last year with a major check-up. Plus it gets regular maintenance and I just ran an injector cleaner in October. I'll try the injector replacement. I love learning a new skill.

 

First try swapping the #1 and #2 spark plug wires. (That is, put the original #1 wire from the #2 distributor post to the #2 spark plug, etc.) I had a bad wire even though the resistance check tested good. If the code changes to the #2 cylinder then you know that was the problem, and this test is a lot easier than moving injectors around.

 

This is good advice.

 

Sub'd for pics

 

Whoa, if you're still running the original spark plug wires at 275k miles, it wouldn't surprise me if the problem lies there. Didn't notice the mileage you had stated.

 

I was surprised as well when I saw they were the stock wires. And at the same time a little proud of my Taco for lasting so well. When I took it in to the local dealer for the major maintenance overhaul I expected more. Should have known better. I'll try the swapping the wires this weekend, and maybe replace them.

 

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