1998 Tacoma 2.7L Misfire (at idle?)

First of all, this is my first post in the Tacoma forum, and I am happy to be in good company.


My truck: 1998 Tacoma, 2.7L 4 cylinder, 235,000 miles.

The Problem: Recently the CEL came on and when I took it to the dealership, they said it was a misfire in Cylinder 1.

The engine idles somewhat low (500-750 RPMs) and sometimes the idle RPMs will jump between 500 and 750 RPMs. When it idles, it feel a little rough (cab shakes a little bit) but doesn't seem too serious. It drives perfectly fine, it's just the idle.

I didn't want to pay $300 for a diagnosis, so I decided to keep on driving it.

I changed the spark plugs and the wires.

The CEL went off for about a week and then came back on recently.



Any advice on a diagnosis is greatly appreciated! Thank you all in advance!


-Liam

 

Has the valve clearance ever been checked?

 

If you have distributor (I don't remember if 98 has distributor or coil pack) check the contacts. This is easy. Replace the spinning contact - cheap and easy.

Next could be dirty injector (lean). Spark plug could tell it. If one injector is dirty ECU woul compensate by putting more fuel in other cylinders.

Tle last (most expensive) is head gasket. Check leak down. Water leaking into cylinder can do that. Don't wait to long for diagnostic - you can ruin the head if it is injector or head gasket problem.

 

Welcome to TW!

https://www.yourmechanic.com/articl...-cylinder-1-misfire-detected-by-jamahl-walker

 

Thanks everyone! I checked the spark plugs, and it appears that in the first cylinder (where the misfire is), the plug is dirtier than the other plugs. So... dirty injector?

Thanks again!

Liam