That it's nearly impossible for all three ignition coils to go bad.This Switching signal is created by the ignition control module. That each of the individual coil packs sitting on top of ignition control module are controlled by a Switching signal.The five most important things that you need to know about this type of Direct Ignition System to be able to test the ignition coils, are: A lack of power since the engine is not firing on all cylinders.īasic Working Theory Of The GM 3.1L And 3.4L Ignition System.This smell is usually the surest indicator that the misfire will eventually damage the catalytic converter or of your car.This smell is caused by unburned gasoline from the misfiring cylinder overloading the catalytic converter's oxidation process.A 'rotten egg' smell coming from the tailpipe.Excessive tail-pipe emissions that, depending on how bad the misfire is, can be seen as black smoke coming out of the tail-pipe.Bad gas mileage that results from the engine not firing on all cylinders.Or other ignition system malfunction codes.The check engine light will be on on your instrument cluster due to:.The most common symptoms of a bad ignition coil are: To help you to diagnose this type of Direct Ignition System, the following sub-headings (below) will shed some light on the most common symptoms of a bad ignition coil, some basic working theory, the tools you'll need, and safety precautions you need to take when working on this type of Direct Ignition System (DIS). You'll find, on the column on the right, a box titled: Applies To and in it a list of most of the makes and models this testing info applies to. Also, Isuzu Rodeo and Trooper with the 3.2L V6 engine (92-95). Now in case you're wondering what vehicles this article applies to, it applies to most of the GM models (Buick, Chevy, Olds, and Pontiac) with either a 3.1L or a 3.4L. Coolant Leaking From Intake Gaskets (GM 3.1L, 3.4L) (at: ).Engine Compression Test GM 3.1L, 3.4L (at: ).Fuel Injector Resistance Test GM 3.1L, 3.4L (at: ).Troubleshooting Misfire Codes (GM 3.1L, 3.4L) (at: ).How To Do A Cylinder Balance Test (GM 3.1L, 3.4L) (at: ).Troubleshooting A Hard To Diagnose Misfire Case Study (GM 3.1L, 3.4L) (at: ).The following tutorials may also be of help: To see the complete list of 3.1L and 3.4L test articles, go to the GM 3.1L, 3.4L Index Of Articles. If your vehicle does not start and you need to test the ignition control module (ICM) or the crankshaft position sensor on this type of Direct Ignition System, see this tutorial here: Testing The Ignition Module And Crank Sensor (GM 3.1L, 3.4L). IMPORTANT: Before we go on, let me tell you that this article only tests for a bad ignition coil pack(s) and is geared more toward solving a misfire condition in which the car (or minivan or truck if you're driving an Isuzu) starts and runs but runs with a misfire. You can find this tutorial in Spanish here: Cómo Probar las Bobinas de Encendido (GM 3.1L, 3.4L) (at: ). TEST 5: Verifying The Ignition Coil's Switching Signal.

TEST 4: Verifying That The Ignition Coil Is Receiving 12 Volts.TEST 3: Testing Spark At Two Adjacent Towers Of Same Coil.TEST 2: Testing Spark At The Ignition Coil Tower.TEST 1: Testing Spark At The Spark Plug Wire.Where To Buy The Ignition Coils And ICM And Save.Safety Precautions And Guidelines When Testing The Coil Pack.What Tools Do I Need To Test The Ignition Coil Packs?.Basic Working Theory Of The GM 3.1L And 3.4L Ignition System.

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