I have a 2002 4.0L V6 Laredo. I wonder how I can make sure that all of the cylinders are firing at ignition and during the truck is running.
thx

 

Could alway run an extra wire and touch your tongue?? Or not. How about a timing lite with an inductive sensor, swap it from wire to wire, it will only flash on the plugs firing. How about an in line light, getem at the auto supply store, looks like a high tension wire plug with light in plastic case, trouble is you need 6, or swap from line to line, watch for that shock, the amps are low but the volts are high. How about pulling the plugs to see if colour is good, light tan is good, black junk is bad, light black is only ok, or get your buddy to do the 1st suggestion with the extra wire and the tongue thing? What are you trying to learn about your engine with the firing info, do yu have suspicions of troubles??

 

it takes 2 3 sec of ignition before the engine fully fires and also shakes a bit at first ignition. I used to have a mercedes benz 500SEL 8-CYL with similar issues. it turned out that 2/8 of the spark plugs were out of order. other than that all is fine with the truck. I do not know if I should take it for mechanical inspection cuz I just bought it and everything was supposed to be ok as a certified vehicle.

 

An 02 has coil on plug so you cant use a timing light. Usually if you have a miss bad enough it will set a dtc. Is the check engine light on?

 

all lights are ok. I always wait until all the check lights go off before ignition and I do not press gas pedal at ignition.

 

You mean in-line 6 cyl right?

 

yeah right straight 6 with 4x4.

 

If you had a plastic pair of pliers you can pull a plug wire off one at a time, you can do it with your hands but its tricky to not get shocked. Sometimes it helps to unplug the wires just enough that you can lift them off before you start the engine.

If your mainly concerned about if all cylinder are contributing you can unplug the injectors one at a time and see how it changes.

 

pull thr plugs and look at them