mybuick started a little slow but it was cold out last night so I figured it will warm up. I got out of town and halfway up the hill and it started miss firing badly so I turned around and coasted home and was told I was on fire 🔥 for d out it was the catalytic converter was red hot got back to where I started from and let it cool off. I called around and was told it was something was dumping fuel in the system. Probably a bad plug or coil. I got the coil pack off, what a pain in the arm. I changed the rear plugs, they looked great just wore out. One of the coils had some discoloration around the no. 5 and no. 3 towers. How do I test the ohms on the coils what are they suppose to be. The bottom of one looks like it got warm the bottom looks like it got 🔥 it is the no.36 coil and the 2,5 coil is getting close to dying. It only has 220,000 miles on it.

 

First we need to know , year , model and engine size.
From what you describe , regular maintainence has been neglected.
There are some things we need to do and that is to make sure the routine maintainence items are replaced. You might get away with it for a while, but you will need to tend to them.
Depending on age , year etc. you might be better off just replacing all the plugs and coils.
The next concern is how much damage was done to the converter. If they get hot enough , they melt internally and will become restricted . Replacement is not cheap.
An over fuel condition might also be involved. All these things have to be checked out in order to know where we stand.

 

it is a 02 rendezvous with a 3400 engine i am pretty sure one of the coils are bad. If one is bad the others are not far behind. I need to know what the resistance is suppose to be in the windings.

 

Do you mean 3300 engine? One of the best engines GM made.

 

Measuring coil resistance is only reliable if the misfire is total. Coils can and do breakdown under load. If you are sure which cyl is misfiring. switch coils and if the cyl changes , you have your answer. Also , a bad plug wire will allow for a misfire. They need to be replaced on a routine basis ..
A defective fuel injector can also dump fuel into a cyl. You need to eliminate each possibility with different tests or if you don't have the equip , just replace the plugs, coils and wires. Now you have a reliable ign syst. If you still have the misfire problem , I would switch injectors and if the miss moves you have your answer.

 

it says 3400 on the top of the engine. I changed the coils and module and got it started. It idles ok but as soon as I give it gas it starts backfiring. I haven't changed the plug wires yet that is next it just takes money.

 

I have something you might check. and that is the resistance of the fuel injectors. It sounds like you have a bad one that is over fueling one cyl and starving the rest for fuel resulting in backfire.The spark plug for the problem injector cyl should give you a clue which injector. Plug will be either very fuzzy with carbon and black and maybe even wet.

 

I changed the back three, they looked fine just wore out. I will check the front three tomorrow. The back three were light tan just an excessive gap.

 

I changed the front three two were easy, the last one was a pain, threads but it in now. They all looked ok but the wires have over 200,000 miles on them so they are next. The vehicle ran ok except for acceleration and hills and it took a full tank of gas to go 50 miles. I need to check the o2 sensors next as soon as I figure out how 🤔

 

If the O2 sensors are original, with those miles , the oxygen sensors are overdue for replacement.
All these things done a little at a time isn't that bad, but when we wait and get clobbered all at once it costs a bundle.
It really should be called "Programmed maintenance" not preventive maintenance.