my truck is in great shape, EXCEPT that i have had to replace the ignition coils twice in the past year and it needs it again i think. one year ago i took it in because it was missing really bad between 45-55mph. the mechanic said it was my coils and even though it was not possible (according to him) to find the exact wrong one he guessed and replaced one. of course this didnt work. after paying him $200 to replace one and not getting it done. i went on Ebay and bought 8 NON OEM ignition coils for $80 and put them in myself. this fixed the problem or seemed to for about 6 months. in June it did it again. so i did it again. Now for the third time in les than a year it is missing bewteen 45-55mph and i am tired of replacing the stupid things. the way i see it there are three possiblities:
1) its not the ignition coils and just coincidenal that replacing them fixes it temporarily
2) i am getting crappy coils.
3) im doing it wrong.

Any ideas?

 

Have Autozone pull codes for free. If you have your old coils, most may be good. Non OEM are often made in China and don't last.

 

i had advanced auto look at it and it didnt have any codes and the engine light wasnt on. he said to have them put a "scanner" on it or an oscilliscope. does this make any sense?

 

Autozone coils and napa coils are good coils. Cheaper than oem. You can change the yourself. It easy. 1 bolt 1 plug and pull up.

Now start your truck and let it idle. Unplug each coil ONE at a time. As you unplug one listen and feel for the change in the way it idles/runs. If there's no change when you unplug one then there is the bad/dead coil. Replace it. Moisture is the leading cause of failure. The spring like conductor that runs from the coil to the plug (inside the rubber boot) rusts and this is what causes them to fail. The current will not flow properly threw rust.

Also as stated china coils are junk. Don't buy them. Also there's no need in replacing (a good ) coil. Some might last forever. I bet the one that are giving you trouble are in the back of the engine. That's where excess water that dint drain properly off you window cowl get saturated.

 

I purchased a set of Global Automotive coils off of e bay and have had great success with them. When was the last time you replaced the plugs. A bad plug can destroy a coil.

 

these are from global automotive (origin unknown). the first thing i had done last year was the plugs. i hadnt heard that about the ones in back though. i will probably try replacing those first. i actually have 2 new ones laying in the shop.

 

Sounds like you have had a lot of moisture where you live. Take the coils & boots off, & fill them with die-electric grease. This should slow down your problem, if not fix it. I purchased a code reader from Harbor Freight for 99.00. It stays in the truck. When a code finally pops the Check Engine light on, I pull the code then the coil!

 

UPDATE:

I have never gotten around to replacing the coils because the problem was so random that it never became a priority. So fast forward a month or so, I pull into church and there is steam coming out from under the hood. I can't find a leak, so I have a different mechanic look at it. He can't find a leaky hose either but he had to put in ALOT of antifreeze. He asked if it was missing and i said yes (told story about coils). He thinks its a head gasket or some other god awful problem. could this have been my problem all along and not the coils? If so whats this going to cost roughly to fix?

 

You need to find out where the steam was coming from. It could be from the intake manifold crossover. 2001 should have the composite manifold. They are known to leak.

 

ADDITIONAL UPDATE:

got it back from the shop. Couldnt find a refrigerant leak anywhere. Dont know how or where all the fluid went. gonna keep a closer eye on it (never checked in 2 years). When he pulled #8 coil (the one indicated by the computer) the dielectric grease had turned hard and black. Im thinking this may be my problem. ive used that same grease from advance auto on both coil changes. It was thick and grey in the beginning. the grease he used was a GM product and looked like petroluem jelly. Hopefully this solves it, but im betting more of them go out soon as a result of teh faulty grease.