so i've come to the conclusion that my truck has a misfire under load.

no codes whatsoever have been thrown and it's been doing it for a while.
i tried to get the truck to mis while sitting still and no luck. anyone know how to go about solving this issue?

another thing i've considered is the trans might be on its way out. is there anyway i can differentiate between the two?

the truck shakes and bucks a little between 40 and 45, calms down and then starts again at 60+. truck is a daily driver so i'd like to get this solved quick. thanks.

also, truck has 120k miles. plugs were changed around 90k and coils were done not too long ago.

 

That's a coil and that's their favorite load to misfire. I've seen this problem many times and have had it myself. Right after the shift into over-drive, they mis under load. It's called a "low grade misfire".

The only way I have force a CEL, is to push the motor when it begins to misfire. When it smooths out as RPM's increase, slow down and push it again,, -hard. That increases monitor count (Misfire monitor). As the count increase within drive-cycle it will eventually case a blinking CEL. Once they blink, you have a DTC on the KAM. The engine light will be off, but you still have the DTC in memory. It will come up with a scanner.

At times, no matter what you do, you can't get the misfire monitor to spit up a DTC. If you can't get your CEL to blink, - replace all coils to solve the problem. A entire set of coils will run you about $90.

 

BTW- Coils have to be installed right or they won't last long. They have to be protected and you don't want any dielectric grease on the spring plug connection. That's what happens allot as well. Some aren't installing them right. If their not installed right, you can fry your new coils.

 

i only put dielectric on the boot. it may have been possible for some to get on the spring since i did put a little as close to the bottom of the boot as i could.

it's been nearly a year with these coils. might have been a bad one in the bunch that is just now coming to surface. i bought these from uneek supply. i was really not looking forward to re-installing all coils.

i'll try pushing it next time i get a chance. we shall see what happens. thanks again.

 

Yea, that's all you can do, unless you take it to the dealership and they "Mode 6" it. That reveals cylinder history count regardless of a CEL or not. They can determine the faulty coil, but yea, it will be an $80 charge to do so and if they fix it, it will be another $80+ for the part with an hour charge to replace it (80-$85).

So, your kinduh stuck unless you want to spend the money at the dealership and get it done with. ?

Personally , I would purchase coils from Global Auto. I've had great luck with those. Never a bad one, but I guess their customer service sucks. I purchase the 10 packs of 508's as well. That's in case I do get a bad one, - never have yet.

 

Question on just how to do this jbrew...if you grease the inside of the boots, install the spring--install the boot over the spring--how is the best way to keep the grease off the spring ?? Been wondering about this for a while.

 

The best way to do this is with the plugs out. You apply a thin coat of dielectric on the ceramics before installing the plugs.

When you grease the entire insides of the boots, you the install the boots over the springs and onto the coils. Then pull the end of the spring past the boot ends and hit the spring with lacquer thinner or some kind of grease cutter before you install onto the plugs. This cleans the spring ends where they contact the plug. You don't want ANY grease on the contact point.

You can hold the spring with a pair of hemostats or a thin piece of metal after pulling them from the boot ends before cleaning. After cleaning the spring ends, release the spring so that it recoils back into the boots. It's now ready for install.

Boots/Coils install with a twisting motion onto the plugs. If there isn't grease on the plug ceramics, there should still be grease inside the boots at the ends. The spring connection/ contact point should be cleaned after following procedure. What I'm saying is, you can install successfully without greasing the plugs ceramics, it makes it easier is all, when you do.

 

Could be a dirty fuel filter restricting fuel under load...

 

THANK YOU for the info jbrew, much appreciated