OK so I was driving to work this morning and I got at about 55 or 60 mph maybe a little more and I the whole truck jerked. It was strange, and I was like oh crap whats going on, then it jerked again. It did it every so often and then I stopped to grab a drink and after that for the other half of my 30 minute trip I kept it under 60 and never felt it again.

So, I'm thinking maybe water in the gas.......replace the fuel filter and try an additive?

Any ideas?

 

Did it feel like you just ran over railroad tracks? If that happens, you need a transmission service.

 

I don't know how to describe it other than just a slight jerking. It was like when your falling asleep, and your body involuntary jerks to wake you up because the brain thinks your body is dying.....I think that is called a myoclonic jerk if I remember correctly, but anyways that is what it was like.

 

the way you make it sound, its almost like something with your transmission, but im not sure. Kyle should be able to help you out more on this problem.

 

Transmission is just the word I did not want to hear.

 

Before or after the custom 4" drop? Did the blocks they put in have the correct pinion angle or are they straight blocks?

EDIT: Not trying to scare you or add more options to the mix, just a caution to you. I'd be comfortable with 2" blocks that are straight. But 3" and above I would use the ones that have the corrected pinion angle on top. I don't think these would be your cause because it would be constant, not a sudden jerk. Just tryin' to give a heads up!

 

After, it just started, it has been three days since the drop, and as far as I know they are just regular blocks, the front was more of the custom stuff. What kind of angle are they supposed to have? I had no clue about that.

 

Here is a little bit on pinion angled blocks. Basically your raising the whole rear axle up higher into the body. If the whole rear axle stays straight and the driveshaft remains at the same angle, something's gotta give. 2" (blocks) and below and it's not a big deal. 3" and above and I would recommend the blocks. They return the rear axle to a similar angle as stock to keep the angle of the driveshaft close to stock as well.

But like I said in my edit (I think you were posting at the same time as my edit), I don't think this would be the cause of a sudden jerk. It would be more consistent I would think. Either way, it'd be good to climb under there and see if your blocks are straight or angled.

If it started happening soon after your drop, I would have the installers go over everything they did with a fine-toothed comb.

 

I don't think it is anything to do with the transmission. Transmission issues will typically be seen on the tach and are quite noticable. This sounds like a very random misfire or stumble possibly caused by water in the fuel or a failing TPS (throttle position sensor). But we really need more information to know for sure.

Does it do it at a specific RPM? Or maybe at a specific throttle angle? If you have a DMM, you can probe the TPS signal wire and watch the voltage as you increase the throttle angle to wide open throttle. It should be a smooth transition from 0.5V at idle (closed throttle) to around 4.5V at WOT.

One thing is for sure, changing the fuel filter and running some ISO heat (red bottle) through the fuel system won't hurt anything.

 

Here is a little more info, on my way home today............nothing no syptoms whatsoever. I just know what speed it acte up at and that was above 60 mph, the tach was normal, and all the guages were at their norm. Can you think of anyhting else I could look for to give you more info?


Thanks for the info Kyle, I went to AUtoZOne when I saw that and picked up a fuel filter and the ISO stuff, we will see what happens I guess.