Spartan Tuned & jerking real bad

[gregw338]

I have been Spartan tuned now for 35k miles. For the last year now when ever I am pulling a load and accelerating between 50 - 65 mph the truck jerks real bad as if I am pumping the throttle. Once I get above 60 - 65 mph it smooths out. When ever it does it I have to get out of the throttle and ease back into real easy until I get 60 - 65 mph. It does it when I manually throttle it or even in cruise control. It does it on all tunes. Anyone else experiencing this?

[08stroker250]

It is throttle tip-in, basically touchy throttle. What tune are you pulling a load with?

[gregw338]

I have tried all the tunes from 210 tow to 275 and I get the same thing, even if the cruise control is engaged. It used to not do it.

[Ipkyss]

My truck does the same thing towing 250 and up tunes. What makes no sense is it seems to get worse the longer you leave the tune on the truck.

[08stroker250]

Originally Posted by gregw338

I have tried all the tunes from 210 tow to 275 and I get the same thing, even if the cruise control is engaged. It used to not do it.

When was the last time you changed your fuel filters?

[gregw338]

Every other oil change

[sjl2725]

I've experienced the same thing running the 250, especially when I'm running in Tow/Haul mode. The TC locks up in a lower gear (5?) around 40-45mph and if your foot bounces from hitting a bump or something, with such a sensitive pedal, the truck jerks, causing your foot to bouce again, causing the truck to jerk, causing your foot to bounce, etc.... The rhythm is just right to make the truck do silly things. Its not hard to do on purpose either. Best thing to do when it happens, is just take your foot totally off the long skinny pedal on the right.

Not sure if this is the problem the OP is talking about, but it sounds like it to me.

For me, it happens without a trailer too. As I said, especially when in tow/haul mode. TC locked in the gear before OD.

[gregw338]

It does it with the cruise control accelerating as well. I can be accelerating very smoothly with cruise control or manually and once I get between the speeds ranging from 55 - 65 mph it starts jerking very badly. Once you get above 60 - 65 it stops. Usually I have to get off the throttle or kick out the cruise and it usually takes me 2 -3 tries to get above 65 mph without it jerking real bad.

[TwinTurboStroker]

Tagged

[boostd6.4]

Yes, and be prepared to replace the intermediate input shaft!

I am on my 4th trans, and 3rd suncoast with the Spartan tunes in 29,000 miles....

YMMV!~

Mike

Originally Posted by gregw338

I have been Spartan tuned now for 35k miles. For the last year now when ever I am pulling a load and accelerating between 50 - 65 mph the truck jerks real bad as if I am pumping the throttle. Once I get above 60 - 65 mph it smooths out. When ever it does it I have to get out of the throttle and ease back into real easy until I get 60 - 65 mph. It does it when I manually throttle it or even in cruise control. It does it on all tunes. Anyone else experiencing this?