Hey guys my truck has been jerking a little bit and making a metal sounding clank...it's only when I get it into boost if I'm just cruising on the freeway it's fine no matter what my speed is but as soon as I start building boost it starts jerking and make the metal sounding noise. I can push thru it and it builds boost all the way thru. If I let off the gas to stop the boost it's fine. Also the rpm changes slightly with the jerking until i let off the gas. Any ideas what could be happening? It's on a speed density tune and was running fine for the past 2 or 3 months. I've changed spark plugs and gapped them at 28. Still have the same issue. No codes are being thrown either.

 

Still sounds like a misfire to me.

Can you log all 8 cylinders to see if you can catch a misfire happening even though it doesnt throw a code?

Or you could get it to misfire and start applying the brake to keep it in the sweet spot and wait for a misfire to pop up.

 

I can do a hp tuners log later on after work. I tried the brake thing to see if I got a pop but it just stopped jerking. I would think if it was a misfire it would go it all the time not just in boost I could be wrong tho.

 

Sounds like the torque converter to me...

 

Thats kinda where it sounds like its coming from. You think thats something that would show on a hp tuner log?

 

If you log input rpm, or torque converter clutch signal it should tell you. If the electrical signal is not there, it may be an internal leak in the trans.

 

Ok I will check it out later. Thanks for your input! It's been bugging me lol

 

I'm gonna second the tq converter. Might wanna drop the pan if you haven't changed your fluid in a while.

 

Trans pan? It hasn't been changed since installed tq converter it's been about 40k

 

Yes transpan. With that many miles I would change fluid and filter.