Not going into 5th gear

[Dustin L.]

So here is my problem. If i'm driving under normal conditions I have no problem but if I decide to punch it, lets say i'm in 2nd or 3rd gear, once I'm in 4th and its time to go to 5th, it won't go. I'm able to pull it out of 4th but its like it hits a wall when i'm trying to put into 5th. No grinding or anything like that. It just straight up won't go. I can't go into 6th either. Now once the RPM's drop then I can go into 5th. And like I said this is only when i'm flooring it. Is there some kind of limiter on how high the RPM's can go when shifting into certain gears or something....I'm not the greatest when it comes to knowledge about cars. Anyone have any idea whats going on because its driving me nuts!

[GXPaycheck]

I’m no pro, but it sounds like syncros.

[-Ray-]

Can you cycle through all the gears in neutral?
Try double clutching into 5th or 6th?

[zpappas]

Pardon my lack of knowledge on the GXP , but could it be in the tune or settings from GM, like they do on the Camaro and Vette, to have skip shift under certain acceleration?

[Dustin L.]

When I am in neutral I can cycle through all the gears no problem and when I am driving at just average speeds there's no problem as well. Just when I step on it. When I got the car tuned after I put on my mods the guy got rid of the skip shift. Are the syncros expensive to replace? I'm guessing you would have to get inside the transmission and i'm guessing that's probably expensive. I haven't tried double clutching it. That may work but either way I wanna find the real problem. Go idea to try for now though.

[-Ray-]

First off, have you checked the fluid? However, if it is the syncros, then the transmission has to come out.

[bracketracer]

I hate to say this Dustin L., but what you describe sounds exactly like what I experienced when I toasted the synchros in my transmission while it was still under warranty. The transmission had to come out, and the synchros had to be replaced. They weren't cheap, but I was lucky that GM paid for it. If it is the synchros, this problem will only get worse the more you drive it. My recommendation is to deal with it as soon as you can before more damage can occur.

P.S. please check your notifications. I sent you a Private Message with info on your car and questions.

Thanks!