Rough Idle/surge/delayed Shift...

bgrif005 · September 8, 2008

OK, trying to put this all together. I know there are numerous people on this forum who have posted and commented on these issues seperatly. Some people have described a delayed shift at stop lights. Some people have said that have a rough idle followed by a surge at a stop light. Are these two things connected? I see both of these problems on my truck. I have had it into the dealer 3 times now for this and they continue to say its the slip yoke and then proceed to grease it - this does nothing. This last visit (a week ago) they told me this is there last attempt to fix it, that there were no other solutions. WTF!? anyway, the problem used to not do it at every stop light, but now it is. The promblem is not worse, just more frequent. I have just learned to keep my foot firmly planted on the brakes to keep my vehicle from jumping/surging foward!

Has anyone found a fix for these problems? Has GM linked these two things togther as the same cause with 2 effects? I know that a lot of people have gone back to the dealer for these issues and sometimes you have people POST on the problem without reposting if there was a fix or solution.

My dealer seems so busy to get people in and out that it seems they don't want to dig too hard. They say they never experience it, but that they trust me that it is happening - so i appriciate that, but I still have the same problem. I have asked if the ECM or TCM needs an update or reflash...."no, thats not the problem...the TSB says its the slip yoke and this grease will help.

Zembonez · September 8, 2008

Slip yoke grease fix does work. I've used it on two of my trucks with amazing results. What I thought was a delayed shift or bump from the trans was nothing more than the yoke not sliding as designed. I fixed both of mine in the garage and it took about 10 minutes.

If this is not a possibility for you or it turns out not to be a fix, go to the dealer and make a Service Writer go for a ride with you. Show him exactly what you are experiencing. I recommend going at an off peak time (not first thing in the morning or at the end of the day when they are dealing with heavy customer traffic) so he will have time to check it out. Afterwards, you might have to drop it off another day for the fix, but you'll have somebody that witnessed the problem. It can save a lot of hair pulling in the long run.

Just my 0.02

gdpgmc · September 8, 2008

I am experiencing a similiar situation with my GMT900 (aka NBS 2007). Since the day I took delivery of the truck (March 2007) it has done the surge after coming to a stop. I have 7800 miles on it and it still does it. I haven't been back to the dealer for it (yet) and I have been following these related threads.I am not trying to be argumentative, but there is a long time delay before the surge happens after coming to a stop. In the order of 10-15 seconds and there is no audible noise or hard clunk that you can fee. The RPMs on the tach also will increase slightly at the same time as the surge. I can't see how the slip yoke is hanging up and causing the engine speed to change?

Zembonez · September 8, 2008

I am experiencing a similiar situation with my GMT900 (aka NBS 2007). Since the day I took delivery of the truck (March 2007) it has done the surge after coming to a stop. I have 7800 miles on it and it still does it. I haven't been back to the dealer for it (yet) and I have been following these related threads.I am not trying to be argumentative, but there is a long time delay before the surge happens after coming to a stop. In the order of 10-15 seconds and there is no audible noise or hard clunk that you can fee. The RPMs on the tach also will increase slightly at the same time as the surge. I can't see how the slip yoke is hanging up and causing the engine speed to change?

Not taken as argumenative at all... this is just a discussion of opinions.

My 05 Silverado did the very same thing. Sometimes I would SWEAR that somebody had bumped the rear bumper after I sat there 10 or 15 more seconds. I even looked back a few times to see if somebody had! I would not have believed that the slip yoke lube would have fixed it unless I saw it for myself. Changing load on the engine (alternator, ac, power steering) can change the idle RPM. The slight change in RPM increases line pressure in the stopped transmission. I think that is what made the slip yoke finally move and the bump was felt... not the other way around. I've heard of many trucks having this issue and I might not have believed it if I hadn't solved it TWICE on my own vehicles... so I say it may well be worth a shot.

bgrif005 · September 8, 2008

I am experiencing a similiar situation with my GMT900 (aka NBS 2007). Since the day I took delivery of the truck (March 2007) it has done the surge after coming to a stop. I have 7800 miles on it and it still does it. I haven't been back to the dealer for it (yet) and I have been following these related threads.I am not trying to be argumentative, but there is a long time delay before the surge happens after coming to a stop. In the order of 10-15 seconds and there is no audible noise or hard clunk that you can fee. The RPMs on the tach also will increase slightly at the same time as the surge. I can't see how the slip yoke is hanging up and causing the engine speed to change?

You hit the nail on the head. I don't hear a noise when it happens...there is not a clunk noise. GPROC, do you notice that a surge in RPM's occurs at the same time as the bump?Zembones, maybe it is the slip yoke. But, i have had this special grease applied twice now with nor result whatsoever! either the slip yoke is not the problem or the mechanics at my dealer can't grease for sh*t. I used to really think it was the slip yoke, but i am just not sure anymore.

khester84 · September 8, 2008

I've noticed that when i'm stopped...and then let off the brake slighlty the truck will surge/bounce a little bituntil it rolls past 5 mph...its this related to the slip yoke?? Don't mean to hijack the thread!!

bgrif005 · September 9, 2008

I've noticed that when i'm stopped...and then let off the brake slighlty the truck will surge/bounce a little bituntil it rolls past 5 mph...its this related to the slip yoke?? Don't mean to hijack the thread!!

This is what i'm trying to determine, whether or not the slip yoke is causing all of these symptoms. With the engine rpms bouncing around and surging in step with the jerk foward (feeling as if someone hit you from behind) - i just find it hard to believe that the slip yoke is the cause. But, hey, i really might be wrong...just doesn't make since to me. i know the slip yoke has been a problem in the past GM truck models and it seems that i read that most people hear a noise along witht the jerk, like a squawk or clunk. i don't think there are many, if any, GMT900 owners who are describing a noise along with the jerk. someone please correct me if my statements are inaccurate.

gdpgmc · September 9, 2008

"You hit the nail on the head. I don't hear a noise when it happens...there is not a clunk noise. GPROC, do you notice that a surge in RPM's occurs at the same time as the bump?Zembones, maybe it is the slip yoke. But, i have had this special grease applied twice now with nor result whatsoever! either the slip yoke is not the problem or the mechanics at my dealer can't grease for sh*t. I used to really think it was the slip yoke, but i am just not sure anymore. "Yes, I notice the surge in RPMs at the same time as the bump.

khester84 · September 10, 2008

Well my rpm's don't really jump around or rev up...I guess it could be the torque converter just starting to create enough pressure to make the truck move...? Who knows