Shudder at light throttle

[89Suburban]

I agree sounds like lock up converter shudder. I had this in a 700R4 unit and just unplugged it. Not sure how it can be bypassed or not in these newer transmissions. If you add extra transmission cooling it should help keep the temps down disabling the lockup feature.

 

[Vegasmarc21]

When I bought it 2 months ago... It already had a trans cooler in it....maybe wrong transmission fluid? I have tried 92 ethanol free octane. But I'll try it again to see if it still shudders.

 

[Vegasmarc21]

I agree sounds like lock up converter shudder. I had this in a 700R4 unit and just unplugged it. Not sure how it can be bypassed or not in these newer transmissions. If you add extra transmission cooling it should help keep the temps down disabling the lockup feature.

If there is a fuse I can pull.... I'll do it to stop the shudder....

 

[89Suburban]

If there is a fuse I can pull.... I'll do it to stop the shudder....

I hear ya bro and I understand your frustration. I am old school and new to these era of trucks and their quirks so it is a learning process for me as well.

 

[Meccanoble]

I'm just going to ask if you've tried the simplest thing, running some high octane gas and see if it still does it?

Yes, I used high octane from chevron and used chevron injector cleaner and same issues.

 

[Meccanoble]

BTW my trans temp never gets that high, always under 180. This shudder happens when tranny is cool. It seems to happen around 2nd -6th gear with light pressure on gas around 1500-2500 rpm (cruising speeds).

 

[Vegasmarc21]

Maybe this is my problem? Just a brake switch....

http://www.tahoeyukonforum.com/threads/transmission-shifting-weird-issue.22829/

 

[Meccanoble]

You might be onto something. My cruise control hasn't worked since I owned my truck and the common issue is that brake switch that attaches to brake pedal. I question why issue wasnt always there but maybe truck is telling me to change it. Your Cruise control working?

 

[Meccanoble]

I think this is the part needed, though Amazon doesnt say it will fit Tahoe but fits other GMC's with similar years....

https://www.amazon.com/ACDelco-D158...d=1508939959&sr=1-2&keywords=brake+switch#Ask

 

[Vegasmarc21]

Hey guys, last night I went to a car wash where you spray wash your car with a high pressure washer and and sprayed brake cleaner to all calipers and discs and pressure washed them clean. Then today, I went underneath and checked the emergency brake line at the rear of the Tahoe and it looked like it was hung up and really tight so I loosen It Up by wiggling it and loosened it up and got it free I also check the connection to the PCM I believe is back there underneath the spare tire and sprayed a whole bunch of electrical cleaner and checked if the wiring harness to the PCM was all the way in and it was loose so I made sure it was nice and snug and since I was down there I sprayed every electrical connector clean cuz they all were really dirty I drove it and wow what a difference with like throttle it was smooth all the way through. Another thing I did was check the drive shaft the front drive shaft kind of wiggled so I turned it until it I couldn't move it up and down and then I put a hose clamp on the rear drive shaft kind of like adding a weight to it, I felt around and it felt like a low spot so that's where I put the hose clamp the screw was like on the low spot side if you can imagine that, but anyway whatever I did it seems like the Tahoe was running smooth even at the highest temperature at 180 degrees. I'll drive it some more and fill you in if it's not doing the shutter anymore. The main thing I was trying to accomplish was making sure that the brake calipers and the emergency brake was not binding or holding up the Tahoe on light acceleration. Because those emergency brake lines can get rusty, and on light acceleration I'm thinking any binding on the brake could be fighting the light acceleration and even Tc clutches and make the vehicle shudder. So far is pretty smooth even on a warm day and transmission temperature at 180 degrees where the normal shudder would start at around 155 degrees on transmission temp on up. So check your e brake lines, there are 2(left and right rear) and electrical connections underneath.

 

[Meccanoble]

Any progress is good progress, though I fear the improvements could be in your head, still hoping for progress. Time will tell. Your logic makes sense so I'm rooting for ya!

 

[Vegasmarc21]

I drove all day and I'm still driving and no shudder. I always had a feeling that this Tahoe is being held back by something like the brakes dragging but they weren't the only thing was that I found underneath was Rusty e brake cables so I soak them in WD40 today earlier and maybe also that dr. tranny shudder fix is starting to really work now, who knows but it's not really shuddering anymore.

 

[89Suburban]

I drove all day and I'm still driving and no shudder. I always had a feeling that this Tahoe is being held back by something like the brakes dragging but they weren't the only thing was that I found underneath was Rusty e brake cables so I soak them in WD40 today earlier and maybe also that dr. tranny shudder fix is starting to really work now, who knows but it's not really shuddering anymore.

Ok fingers crossed for you.

 

[Vegasmarc21]

Drove about an hour today, and feeling good about how well it drives. Anyone who thinks it's a torque converter shudder should check for brakes that drag and either find a way to adjust or replace them and try Dr Tranny shudder fix. I used 2 2ounce tubes. I'll report back if I feel any shudders.... But so far around town ( City driving) I'm up to exactly 15.0 City driving mpg was about 12.8 to 13 around town. I believe that 15.0 mpg is supposed to be what Chevy says it's supposed to be. Thanks for every one's support on here. Hope you guys that have shuddering get it solved without too much out of pocket.

 

[Meccanoble]

Its so hard to accept it as brakes fixed because you would feel the issue at lower speeds. If I'm crawling around the neighborhood, I dont think the issue happens. You have to be going a moderate speed to feel the shudder and the slower you go, the bigger the impact should be of brake issue. We would also smell more than usual braking or feel an abnormal amount of heat if it was that consistent. I have had sticky calipers before and there is a noticeable difference in heat and smell. It seems like that Dr Tranny may have did the trick (or maybe I'm just hoping)

I'm very happy for you and appreciate the testing. I bought that brake switch for cheap on amazon and though I dont think it will fix the shudder, it has the potential of fixing 2 issues (cruise control doesnt work). Will definitely go the dr tranny route next and still look forward to more updates from you.

How did you put the dr tranny? You put on 2 different occassions or back to back? How many miles would you say you put on the truck since you first added?

 

[Vegasmarc21]

Its so hard to accept it as brakes fixed because you would feel the issue at lower speeds. If I'm crawling around the neighborhood, I dont think the issue happens. You have to be going a moderate speed to feel the shudder and the slower you go, the bigger the impact should be of brake issue. We would also smell more than usual braking or feel an abnormal amount of heat if it was that consistent. I have had sticky calipers before and there is a noticeable difference in heat and smell. It seems like that Dr Tranny may have did the trick (or maybe I'm just hoping)

I'm very happy for you and appreciate the testing. I bought that brake switch for cheap on amazon and though I dont think it will fix the shudder, it has the potential of fixing 2 issues (cruise control doesnt work). Will definitely go the dr tranny route next and still look forward to more updates from you.

How did you put the dr tranny? You put on 2 different occassions or back to back? How many miles would you say you put on the truck since you first added?

I put in (1) 2 ounce tube, then about 3 days later added another 2 ounce tube..try 1 first
I also got a new brake switch. My crusie control works now.

 

[Meccanoble]

I put in (1) 2 ounce tube, then about 3 days later added another 2 ounce tube..try 1 first
I also got a new brake switch. My crusie control works now.

My brake switch just came in yesterday and I installed too. I owned the truck for over a year now and never had working cruise control. My initial drive after change, I felt shudder like usual. I then tested cruise control successfully and shudder seemed to have gone away or gotten way better. I'm still testing and making sure its gone but definitely going the dr tranny route if its not.

Some things I noticed when I changed my switch out:
1) Original switch didnt seem to be fully installed. You could see the green marks on the screw before you even start to unscrew.
2) After cleaning my throttle body, I had to do a relearn process because if I revved, my rpm's would stick, especially if I got it over 3k rpm. Even after the learning process, it would not stick under 1500 rpm but it would still stick a little if I got it over 2500 rpm. After changing out this switch, no sticking at all, back to normal like before I cleaned throttle.

 

[89Suburban]

2) After cleaning my throttle body, I had to do a relearn process because if I revved, my rpm's would stick, especially if I got it over 3k rpm. Even after the learning process, it would not stick under 1500 rpm but it would still stick a little if I got it over 2500 rpm. After changing out this switch, no sticking at all, back to normal like before I cleaned throttle.

That is amazing to me, I had to go to the shop and get mine forced to relearn the idle.

 

[Vegasmarc21]

I took my MSD wires because I read that they're not good for electronic fuel-injected engines I went back to the AC Delco s and made sure all the spark plugs are tight and man what a difference Tahoe accelerates so crisp and smooth right now.

 

[Meccanoble]

I just went for more driving yesterday and though acceleration is better/smoother, i still can still create the shudder. Its harder to create than before but still exists. Sometimes I hear these cracks and creeks so was a little worried about a bad u joint as someone else confirmed this caused shudders while driving. Will check on that first then dr tranny here I come!