Shudder at light throttle

[Vegasmarc21]

Can anyone tell me what shudder I have under very light throttle usually on any gear EXCEPT 1st and 2nd gear with about 1100 rpm to 1500 rpm..... Doesn't happen when I start driving when Tahoe is cold and not up to operating temperature. WOT there is no shudder at all. I have a 2011 Tahoe 5.3 V8 with hundred twenty thousand miles.

 

[PG01]

You rver clean the tb?

 

[Vegasmarc21]

You rver clean the tb?

Yes.....twice. the 1st time I was too careful, as in just the outside part, second time, I cleaned it to sparkling, brand new looking condition. I also cleaned MAF sensor 2 twice.

I was trying to clean the idle air control, but sounds crazy, I can't find it. I'm not a mechanic, but I can do basic tune ups like oil changes, radiator flushes, spark plugs, and just installed an exhaust manifold clamp on the driver's front and passenger rear which was a pain in the rear.
I was thinking the same, throttle body but the shudder only happens was vehicle is warmed up and in 3rd gear on up.... The weird thing is that it will go 2 or 3 days running smooth, then all of a sudden it comes back.

 

[PG01]

Hows trans fluid look/level? Last service?

 

[Danny3737]

Any cracked or brittle vacuum hoses?

 

[Vegasmarc21]

I bought the 2011 Tahoe 5.3 2 months ago. Checked the fluid and even had a reputable big time transmission shop here in Portland Oregon look at the transmission fluid. They said it looks fresh. I also found out through a car fax type of vin search that the transmission fluid was just changed a month before I bought it. I don't see any brittle hoses or cracks in any vacuum lines..... I'm hoping it could be a bad throttle body or throttle body sensor or pedal sensor or dirty fuel injectors... It runs great wot and idles pretty smoothly....I do have a little slack on the driver's side cv axle...2 months of this wondering what it could be..... Is it the v4 mode that makes it shudder? I did have a 2004 z71 5.3 that was so smooth.... You would think GM would be at this point building off of that, making Tahoes as good or better nowadays.... Anyone help I'm getting sick of this shudder. I want to get a tune and some nice replicas, but not until this shudder is solved....I did replace with new ngk iridium's and MSD plug wires....

 

[Meccanoble]

I was going through same mess as you trying to find this issue and still have it.

I changed the spark plugs
I got a tune to remove the v4
I already changed the tranny fluid over 6 months (15k+ miles) prior to noticing the shutter
Cleaned throttle body/MAF

Dealership thinks its torque converter or related. I would love for it to be something along the lines of throttle body but who knows.

 

[Vegasmarc21]

I was going through same mess as you trying to find this issue and still have it.

I changed the spark plugs
I got a tune to remove the v4
I already changed the tranny fluid over 6 months (15k+ miles) prior to noticing the shutter
Cleaned throttle body/MAF

Dealership thinks its torque converter or related. I would love for it to be something along the lines of throttle body but who knows.

Off the topic, what tune did you get?

 

[Vegasmarc21]

One interesting note here, though I check the transmission fluid, and although it seems brand new and not burnt, it is way over filled. The cold Mark is below the hot Mark, and when I check it cold, it's about 2in above the hot Mark..... Could this be part of the shudder at low RPM? I bought it used from a Ford dealership, so I'm thinking that a Ford Tech or whoever changed it didn't go through GM procedures.

 

[Meccanoble]

Off the topic, what tune did you get?

Vengeance Racing tune. Its a local shop in GA that works on domestic cars. They have ability to turn off the v4 so the engine mechanisms are still there but the v4 wont function. Similar to the device people plug into their car to turn it off but cheaper and more permanent.

I thought I slightly over filled mine but when I checked, it was actually a little low. When I put enough in, the shutter got better but still exists. Before, I would have to take my foot off the gas or accelerate significantly harder to make things better. Otherwise it would cause a lot of vibration from shutters. Now, you can still feel the shutter and see it in the rpm's but keeping the same pressure on gas, you can see truck fight through it and drive somewhat normally through the shutter. I changed my oil the other day and checked the tranny pan for leaks and on ramps, you can see 1 or 2 of the rear center bolts is a little wet as if there is a slight leak. I didnt want to tighten the bolts too much but may have to give them a half a turn to be safe, atleast the rear ones.

 

[Vegasmarc21]

I'm going to try lubeguard instant shudder fix and see if that helps....I hope that stuff won't harm anything in the transmission.

 

[PG01]

Snake oil....love it

 

[Meccanoble]

I'm going to try lubeguard instant shudder fix and see if that helps....I hope that stuff won't harm anything in the transmission.

What made you go this route? I'm interested but scared to do something I havent heard someone else here have success with. Looking it up now lol.

 

[Meccanoble]

That stuff has great reviews! Each package handles up to 8 qts of tranny fluid. Someone mentioned in a video the 4 speed takes 15qts. How much does the 6 speed take? I see different brands but all are shutter fix and in similar packaging.

 

[Vegasmarc21]

Well I bought the Lubeguard Tc shudder fix from auto zone today while I was talking to a customer service lady from Lubeguard 800 customer service ( thank God she was in the USA) who was very knowledgeable about transmission shudders. She said give it at least overnight to work it's way in. Got home and put it in. Took a drive and the shudder became worse! Kept driving and seems to have smoothed the shutter a little. Took another drive a little later, with no shudder, but, was driving in a little faster paced traffic, so not really anything to go off of. I'll keep you guys informed if Lubeguard helped the shudder and hopefully Lubeguard will save my sanity.

 

[Meccanoble]

Thanks For testing. Hoping for good news.

 

[swathdiver]

It would be nice to see how everything looks inside electronically. Did you tighten the torque converter bolts? Did you check the bolts and play on the u-joints?

Are the plugs gapped to .040? I think you said AFM is turned off, so no shuddering in V4? Definitely get the level right and see if you can tell what kind of fluid they put in the transmission. It is supposed to be Dexron VI.

For you fellas with Tech2s, the transmission has an oil life monitor that can only be viewed from the inside. I reckon dealers may neglect to reset them but you never know. Mine read 35% at 117k miles and I had the dealer flush and exchange the fluid and then I reset the internal monitor.

Black Bear can also tune your transmission's TCM. He might be able see things that are causing this vibration and would certainly know what to do.

 

[Vegasmarc21]

It would be nice to see how everything looks inside electronically. Did you tighten the torque converter bolts? Did you check the bolts and play on the u-joints?

Are the plugs gapped to .040? I think you said AFM is turned off, so no shuddering in V4? Definitely get the level right and see if you can tell what kind of fluid they put in the transmission. It is supposed to be Dexron VI.

For you fellas with Tech2s, the transmission has an oil life monitor that can only be viewed from the inside. I reckon dealers may neglect to reset them but you never know. Mine read 35% at 117k miles and I had the dealer flush and exchange the fluid and then I reset the internal monitor.

Black Bear can also tune your transmission's TCM. He might be able see things that are causing this vibration and would certainly know what to do.

Very good check list....you sound like a very thorough person. No I didn't check the ngk iridium's for .40 gap like I should have (I assumed ngk's are usually spot on) I'm concerned about the cylinder 8 plug because it is so hard to reach and may have not tighted it correctly) checked u joints and they are good....I put it in m5 and can make it shudder in 3 gear on up if I really lug or bog the engine. My father in law owns a auto repair shop but has been extremely busy. If this lubeguard doesn't work, it's probably not the torque converter. I'm thinking bad rear axle bearings (but why only in 3rd gear on up and at low rpms)? Going to take a test drive now. I'll see if the Lubeguard has worked it's way in.... As far as correct fluid dexron vi, I don't know what fluid is in there...maybe I should do a flush and new filter. Maybe my drive line is out of balance? Anyway, going to test drive now.....

 

[Larryjb]

I know it is a different vehicle/engine, but I had exactly the same symptoms with my 92 Mercury Grand Marquis. It was the transmission torque converter. The first time this happened to me, a complete transmission fluid flush, including draining the torque converter, corrected the problem. About 10 years after that, the shudder came back and draining the torque converter wouldn't correct it so I had to have the torque converter replaced.

Hopefully the Lubguard works. If not, you could try DrTranny Instant shudder fix. I heard it works well, but don't mix it with the Lubguard. I would try draining the torque converter and flushing the entire transmission. Then if the shudder comes back, try the DrTranny.

 

[Lightning 95]

Does it have cylinder deactivation? Mine does, and I can always feel a light shudder at light load when in goes into V-4 mode.