Fish Bite/Chuggle

[TRG]

On 11/8/2017 at 1:06 PM, Scuba78 said:

Yes, i too had those issues but with Black Bear they changed the TCM as well and in my opinion it drives how i would drive a manual.  it holds the gear it needs instead of the one it should be in on the highway!

Wondering if you can provide an update on the BB tune now that you've had it for a few months.  Fish bite/chuggle issues still a thing of the past?  Are you still happy with the tune?

[Scuba78]

1 hour ago, TRG said:

Wondering if you can provide an update on the BB tune now that you've had it for a few months.  Fish bite/chuggle issues still a thing of the past?  Are you still happy with the tune?

It has been night and day with the truck. It drives so much better. I have now added a cat back exhaust and had it returned for that and removed AFM. The change from 8 to for always had a funny kick. It is now even smoother. Best thing I have done to the truck I actually enjoy driving it. 

[grizz_wi]

Ill be making appointment for this issue hopefully next week, my 2016 never did it, but this 17 is terrible. 

[TRG]

24 minutes ago, Scuba78 said:

It has been night and day with the truck. It drives so much better. I have now added a cat back exhaust and had it returned for that and removed AFM. The change from 8 to for always had a funny kick. It is now even smoother. Best thing I have done to the truck I actually enjoy driving it. 

Great to hear - thanks for the update!  I'm close to pulling the trigger on my 2018.  I could maybe live with the horrendous shift points, but the fishbite issue is not something I'm going to live with.  It even does it in cruise control.  Encouraging to hear that the BB tune addressed those issues for you, as they seem very similar to what my truck does.

[Scuba78]

On 2/6/2018 at 5:49 AM, SGS_Z71 said:

I have a post going through the same crap you went through, and am considering trading in or tuning.  Can you report back if you are still happy with the tune?  I just spend 3 hours yesterday driving through the hills of Kentucky/Tennessee yesterday on I75, and it chuggled on every dang hill.  I wanted to push it off a cliff.  Would appreciate your feedback on the tune and any more information relative to such.

 

thanks!

after exhausting every avenue with GM, BBP was the best to deal with and have addressed my issue.  I was very confident from the start all these issues were programming flaws.  After their tune the truck drives very smooth and is a lot more responsive.  VERY VERY happy with the results.  Such a shame GM would not back their own product. 

[SGS_Z71]

2 hours ago, Scuba78 said:

after exhausting every avenue with GM, BBP was the best to deal with and have addressed my issue.  I was very confident from the start all these issues were programming flaws.  After their tune the truck drives very smooth and is a lot more responsive.  VERY VERY happy with the results.  Such a shame GM would not back their own product. 

Good news!  I would consider if not for the items below....

 

Mine, I’m entering a battle with GM.  On the third repair, they replaced all 8 fuel injectors due to extreme pressure differences/drop on a balance test, truck drove perfect for 1000 miles,  now the condition is back.  I have an open case with GM, and have engaged with an attorney for lemon law buy back. It has spent 30 days in the shop, and is in for repair #4 right now.  They don’t know what to do, and have datalogged it for Gm to review.  I’m getting the feeling they are going to say operating within design parameters, which is crap.  Hoping to get out of the truck within 45-60 days as I will not tow my camper with it like this.

[Matt Gordon]

Is it equipped with the M5U 8 speed trans?

[SGS_Z71]

On 4/5/2018 at 9:26 PM, Matt Gordon said:

Is it equipped with the M5U 8 speed trans?

Yes, mine is an 8 speed.  I don’t think I am dealing with any trans issues though.  GM field service engineers have been trying to figure it out for 22 days now.   I’m on day 46 total for this issue.  I heard they had an identical truck there and were comparing data between the two as of last Wednesday.  I can’t move forward on my lemon law until they “fix” it.  I’m guessing that if I haven’t heard that this is “normal” yet, then they actually have an issue they can’t figure out.

[Philly462]

I found a solution and created an account for this post...  I bought a brand new 2017 Silverado 5.3 6 speed, kept it stock, immediately noticed the chuggle or stammer/bucking up hills.  My commute consists of mostly uphills and I found I could mitigate the problem if I hammered the throttle more than usual.  I figured it was fuel delivery or throttle position.  I tried tuning programs to no avail.  Finally after 20,000 miles, and reading the forums, I found something that would fit behind the accelerator pedal -  a pack of large sized sticky notes.  Put the whole pack behind the accelerator pedal assembly.  The pedal assembly is made of plastic and flexes as you depress the pedal, causing a difference in how the throttle plate should open and how much air is delivered into the intake.  It causes the computer to think it’s being starved.  This should be fixed by GM.  I have the pack of sticky notes installed for 3 days and my truck no longer stammers and drives brand new.  I just feel bad for all the components that were starved for fuel and air this whole time I’ve owned the truck.  I plan on contacting GM customer care and my dealer since I’ve had a reference number established.  The transmission reflash is unnecessary.

[ram1067]

49 minutes ago, Philly462 said:

I found a solution and created an account for this post...  I bought a brand new 2017 Silverado 5.3 6 speed, kept it stock, immediately noticed the chuggle or stammer/bucking up hills.  My commute consists of mostly uphills and I found I could mitigate the problem if I hammered the throttle more than usual.  I figured it was fuel delivery or throttle position.  I tried tuning programs to no avail.  Finally after 20,000 miles, and reading the forums, I found something that would fit behind the accelerator pedal -  a pack of large sized sticky notes.  Put the whole pack behind the accelerator pedal assembly.  The pedal assembly is made of plastic and flexes as you depress the pedal, causing a difference in how the throttle plate should open and how much air is delivered into the intake.  It causes the computer to think it’s being starved.  This should be fixed by GM.  I have the pack of sticky notes installed for 3 days and my truck no longer stammers and drives brand new.  I just feel bad for all the components that were starved for fuel and air this whole time I’ve owned the truck.  I plan on contacting GM customer care and my dealer since I’ve had a reference number established.  The transmission reflash is unnecessary.

 Interesting! i love to see some picture of this mod..... i also deal with all these issues also i work for a university and driving a round campus is a  bitch 

damn chevy searches for what gear to be in 25-40 mph is the worst!

[Philly462]

21 minutes ago, ram1067 said:

 Interesting! i love to see some picture of this mod..... i also deal with all these issues also i work for a university and driving a round campus is a  bitch 

damn chevy searches for what gear to be in 25-40 mph is the worst!

 

[batman900]

I did the pedal flex solution long ago and it did nothing for the chuggle accelerating up hills. I have an incline on-ramp both coming and going to work.

[Pearl2017]

For the flexing pedal the long discussed and IMO easiest or best solution is to get a $.29 paint stick from Aco hardware and use it as a shim. As far as starving for fuel and causing the chuggle that is not correct. It doesn't matter how much the pedal bracket flexes the fuel and so AFR the engine receives is completely unrelated to that flexing.

 

The chuggle is the torque converter clutch not operating smoothly/correctly as it is supposed to smoothly slip x% while cruising. Stomping on the gas pedal the TCC is ordered to lock up and stop slipping thus the chuggle stops.

[Chevyexpress3500]

I bought a new 2019 Chevy Express 3500 with a 6.0 L Vortec motor and with the 6 speed automatic transmission. I experienced the chuggles or the transmission studder but didn't know what it was until I did some research and saw these forums. I took it to the dealer and they told me it was the transmission learning how I drive and it will slow down when under load to protect the motor. I couldn't accept that and had to test drive it with the service rep, the technician, the lead technician, the lead service rep, and then with a special GM tech engineer. They all agreed there is a problem. First they replaced the ECU and that did not fix anything. Then they replaced the torque converter and flushed the ATF and that fixed the problem. Hope this helps someone dealing with the same issue! I was dreading bringing it to the dealer because there was no service engine light with a code for them to work with. Reading everyone's struggles also made it seem like it would be a long painful process to work with the dealers service department. Flush your ATF first and if that doesn't fix it then replace your torque converter!!

[Chevyexpress3500]

I bought a new 2019 Chevy Express 3500 with a 6.0 L Vortec motor and with the 6 speed automatic transmission. I experienced the chuggles or the transmission studder but didn't know what it was until I did some research and saw these forums. I took it to the dealer and they told me it was the transmission learning how I drive and it will slow down when under load to protect the motor. I couldn't accept that and had to test drive it with the service rep, the technician, the lead technician, the lead service rep, and then with a special GM tech engineer. They all agreed there is a problem. First they replaced the ECU and that did not fix anything. Then they replaced the torque converter and flushed the ATF and that fixed the problem. Hope this helps someone dealing with the same issue! I was dreading bringing it to the dealer because there was no service engine light with a code for them to work with. Reading everyone's struggles also made it seem like it would be a long painful process to work with the dealers service department. Flush your ATF first and if that doesn't fix it then replace your torque converter!!