BamCam

Man that sucks! What are you looking to get? From our experience all the loaners had this same issue or slightly less but it appears to be a gamble that in 5K miles your not in the same boat. My brother is looking to move away from a pickup for awhile. He feels (I would agree) that manufacturers are just trying too hard (no fault of their own) to get these bloated pigs down the road within CAFE requirements. It is a shame because the trucks are really nice otherwise.

Are you still happy with your fix? Just curious what your avg mpg is? Was it ever below 15mpg during issues? My brother's truck is now only getting 12-13mpg combined. Before his issues at around 5000 miles he could easily get 19-22mpg. He is still awaiting lemon law results so no repairs or attempts are being performed at this point.

Your story is sounding more and more like my brother's and you are going down the same rabbit hole. They too were suspecting injectors and were going to replace all but later called and said they were not. Did GM put a stop to that for some reason?...not going to cover under warranty?...we don't know. At that point is when GM field guys pull data from truck and left never to be heard from again and to date still no direction to dealer for ""fix". That is why lemon law was initiated. I hope you have better luck and wish you the best.

My brother's truck is still exhibiting this and getting worse. He has not received any updates from GM if/when the fix will be. I rode with him this past weekend and I am shocked GM allowed his truck to be returned to him. In our opinion, it is a safety issue. His is so bad at times the truck almost comes to a stop on an incline. It feels like a car with a clogged catalytic converter. Because of this, GM not being responsive & GM customer care's recommendation, he has started the lemon law proceedings. For his sake I really hope it gets done, he and his family are extremely upset with the whole experience and just want the truck gone. Sad that he traded a great running '06 Silverado in on a 57k truck that runs like garbage.

As stated above, the issue is present on the '17s and '18s on the dealer lot. So based on our experience and what they are telling us, I cannot say with any certainty it is MY and/or Trans dependent. The cold weather just makes the problem that much worse. It is still there in 50, 60, 70 degree weather. It does seem to be less as the ambient temperatures rise but this will need further validation when weather warms. He bought the truck last May and over the summer it was there but he seemed to think it was normal until 30s & 40s came and then it was obviously an issue. We feel it is programming just based on the fact that during the test drive when the tech made one slight adjustment (not sure exactly what) the truck fell flat on it's face and he quickly reset to previous. We know the tech personally and we asked if he could make it stall can he make it better. Of course, his response was..."um no...not legally". Which is completely understandable and was really just us ribbing him. Since getting the truck back my brother has been using M6 or M7 and issue is less frequent so maybe AFM related? I too have stopped driving my '17 Colorado in D on most occasions and strictly use M5 or M6 unless on highway. I have learned, that during the last day the truck was in the shop, two gentlemen from GM were present and they were downloading and taking screenshots of the ECM/TCM data. Service manager and Tech said some screens looked like the Matrix (binary code). GM cleared the truck as mechanically sound and said go ahead and return to customer. The GM rep present also had no issue offering my brother the max extended powertrain warranty but it has to go thru corporate. He is still waiting to hear what that coverage will be. It is nice to know, at least in my brother's case, GM is trying to do something and collecting as much data as possible. Will this lead to a "fix" who knows but I highly recommend anyone with similar issue have the dealer/GM look at it. The more samples they get the better it would be for all of us.

I am guessing my brother was one of the other 4! See my recent post in the below thread. HPFP was replaced as you stated. http://www.gm-trucks.com/forums/topic/208388-2017-53l8-speed-lugging-at-throttle-tip-in/?page=3

Update from my brother's '17 Sierra 8 speed. Gasoline was not the cause, once the temperature dropped again the issues came back as bad as before. So, last week he took the service manager with laptop along for another ride and they determined trans is fine, TCM parameters are normal. They started looking at fuel system and laptop showed truck running super rich and "loading" up. Never has the truck thrown a code and not one CEL during all his issues. Manager made quick adjustment and as he suspected the chuggle, hesistation was magnified and truck almost shutoff. With the data in hand, the service manager sent brother and truck home to wait for him to contact GM to decide what to do next. Monday, dealer says bring truck in we are going to change injectors and see how it goes. In the meantime, we check oil and it is 1 to 1 1/2 quarts high with gas in it! He dropped truck off Tuesday and just got word this afternoon it is ready for pickup. Result??...dealer is unable to fix the truck! Replaced HPFP for gas in oil issue, all injectors were tested and OK. No fix for bucking, GM knows about the issue but have not issued a fix. Dealer drove another '17 5.3l & '18 5.3l both are doing exact same thing. Dealer also drove two 6.2l trucks and they have it to a lesser degree. Dealer states if there ever will be a fix it could be more than a year out. GM needs to validate with EPA etc. Dealer has submitted paperwork for a component extended warranty on the motor for his truck because of this and his troubles over the last 3-4 months. As I and many others with knowledge of situation have said, this is all in GM's sub-par tunes for the 0.10 MPG gains. Got to love CAFE!!

Unfortunately yes if you want full tune ability. As of right now you/I have three options for the T87A trans. Send out to HPTuners for their unlock service, Chuck at Corvettes of Westchester offers TCM tuning (not sure of details) & lastly, Trifecta offers a tune with TCM recalibrations without unlocking. Blackbear does not offer TCM tuning and sounds like they never will for the T87A. I have been researching tuning options as well and this is not what I was hoping for. The trifecta tune has been well received over on the Colorado/Canyon forum so this may be the route I go. Downside is it's a "canned" tune, so you will not be able to tune GM torque managment parameters and this was something I was looking to do.

Got my truck back yesterday and tank was almost empty so filled at new gas station and after 50 miles it still has this performance issue. TSB was complete...new gas... issue still exist in same driving conditions prior to service. I found the below thread and I think you, my brother and myself are experiencing this. After all this I am assuming GM programming issue that will not be resolved and as stated in thread is performing "as designed". My brother is awaiting an appointment with the GM engineer for a ride along (1-2 weeks). I expect same results. I will be looking to tune my problems away with a tune or supercharger(Mallett).

Update for you. We are suspecting bad fuel, from subpar station, at this time. As stated earlier truck was going to be data logged yesterday afternoon, so my brother topped off his tank (9 gallons) at a different Sunoco station than normal before getting to dealer. The entire way from work to station and then dealer, the truck would "chuggle" on command. After driving with laptop for a few miles the chuggle started to subside and confusion set in. Keep in mind, GM was only looking at transmission data at the time, no discussions at all with fuel, and reported the truck to be mechanically sound but would be in touch after additional data review. So driving truck home my brother suddenly realizes the possibility of it not being transmission shudder but related to the fuel. At this time this is making some sense as both he and I have exclusively used 91 or 93 from this rural Sunoco station over the past 4 months. As stated earlier our driving style and commutes are identical and we both have same issues. I currently do not have my truck due to it being at dealer for CEL for evap purge solenoid going bad and what we thought was trans shudder repair. I should get truck back today and will be getting fuel at new location. This is all very frustrating.

My brother has a '17 Sierra and I have a '17 Colorado with the exact same issue. Brother's truck has had the flush done twice and a new torque converter and problem still exists. GM is involved and will be data logging truck this afternoon. His truck is actually worse and almost undriveable at this point. The more I read posts like this and others I believe his never was trans shudder but a ECM/TCM programming issue (torque management). Our driving styles are very similar and 1/2 our commute is on the same roads, so this may explain why we both have it and not that we are just unlucky. I believe the dealer was too quick to diagnose as shudder and went down the wrong path initially. I too have believed it to be shudder but now I am not convinced my "shudder/chugging" is the infamous trans shudder that is cured with flushing. I am growing concerned this will never be resolved without 3rd party tuning.

You should contact these guys. http://www.mcgaughys-suspension.com/ When I was in the market for a '14 4x4 I contacted them and they told me their '13 3/5 kit should work on a new truck as the suspension is very similar. They did not get a chance to test on a new truck yet but told me if I purchased the kit and had any problems with the kit or install they would give me a full refund. I believe the guy's name was Sean. This was 2-3 months ago so they may have had a chance to install one on a 4x4 since then. Hope this helps.

I am deciding in the next week to order or not. My dealer is telling me that GM shuts down for the whole month of December. They are saying it could be 12 weeks if ordered today!!! Is there any truth to this?