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Showing results for tags '8l90'.
Found 9 results
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Not sure if this has made rounds on this forum yet, but it was brought to my attention at work as we have a 2016 5.3/A8 in for this concern right now (we've done them in the past but its been a month or two). I've highlighted in red the big change, GM is no longer replacing converters based on their findings on returned warranty units as it can still come right back. The triple flush has been dropped for now, just a flush and re-evaluate. It does appear they must be on to something that is a better fix as they are working on one to be released Q1 2019. Looks like they will continue to only flush/fill them for now. This does apply to ALL 8 speed applications, both 8L45 and 8L90, EXCLUDING the new T1 1500 trucks. Stay tuned...
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113,****** miles on my truck. Transmission shifts okay. Had the GM service update done with Mobil fluid at about 30,000 miles. Looking to do a pan and filter fluid change this fall and considering some upgrades. Has anyone else done things such as a shift kit, deeper pan, or the transmission cooler bypass valve? What did you do? Which brands did you use?
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Hey guys, I did the thermal bypass conversion to active by pass on my 2018 8L90. Did a step by step video because I hadn’t seen anybody do an actual full replacement video nor had I seen one on a 8 speed. Trans runs about 45 degrees cooler now. Check it out and let me know what you think. It’s the exact same procedure on 6 speeds just mounts different on the transmission.- 17 replies
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My 2019 Sierra with 12,00 miles under warranty was diagnosed by the dealership. Was told the valve body need replacement that was 7 days ago now I’m being told a replace valve body is not available and they don’t have an eta for the part. Primary issue is the torque converter clutch disengages every 5-10 seconds at highway speed, in town it is much worse. Secondary problem torque converter clutch disengages the vehicle shimmies also at low speeds has a harsh shift.
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First post, been a lurker for 3 yrs...2017 High Country w/ 101K. Lost 6,7,8, gears and truck wont shift past 5th at all. Similar symptoms to others, hard hesitation then super high RPMs (low gear limp mode). Dealer inspects and says fluid is so gummed up the valve body, solenoids and some other sh*t is "stuck" and there is metal everywhere. Yep, had the torque converter issue at 30K, with dealer flush. $5K for a new trans with a better warranty than the stock, 3yr/100K...wtf. Apparently any "updates" GM has made will be in this shiny turd of a sh*t show. Anyway...after this disaster, I'm in prevention mode...new fluid after the first 10K, then every 20k (trans, diffs, transfer). Oil every 5k, this 8L90 sucks azz.
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I have a 2017 Chevy Silverado 4x4 5.3l V8 with the 8 speed transmission. I already flushed out my transmission and filled it back up with the Mobil 1™ Synthetic LV ATF HP blue label. The question is, do i also use the HP fluid for my transfer case? Or do i need to use just a standard ATF fluid instead. I cant seem to find a straight answer on this. The owners manual states to use DEXRON®-VI Automatic Transmission Fluid. Would using regular ATF in the transfer case and HP ATF in the transmission cause any issues? Thanks in advance! -
Earlier in the week my check engine light came on and I saw the P0700 and P0711 which lead me to Transmission Fluid Sensor issues and people having to replace them. I started monitoring the sensor and noticed it didn't fail like most other people but it takes an awful long time to warm up only peaking at 150F whereas previously it seemed to always be near 200. It took about 45 minutes of driving to get into the 140's and only passed 150F after another hour of driving after that. As I learned the thermostat is only supposed to open up at 192F so I believe mine is stuck open. I will see if the dealer will give this under warranty but I'm curious, anyone do thermostat deletes and regret it? From what I read, the TCM wants 200F or close to it for better shifts and this is why the thermostat is there in the first place. On the other hand, living in a warmer climate where it doesn't usually get below 40-50F, could leaving this thermostat open extend the transmission life?
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I got the dreaded P0700 & P0711 on Monday on a 2015 GMC Yukon Denali. Cleared the code and it came back. MIL hasn't iluminated yet so I'm waiting on another drive cycle before I schedule an appointment with the dealer. In the meantime I wanted to understand the conditions of P0711. GM has a great PDF but I can't quite understand it. https://gsi.ext.gm.com/gmspo/mode6/pdf/2015/15OBDG08A Transmission Diagnostics.pdf I don't quite understand how to apply the table to the conditions. Further to add confusion, my scan tool is reading -40F for TFT although in tow mode my transmission temp reading hovers between 125 and 150. I did watch it once and see it dip to 100 flat from 125-150 for a brief moment so I imagine its just a flaky sensor but I'm more curious about what triggers this based on those conditions.
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As many truck and SUV owners know, the performance of the transmission is a big part in how confident you feel behind the wheel. While only a single part in a complex powertrain, the transmission is the glue that links an engine to the road. When the transmission hesitates, the entire vehicle’s performance suffers. A great vehicle needs an equally great transmission. After only a few minutes behind the wheel it became obvious that shifts are quicker and smoother than the past generation 6-speed. Having two more gears allows the engine to stay in the sweet spot of the RPM range more often. Tip into the throttle and with no drama the 8L90 quickly snaps to the right gear. However, the most noticeable change is how well shifts are managed by the faster next generation transmission controller. Dependable and crisp transmission performance is a benefit in any situation. A slight bump in fuel economy is the icing on the cake, allowing for a +1mpg bump in fuel economy. Under full throttle we found gear changes effortless, quick, and solid. Under light throttle we could barely notice the vehicle had shifted at all. Where the past generation 6-speed sometimes gets confused or doesn't shift as cleanly as we’d like, the new 8-speed was always seemed on point. Unfortunately, we're slightly surprised to see that manual shifting with the 8-speed hasn't changed. Commands to select a specific gear using the shifter stalk are still only a suggestion, with the transmission controller having a final say. In our short test, shift requests sometimes took seconds if the truck didn't agree with the gear we requested. We drove an 8L90 equipped 2015 Sierra Denali and Yukon Denali on urban streets during rush hour. We did not get an opportunity to measure fuel economy. While only available with the 420-horsepower 6.2L EcoTec V8 during model-year 2015, expect this 8-speed to be available in the rest of the full-size truck and SUV line in the near future. When we have an extended amount of time with another 8-speed truck we will report back with fuel economy figures and more driving impressions.
