UPDATE:I was the orginal poster I have regular 35 mile and 90 mile drives. I still am getting 12mpg @70mph on the freeway. The engine works a bit harder than it should, when accellerating. or getting back up to speed. It only goes into V4 mode downhill and coasting. However, on two trips, I someone got good performance and got 20mpg on my last 25 miles. The engine worked easier and V4 mode was abundant. All in the same exact drive. Getting 13mpg for most, then 21 on last 90 miles. And it was fairly similar landscape the entire drive, fairly flat. On my last trip, I was stuck getting poor mpg, then did an italian tune up and finally got it to go into v4 for some of the trip. Got 20mpg for a little bit, but then now back to poor mpg. ***** Dealer and I think its a coked up engine. It seems like the interminant performance supports our theory. Where there could be some carbon floating around or sticking up the valves still. Next step is for dealer to do their own BG induction cleaning.
dgrover13 replied to Jerricat's topic in 2014 / 2015 / 2016 / 2017 / 2018 Silverado & Sierra Issues, Troubleshooting, & Recalls/Service BulletinsLets gert back to the actual topic. Please use a different thread to discuss small MPG variables. Jerricats original post is an issue of 5 or more below the state highway of 22MPG. I am in same situation, except worse. I have a stock 2014 5.3 and used to get 22mpg but am all of a sudden getting 14mpg. Dealership; currently has no answers and we have tried everything. Where are we supposed to go? I have full bumper to bumper warranty. Here is my thread http://www.gm-trucks.com/forums/topic/195512-sudden-loss-of-fuel-economy-2014-chevy-silverado-53-lt-dropped-7mpg/
UPDATE: I got 13 mpg on the 300 mile ride home from chicago. Now I think its the emergency or parking brake producing drag. I have tried to disengage, rengage, disengage different times, but I feel like there is drag at highway speeds. The e brake does work when engaged. Is that possible? For the e-brake to cause drag, even though it is disengaged? Could it be too tight and some sort of drag on the caliper? No smoke, no vibration.
UPDATE: Today I am back to poor mpg now getting 14mph on highway at 65mph. On a 300 mile road trip from chicago to minneapolis. This is bizzare. After the BG induction cleaning on Friday, I took a test drive for 30 miles freeway and got 20mpg. Same route leaving today and Im getting 14 mpg. its much warmer today 50 degrees F ???
Coby7, what monitor/tuner setup do you have. I might look into that. UPDATE: Issue seems to have been mitigated, good news. Yesterday I had the BG Induction air intake cleaning through the throttle body. 150 dollar service. Didnt drive it last night. Today after some suggestions. I looked at the ebrake and it appeared to have been fully disengaged.Regardless I engaged and disengaged the Ebrake fully. I never use it and it. I then just drove 35 miles and reported 20.5mpg on the last 25mile screen. Back to what I would consider normal!! It was either the ebrake or the induction cleaning. I can say that the ebrake has not been engaged by me since owing thr vehicle. I never felt any brake drag either. I think it was this induction cleaning. Thoughts? Ill definitly have the cats looked at anyways.
i engaged and disengaged the e brake just now. Do not use really ever. Even if I have it fully disengaged could it still be catching ot dragging?
Dealer doesnt think its brakes because we would see visible smoking etc. what are we looking for on the brakes?
My dealer and the third party who just did my BG Induction cleaning, have not mentioned the cats yet. and we have had hour long conversations trying to think about anything and everything. My guess is the dealer is saying, there are no codes or sensors telling us this, so it must not be it. Should I bring it to an exhaust shop and have them take a look at the cat? appreciate all the input. I have been all over this forum this morning and these threads turninto everyone offering what they get for mpg. I dont want that to happen here, its not relevant. Thank you for keeping the troubleshooting going!!!
Top tier...I dont have loyalties and fill up all over. In my area top tier is sold by holiday and super america gas stations. Have tried two different oils over past months. Full synthetic and also a blended ow-20. currently have dexos ow-20 the dealership put in. @65 mph on my gauges it states I am getting qbout 15mpg. I can hand calculate and it is accurate. I used to get over 500 miles per tank and now getting about 390 per tank, approximatley.
Ihave put fuel injection cleaner through twice to no affect. Does not do any good for direct injection. I brought it in to a third party today to do an induction cleaning through the air intake. well see if it does any good. Can you elaborate on the possible exhaust issues? I am trying to get my dealership to think outside the box.
Recently (started three months ago) - I have noticed a sudden loss of fuel economy in my truck. I drive 500 miles a week ALL highway. I have gone through 2 winters on it (bought with 20k miles and now has 70k miles). In september 2016 - I noticed my highway milage dropping. I used to get 21-22mpg on my 170 mile commute (all highway 70mph). It performed like this since I bought. I started seeing 17-18mpg highway, and now I get no better than 15mpg highway. My average over 50k miles driving was 20mpg My average over last 3 months and 4000 miles is 14.5mpg While on the freeway at 70mpg - it gets 14-15mpg. This is very frustrating because for past two months I have been troubleshooting with my dealership. I have extended bumper to bumper and full drivetrain warranty - none of which covers this issue!!! They can't tell me whats wrong with it and seem unable to diagnose the cause. We have tried the following: -Put different stock tires on the vehicle and drove for two weeks, no difference -Put a MAF sensor from a different (new) silverado and drove for two weeks - no difference -Tested for fuel consuption - no excessive use of oil (very little to none being burnt) -Oil changes - no difference -New stock airfilter and clean MAF sensor - no difference -I use only top tier gas and oil -No tire wear visible -Fuel trims appear to be good -No diagnostic codes showing up I know there are many variables for fuel economy, but we have look at everything we could and have ruled out most everything. The dealership is of no help and says GM has no documention on this issue elsewhere. I have talked with many auto professionals and they all say this sounds bizarre or offer up that I have a crap engine. Regardless I have full bumper to bumper/drive train warranty and its of no use!!!! Does anyone offer up what I should take for next steps? I mean, I used to own a 1971 Chevy C10 3 on the tree, that got better mpg than my 2014 Silverado. Its rather unbelievable Where do I go? Who can properly diagnose the issue? Any help appreciated! Thank you! -Darren
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