GM 5.3L Ecotec3 Engine... thoughts?

[ShinyPete]

TinTin - I hesitate to share this because I'm normally an upbeat guy, but I had a different experience with a 5.3L GM than most, and you should know my story too. We owned a 2009 GMC sierra 4x4 crew, with Z71, 3.42 LS, tow package blah blah blah. Enjoyed the truck for it's ride, features, etc., and it replaced a well loved 2003 Duramax 2500hd Crew. The 09 turned out to be the poorest truck I ever owned, and I owned it for 2 1/2 years. Sorry to be negative, but my experience with the 5.3L AFM engine was horrible. Thank goodness we didn't have our Pete then, I can't imagine how poorly it would have towed.

The person that mentioned the "Slipshift" on a 2012? Just the tip of my iceberg, and beg GM to fix that NOW. When our engine dropped cylinders, the transmission slammed on every downshift so bad it sounded like the trans was coming apart. The truck spent 6 weeks over the course of a year at the GMC dealer South of me, with GM paying for most attempts at repair and 3 or 4 rental cars. Truck was still in warranty, and they tried, but they never fixed anything. The last time it was in, with 6k miles left on powertrain 60k warranty, and the third complaint opened with GM customer care, they called me and said, no problem found, and don't bring it back. Then GM customer care said the same thing. Oh and to add insult to injury, the truck began to loose a quart of oil (loose, not drip, just GONE) every 2k miles.

So, faced with an assumed upcoming major failure, and the end of the warranty, and GM telling me, well, insert rude comment here, we traded it for a new F150 crew 2wd with a 5.0 v8 that uses all 8 cylinders thank you very much.

Oh, and the Ford handles Pete just fine. But you asked right?! Flame suit on.............

[TinTin]

I've driven my 2014 Sierra long enough- 2500 miles solo and 600 miles towing - to report on gas mileage.

2014 Sierra SLT 5.3 L , 4x4, 3.73 axle, 18" GYWrangler, crew cab, short box, tonneau, max trailering

Actual measured mileage (mostly highway miles):

Solo: 20.1 mpg (tanks vary from 19-21 mpg) Speed about 70 mph, mostly cruise. Vehicle cruises about 1700 rpm at 70 mph..

Trailering: 13.0 mpg (tanks vary from 12-14 mpg) 23 foot Airstream. Speed about 60 mph, mostly cruise. Usually in hauling mode. About 1850 rpm at 60 mph.

On board fuel computer is very accurate, transmission is smooth with no clunking, power certainly adequate for my trailer.

I'm happy and satisfied with the vehicle!!

[scamp]

Hi Bob( tin tin) glad you enjoy your new truck,I like mine alot even though the trans when cold does a funny shift ,like I said in a earlier post I think it's just a software problem and have had no other funny trans shifts problems that some other people mentioned I recognized the funny second to third gear flare up ( slip shift ) about a 200 to 400 rpm increase when it happens engine cold,it will do this about 2-4 times then it's ok normal shift ,I was concerned about this at first but as I did some maintenance on trans and changed the oil and filter I found normal color of oil and normal amount of particles on trans magnet in bottom of trans oil pan ,I know this because I'm a retired auto tech I worked on all makes and models and worked for gm and honda dealers mostly,for 33years ,on our trip to jackson center ( by the way sorry I missed you, my wife had to be back at work for Saturday and we left early Thursday 12:30 am due to a call were my daughters boyfriends father passed away)anyway on our trip to jackson center I drove 55 mph or 90 kph and with our 2012 5.3 L engine 3:42 rear end,4x4 extend a cab , we got highest 18 miles per gallon( imperial gallon)and lowest 15 mpg (imperial gallon) oh that's with regular gas 10% ethanol) and the back of the truck bed 6.5 foot was full BBQ ,bikes,gas cans ,Extra propane,generator,etc with a soft tonneau cover. Over all very pleased with my truck! If you (bob ) get a chance to drive at 90 kph with you trailer on and on level ground maybe you can publish you fuel consumption figures ,I'm curious with your engine been direct injection. And does it go into v4 operation with trans in tow haul mode? Don & Carole ( scamp)

[TinTin]

Hi Don. I'll post updated towing mileage when we get home, which should be Sunday. I haven't noticed if it goes into V4 in haul mode, I'll watch that info screen a little more in the coming days.

By the way, the data I posted are in US gallons.

We're still at JC now, the trailer should be done about noon today. It did okay on the 27 point check yesterday, needed a new head on the electric jack (cracked) and a black tank sending unit. Everything else was good. They also did the bearings yesterday.

This morning they're doing the seal tech test, and pulling the rub rail at the rear to inspect and caulk underneath.

I've been impressed with the service center people, pretty knowledgeable and thorough. If they find a fault, they solve it, even if the hours exceed their estimate.

Did the tour yesterday. Don was away, another fellow (Gary) did it. Enjoyed it, and learned a little, though I couldn't hear much of what the tour guide said. Seems to be getting busy here, maybe the spring service rush has begun. About 30 on the plant tour.

[scamp]

Hey Bob We really enjoyed our factory tour and as you said was hard to hear ( Don)even with the portable PA system , we didn't get a chance to see the airforce museum or the caves,but really enjoyed the bike museum,the food at the in between restaurant (close to i75) a walk in the town of Troy ( the sculptures have been removed ) the Neil Armstrong museum was ok,we should have gone seen the caves oh well next time ,were already thinking of a second trip next year,as we plan on buying a new airstream each year , to get warranty work done on it before selling it ( we buy in the USA then sell them in Canada a year later and break even or make a few bucks) unfortunately I discovered a few more problem with our 2012 airstream when I got back home as I washed it ,the lower chrome coloured rub rail started to flake off and one of my tire rims has started corrosion I never though this could happen on a two year old airstream, aluminum rims on cars even exposed to salt usually are corrosion free for 5 years, as for the airstream repairs on my trailer they were very good ( I'm very picky) as I'm a retired shop Forman ,shop manager at a local large honda dealer,I have seen the quality of work go down in the last 8 years or so as the baby boomers retire the younger generation on the most don't care ,don't take pride in there work , we had ( Les ) work on our trailer and were very pleased I even went into the service managers office to see Mike to let him know that ( Les) did good work ,the only disappointment I had was my front windows the curved ones were starting to discolour the aluminum part and they also were not bent properly they had bumps in them at the bottom of the curved section ,I compared them to other airstream on the lot and they were all ok but mine ,I suspect they didn't want to change them because my trailer was a month out of warrantee, oh well live and learn ! Anyways enjoy your stay in jackson center . Don and Carole ( scamp) oh forgot to mention I got axle seals in j.c. And repacked my bearing yesterday it was nice here sunny and plus 8 Celsius

[TinTin]

We left JC about 1330 this afternoon, made it to Crawfordsville Indiana fighting a 50 mph west wind.

The trailer's looking good, helped my confidence in our new unit, which was the point of our stop at JC.

We spent Sunday afternoon at the Air Force Museum. Excellent museum, particularly for aviation buffs. One day doesn't do it justice. We'll be back one day!

We had Casper working on our trailer, pretty happy with his work. Should have stopped in and spoken to the Service Manager, maybe I'll flash him an email!

[wncrasher]

Originally Posted by TinTin

We left JC about 1330 this afternoon, made it to Crawfordsville Indiana fighting a 50 mph west wind.

The trailer's looking good, helped my confidence in our new unit, which was the point of our stop at JC.

We spent Sunday afternoon at the Air Force Museum. Excellent museum, particularly for aviation buffs. One day doesn't do it justice. We'll be back one day!

We had Casper working on our trailer, pretty happy with his work. Should have stopped in and spoken to the Service Manager, maybe I'll flash him an email!

Check your manual about tow/haul mode. On my 2011 Silverado, it says not to use it unless you are over 75% of the trucks haul capacity. You could get better mileage by not using it, if not needed.

[scamp]

I m going to check that out ,I remember years ago people towing in overdrive they would burn up top gear clutch , I think the 6 speed trans has two over drives gears 5 th and 6th .

[scamp]

Bob glad all went well at j.c. ,I'm going to have to go back as we have more things to visit also,have a safe trip back home. Don and Carole (scamp)

[dkottum]

Originally Posted by wncrasher

Check your manual about tow/haul mode. On my 2011 Silverado, it says not to use it unless you are over 75% of the trucks haul capacity. You could get better mileage by not using it, if not needed.

Can't speak for Chev, but our 2006 Tundra and 2012 Ram 5.7 always did better on fuel economy in tow haul mode (overdrive automatically off) when towing. This was because the transmission would shift down and up consistently to cope with most grade changes and headwinds by getting enough engine rpm to be in an adequate torque range.

So it really wasn't about % of the truck's haul capacity, it was about road characteristics and weather conditions. It could do okay in overdrive on fairly level roads but I soon learned that is not the norm.

[scamp]

Ok I checked the owners manual ,G.M. says tow haul mode is designed to be most effective when the vehicle and trailer combined weight is at least 75% of the vehicles gross combined weight rating( gcwr). Also in the tow haul mode the trans hangs on to the gear longer so less up and down shifts,less wear on clutches or bands and you also get engine braking :the trans will downshift to assist in slowing down , this is done by vehicle speed ,throttle position, and brake pedal position (on or off),also manifold absolute pressure(map )sensor (engine load)input to the power control module ( PCM,fuel and trans computer) the manual states there is no harm in using tow haul mode if the load is lighter then 75% of the combine vehicle weight! Operation the vehicle in tow haul mode when lightly loaded or with no trailer at all will cause no damage,however ,there is no benefit to the selection of tow haul when the vehicle is unloaded.such a selection when unloaded May result in unpleasant engine and transmission driving characteristics and reduced fuel economy tow haul is only recommended when pulling a heavy trailer or large heavy load. Well I'm going to have to try with it off and see what kind of fuel economy I get and then make my decision on whether to select it or not!i guess it also depends on road conditions hills etc..

[TinTin]

Haul mode was effective through the Appalachians, slightly higher RPM, other than that little noticeable difference with the exception of very effective engine braking on steeper downgrades. I think I'll keep using it in hilly country even though I'm probably well below 75% GCWR. Probably won't use haul mode until the east slopes of the Rockies now.

[TinTin]

Home Sweet Home,,, safe and sound. Just under 2400 miles of towing now, in some crazy weather much of the way. Spring is coming in like a lion I guess. Towing average didn't maintain the 13 mpg I reported earlier, a better number is probably 11.5 mpg. The wind is the big factor, fair winds added 2 mpg. One day, we fought a 40 mph head and side wind all day, my average for the tankful went down to 9 mpg.

Enough of the data, I'm happy with the vehicle, comfortable, quiet, enough power. Can't ask for more.

[A W Warn]

I appreciate you sharing your experiences with your new truck. I am having similar experiences with mine regarding solo fuel mileage. I cannot report on towing yet. I have not towed except once, a very short tow. The computer on my truck gives slightly lower mileage than I measure/calculate. I calculated 22.3 mpg on one tank, my best, running solo at 55-60 mph with at tailwind. Usually I get just under 20 mpg highway and around 16 mpg around town. I have a little over 4,000 miles on my truck now.
I hope to get in a few short towing trips this spring. Then I'm planning to go out west this summer, at least 6,000 miles round trip. Your post of your experience in the mountains makes me feel a lot better about taking my truck on a very long trip with little towing before.
Thank you!

[scamp]

Hey Bob glad you made it back safely ,boy that wind really cut your fuel economy, but glad your happy with your truck , I'm a little worried about my truck as there are some 5.3L engines affected in 2012 for the oil consumption problems. So far so good !

Don and Carole (scamp)

[ghaynes755]

Adding my experience. 2014 GMC Sierra 1500 5.3L Ecotec, 3.73 axle, Propride pulling a 25 FC RB. CAT scale weights Truck (Full Fuel, driver) 6820 and trailer 5100, this is with the PP engaged.

Two long trips so far. Approx 2000 miles from Colonial to Denver. And just returned from a trip to Las Vegas, 2200 miles the long way down through Albuquerque and across.

The 5.3L does a great job. Overall MPG was 11.23, towing at 64mph. 6% grades I was able to stay at 55-60mph no problem. Acceleration onto the highway was fine. Stayed in tow haul mode the entire time. The 2014 manual also mentions tow haul for primary use when the overall vehicle/trailer weight is more than 75% of the GCWR. Mine is about 79.5%.

Had the same experience going through the mountains of PA on the way home from Colonial. Averaged 9.63. Guessing that it was lower due to very heavy (30-40mph) head winds from eastern Kansas until we got home.

Downside to the Sierra is weight capability. With full tank of gas, me the wife and dog there is only about 60# left for additional cargo. Don't trust the published numbers. They appear to be for a stripped down truck. Start adding what most would consider normal stuff and my truck is nearly 500# heavier. Items like a sunroof, 20" tires and rims, bed liner, bed rollup cover quickly eat into the available weight. Throw on the tongue weight of the FC and nothing left.

So I have a 2500HD on order. Didn't know, and had no plans for a larger trailer, when I got the Sierra 1500. But the AS bug struck. With the types of driving conditions we have in Colorado, one minute nice, next ice, snow, sleet, rain, wind I just don't feel comfortable cutting into the design safety margins for overall weight carrying on the truck.

Bottom line, smaller trailer, less tongue weight (no Propride) then the Sierra 1500 is a great choice and more than capable of getting it done. FYI general around town mixed mileage I get 18+. Highway not towing 20-22mpg.