Go Bottom

Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-01-21          150526


Hey ya'll, hope your all havin a great New Year! I will give you a fast run down of events and ask for any information you all can give me.
1999 Silverado, 4.8 vortec 8 cyl ext Cab 4wd. 190K.
New Tranny and I would like to keep her a few more years.
I used to get 18-19 highway. Things never changed: PCV )which I have but cant find right now)valve,02 sensors,MAF sensor cat convert. Truck runs great, no noticable faults with power- pick up or idle.
OK
Nov, I checked everything over and changed fluids, cleaned air filter etc. I went to deer camp and parked truck for days on end. After deer season I noticed my MPG dropped to 15-16. About Dec.15 I gets a service engine light on, I read the code and its a p171 (I think,regaurdless I know it was a ) Lean fuel condition bank 1), I clear it out. A week later I get 2 codes bank on. Lean fuel condition bank 1 and bank 2. Light goes out later. Around the end of Dec. it warms enough for me to work on truck, I decide to replace a few things (not that they need it, I just wanted to spend money and thro it out the window) My plugs were a big dollar plug along with a big dollar wire. I left the wires and changed the hotter burning plug I had in there (bosh 4 prongers) to a real close OEM plug. I changed oil and filter and fuel filter. I then hit the jack pot (or thought I did anyway) When changing the air filter, it was filled with weed material from a mouse nest formed. The box was completely filled as thick as you could imagine!!! (buisy little basturds during deer season when my truck was parked for a week). I think I found it right? I cleard the service light and for three weeks, it never came on. This week the temperature fell AGAIN back to below zero and my light came back on! Bank 1 lean fuel condition! Also, I never!!! checked fuel usage right after I had found the nest and changed plugs. Now I check fuel (a real good test, drove my son back to college Sat,600 miles in -2 deg weather) I got 13 MPG. AND 13.4PG AND 14.12 MPG !!!!
Thats the info. I was thinking about changing the 0/2 sensers (the front 2, not the back ones). and then maybe the MAF BUT the sensors are $65 eah and the MAF is $150!!!
Any sugestions? Maybe a trip to the dealer would be cheaper????? Any help at all would be apreciated!!!
Tahnk you all very much!




Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
earthwrks
Join Date: Dec 2003
Posts: 3853 Home Office in Flat Rock, Michigan
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-22          150538


Broken--how 'bout some cheese (with that whine)! LOL!
Get a diesel! I get 14.2 MPG around town pulling 15,000lb. PLUS the truck. From one side of Michigan to other (yours) side of the Lake (190 miles), I averaged 26 MPG with no load. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
DennisCTB
Join Date: Nov 1998
Posts: 2707 NorthWest NJ
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-22          150540


Nothing is cheap at the dealers, but so is guessing at what the problem is. Been there.

For such a big truck your current mileage is good, as good as my much lighter and smaller Tundra that I used to have. Are you using your own calculations or a built in oem one?

Also mileage goes down during the winter in NJ because of the crap they make the refiners put in the fuel for winter pollution. I lose about 10% in the winter because of the blend.

A restriction in the air cleaner should have made the mixture richer in the old days of a carburetor right? Do the computers and fuel injection in your truck change that principle?
....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
DennisCTB
Join Date: Nov 1998
Posts: 2707 NorthWest NJ
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-22          150541


I got poor mileage on my Honda Pilot this weekend as well on the highway I usually do better than 22MPG, I got less than 20MPG.

I think it was full load (6 passengers), and crapy winter fuel blend, cold temperatures, windy. Can anyone confirm if low temps reduce MPG? ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
kthompson
Join Date: Oct 2005
Posts: 5275 South Carolina
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-22          150543


BA, my brother as a Chevy Avalanche, I think with same engine. It has about 100,000 miles and about 2 weeks ago he told me his mileage had really dropped. No reason given. He does use dealership for all service. He told me he had noticed the mileage was really worst with certain gas, the cheaper ones with no name. By chance your station is not using Ethanol and you missed it have they?

Dennis, if you are not use to hauling more load on highway speeds that will lower your mileage (my wife's Avalon with computer will show less mileage with the two of us over just one of us), head wind can kill it and a side wind will lower MPG, with a crowd you could have been driving faster and yes mileage is worst is cold weather if not long trips. Then if you air conditioner compressor is running for the defroster that load is also in there. If you had any cargo on the roof another factor. kt ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
kwschumm
Join Date: Feb 2003
Posts: 5764 NW Oregon
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-22          150551


I mentioned this in another thread while grousing about oxygenated fuels. Chevron says their oxygenated fuel reduces mileage by 2-3% but in my truck it's more like 15%. It might not explain a 30-40% reduction, but maybe that is possible. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
1hillbilly
Join Date: Jan 2008
Posts: 10 Chicora Pennsylvania Butler County
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-01-22          150581


I am happy that you go such good mileage. My 2005 silverado 1500 with the 4.8 engine has only adveraged 14 MPG since new. I hear a lot of persons talk about poor mileage in cold weather, it has to be the gasoline. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-01-22          150592


I have alot of land 312 miles away from my house. I drive it regularily. I will fill up and zero my milage trip counter. Fill up again at around 256 miles (Osseo,Wi.) I would usually be between 13.5 gallons and 15 gallons at the re-fill up. That equals 17.0 to 18.9 mpg. I dont cheat the pump on both ends when checking milage cause it dont take much to throw a fictitious number back at you. Since my fuel gauge broke about 3 years ago, I have to zero out my trip meter every time!!!! I fill, and... I ALWAYS, fill up all the way 100 percent of the time. I have never ran out of fuel because, I know how to figure gas milage. (BTW) I will name fuels, Mobil gas gives me the best MPG. PERIOD. I can use Kwip trip and get good milage but I can also use the four finger corner station and about all the time I will be at the lower end of my average but never more than 1.5 less per gallon. This brings me back to my Service engine soon light (which came back on today). I think Im gunna bring her in. The buck and a half I spend guessing can go toward fixing it I guess. Just thought some one may have had the same experiance. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-01-22          150594


1hillbilly
Glad I have a 1999 then! BTW, my truck is stripped except for Air. I dint even have carpet, just a rubber floor. Maybe all those spendy electric features that come on most trucks use more fuel??? Try driving with out the air conditioniong on and then check it?

EW
How much was that smelly fuel U use last time U filled up??? If I had to pull my work tools behind me everyday, I would spend 10K more for a stink truck too. With the price of that shit now a day, Im glad I still have a gas truck ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
Chief
Join Date: Jul 2003
Posts: 4297 Southwest MiddleTennessee
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-23          150605


BA,

Have you tried replacing the oxygen sensor(s)? The fact that you get a lean condition code latched points toward something in this part of the system. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
Chief
Join Date: Jul 2003
Posts: 4297 Southwest MiddleTennessee
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-01-23          150606


Another item you might try after you identify the current problem is to install a set of underdrive pulleys on the engine for the crank and alternator. They free up a little hp that might save you 1 mpg give or take. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-02-03          151075


Chief
This was my first choice and it also was the first thing the guy at autozone said he thought the code could be . (Not that I put that much into the auto zone guy) but he see's alot of codes I believe. Then I thought there should of been a 02 code shouldnt there????? The 02 sensers are only around 60 bucks. Supose I could change the front ones? I never changed em? Maybe I will when the weather breaks here in a couple of days (too damm cold still) Although my codes have not come on again since the weather got above freezing again? This also wonders me? The codes started coming on when the temps dropped below freezing in Dec. Although the gas milage has been crappy since Nov.
Whats the weather by you like this week? ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
earthwrks
Join Date: Dec 2003
Posts: 3853 Home Office in Flat Rock, Michigan
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-02-03          151076


Broke: The problem you are having is pretty common to your type of Chevy. And luckily for you it is really quite easy to diagnose. My diagnosis is a loose nut. Yup! It can be on the passenger side, but more commonly it's found right behind the steering wheel.

Can it be fixed? Dunno. ; )

Who luves ya baby? How's that new skid steer treating you--mine? Pretty well, thanks! 'specially with that enclosed cab AND heat! ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
Chief
Join Date: Jul 2003
Posts: 4297 Southwest MiddleTennessee
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-02-04          151083


The weather here has been nice n wet, which is just what we badly need. With these engines, it can be difficult to diagnose what is causing the problem without hooking the engine up to an analyzer. The more I think about it, the oxygen sensors could be reading correctly. Another possible culprit could be a temperature sensor for the incoming air. On Cummins diesel it is called an IAT sensor but it can noticably effect fuel consumption as the more warm the air the less dense the oxygen in a given volume of air thus telling the computer to lean the mixture out or in your case with cold temps the more dense the oxygen in a given volume of air calling for more fuel until the engine has fully warmed up.

Another culprit could be the fuel you are burning. Depending upon the percentage of ethanol in the fuel, your fuel economy can take a nose dive. For example, fuel economy can drop by a third or more with E-85.

Just a few more ideas to consider. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
Murf
Join Date: Dec 1999
Posts: 7249 Toronto Area, Ontario, Canada
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-02-04          151085


Don't know how applicable, or even correct this is, but it makes sense.

A friend of the family has a fleet of wreckers, mostly 1 ton units that get a lot of hard service. He said they have started swapping out air filter elements on a regular basis, they keep several per truck, and change them at the start of each shift. At first I was pretty puzzled by his comment, but the more he talked, the more it made sense, and is backed up by his 'real world' product testing.

The theory is, the combination of (intake) vacuum and snow or wet spray being pulled in, and the cold / hot cycles as the engine heats up, and then cools down after shut-down, combine to draw a lot of moisture into the air filter element. As soon as this moisture hits the magic 32° temperature all that moisture turns into ice crystals. This plugs the filter and reduces the amount of air the filter allows past it.

He says that they get, on average, based on testing they did at first, between 10% & 20% better mileage by having a clean dry filter element in the truck instead of a half frozen one.

I suspect that fact that each element is blown clean with an air hose also makes a big difference, but he swears by changing the air filter element for a dry one.

He says he has also tested (using a wood workers meter) the moisture levels in the elements before and after shifts and found a huge difference in the levels.

Best of luck. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-02-10          151216


New information about this problem which may help eliminate some possibilities. It is now -2 degrees again out and all of a sudden the service engine soon light comes on again. It has not came on since the last real cold streak we had. My fuel economy is always bad but the light varies. It went off for over 2 weeks, maybe a bit more.
I have a question maybe some may know. Is there a heater for the o2 sensor? I thought I read something about this but maybe it was relating to a totally different item? Was wondering if there is a problem with a 02 heater (if one exists) if this is why when it get real cold, I then get a light? I am leaning towards biting the bullet and replacing the 02 sensors.
EW
I sure am glad I waited before buying a skidsteer. I still wont absolutely need it for anouther 1.5 years BUT wait till you see what may be coming out! I think it will fit my bill perfectly. ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
earthwrks
Join Date: Dec 2003
Posts: 3853 Home Office in Flat Rock, Michigan
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster  View my Photos  Pics

2008-02-10          151219


Broken: What are coming out with? Anything like it already being made? ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-02-11          151261


EW
Sorry, I shoulda kept quite, (no) and it may never make it out of Product Developement. Sites have been watched before for just such (exposed)info,{I can get in big doo doo} I must so I claim the fifth and must decline from further comment. Although I will talk to you as soon as I can either way. [Not that Earth Shattering anyways]for someone in the earth moving buisness but for the home owner it would be nice.
....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo



Chevy Truck bad mileage Engine Code P171

View my Photos
brokenarrow
Join Date: Jan 2004
Posts: 1288 Wisconsin
TractorPoint Premium Member -- 5 Tractors = Very Frequent Poster

2008-02-25          151677


WhooHoo!!
The latest and greatest! (Also the stupid boy in me)
I had enough so I decided to fix the damm problem. I had it narrowed down to the 02 sensers or the mass air flow senser. I actually figured it was the mass air flow but here is my story. Everything I read say's 02 senser's should be chganged at 100K, I know darn well that if I change the MAF and it cures my MPG problem along with the SES light, I will never change em SO, I decided to change all three at the same time! (Stupid) I know. Well I get half way down my dead end road and the SES light goes out! (This is looking good) I fill up 4 days ago. I drive 220 miles and use 12.56 gallons. Ahemm, that makes like 17.5mpg!!!! (Ahhh, the crowd goes nuts again) WhooHoo! I think I will keep my truck for another 190K miles!

So The bottom line here is that I changed the (2) two front 02 sensors and the MAF sensor. I had a SES light that coded lean air/fuel mix and I had milage per gallon drop from 17-19 down to 12-13mpg. My fix was to change the three items mentioned! Two hundred twenty bucks and I am back on track. Thanks to all who chimed in and gave my their opinions, I took my time and gave it alot of thought and waited for the weather and this alowed me to do the fix myself and save bucks! Thanks!!! ....


Reply to | Quote Post Reply to PostQuote Reply | Add PhotoAdd Photo


   Go Top


Share This







Member Login