Gas Mileage

[rmwilson]

I am getting dismal fuel milage I have a 2000 GMC envoy - its more or less a jimmy/ blazer just with the first year envoy kite (trim) , I was getting 14/ l per 100kms (there is 4 liters per gallon and 100 kms = 60 miles) now its gone to close to 16 and 17 L per 100 .. - its brutal ... I just recently did new plugs, air filter (stock) and cleaned my PCV valve. I then ran a fuel injector cleaner and now its even worse. Initially they plugs got me down to 12L /100 kms, but that only lasted for a couple weeks.

Could it be a blown O2 sensor, a blocked MAS (mass air sensor), or what any ideas? Is there a exhaust gas regular on these 4.3 votec motors?

Any tips on howe to improve fuel milage is greatly appreciated.

Thanks

Ryan

[blazes9395]

How is the truck running in general? Is it getting to operating temperature? Could be a lazy O2 sensor, since its getting colder outside, that doesn't help either. If you have a scanner, get it on there and see what the temp is at when warm, take a look at the O2 sensor readings etc, etc.

[rmwilson]

generally speaking it is running well- it has no rough idle, starts instantly, cruises fine. it has about 140,000 kms on it give or take 80,000 miles... its generally in good shape bone stock no after market anything ...


I just has a rad flush done last week as i could hear air in my heater core.. in fact again i hear air in the heater core and I put a brand new rad cap on the day of the flush. Temperature wise the water temp gauge in the car says just a hair under 100,

i do not have a scanner... do one those ones from an auto parts store work the ones that can tell you engine codes? (OBD II scanner) ....how do you check O2 sensors rather than just buying and gusssing ... How many are there.. ???
In canada we have to have emission testing and i just went for one in Sept. I can tell you the readings from that will that help - it shows i think 4 exhaust gases, dixodide, monoxides, and i think two other emissions gasses.

Thanks for all the help.

Ryan

[blazes9395]

I know all about the emissions testing here in Ontario, I use to, when it was first implemented back in '98-'99 be a registered clean air tech. What a scam it was back then. It has generally been getting better since then, becoming more meaningful. I honestly don't know if Canadian Tire's brand that they sell (Equous or something like that) actually are capable of real time on board display. I purchased mine in Michigan, as I travel down there on a regular basis.

You have to have a capable scanner to be able to see what the O2 sensor readings are to have a good idea of whether the sensor is going bad or not. Anything other then that and you are guessing.

[rmwilson]

Sounds interesting ...I did not know you could get units that measure data on the fly ... do you have a brand name of yours? Or where to get it ? I go quite often to the USA...

what fuel milage should I be getting on HWY, crusing at 65-70 mph...


Ryan

[muzzy1maniac]

From what I gather you were getting about 16.7mpg(14l per 100km). That's not too far off for cold weather. I'd say you should be getting 18-20 mpg in the cold. Your numbers confuse me a bit. The easiest way to show your mileage is in Kms per liter. Fill your tank and reset the trip odometer. Drive through the tank(not topping off the tank or anything) and refil when you're down to 1/4 of the tank or less. Now divide your kms driven by the liters you filled. Post that number for a good comparison.

As a reference my 98 would get me up to 24 mpg in the summer on some flat highway driving. That should come out to something like 10.3kms per l? No? I have conversions! LOL!

[blazes9395]

The unit I have is an AutoXRay. It has an upgrade to have the avaliable ability to read real time on-board diagnostic readings. It has saved me tons of money over the years.

[rmwilson]

I drive the same style daily not hard on the throttle some stop and goa little bit, but i fill at the exact same pump and do the same drive every week .. been monitoring gas milage a lot .. as my fuel gauge has not worked for 2 years. I have the on board computer that tells me liters used as well i reset the trip every fill up.... I also confirm that at the pump of how many litres i put in. Every week I fill up with 60L and I get 380- 400kms at MOST. = 6.3 km/ litre. not that great at all .. hell i had a v8 chevy and it would get 10 km/s per litre.