bad gas mileage
 

I have a 1999 B3000. Its gas mileage dropped from 26 to 15 miles per gallon. I suspect the mass flow sensor or O2 sensor. It has new spark plugs and wires, clean K&N air filter. Question is, is there a way to check the sensors for failure?

RE: bad gas mileage
 

I have had the same problem with my truck. I was caught off guard when my gas mileage on my b2500 just fell drastically. still searching to find the answer.

RE: bad gas mileage
 

Hard to believe there were no other problem indicators. More exhaust smoke, sluggishness,
any noises coming from the engine , tinging etc . ? If not then o2 sensor may be the easiest n cheapest to try for a start. It's not hard to do.

RE: bad gas mileage
 

DaveP

I have an '89 b2200 with all the symptoms you mentioned: exhaust smoke, sluggishness, valve lashing. I will replace the o2 sensor immediately. I bought the vehicle with 171K. Noticed immediately a shop rag stuffed in the emmissions hose. I thought I had been shot in center mass when the rag came out (shot with a rag bullet and lots of black suet). I suspected a blocked catalytic converter... but have not investigated it yet. Any help or forum references will be appreciated.

RE: bad gas mileage
 

i have a 2001 b3000 and i was wondering where the 02 censor is located ..i get about 12-14 mpg changed eveything except wires..still looking for a good set of wires and to replace the o2 censor

RE: bad gas mileage
 

yours should have either two or four o2 sensors bobolink. it will either have one on each exhaustbank before the first catalytic converter or one on each catalytic converter and one after on each exhaust bank. anything with a maf sensor will have at least two.

RE: bad gas mileage
 

Just sort of an FYI, if that is the oiled cariety of K&N that will screw with the MAF... Here's what happens, small amounts of oil form the filter will blow back through the intake and accumulate on the hot wire in the maf.. This in turn insulates the wire and the maf will actually be measuring less air than is actually coming into the engine... Normally this will causelean conditions..
Although the computer will adjust the A/F mix to compensate if it sees a lean condition at the O2 sensors.. This will not always set off the MILL as the error is small.. But once again the computer will start dumping extra fuel to the engine to compensate.. This has been known to cause all kinds of odd issues on varuious Ford and Mazda products.. Some have tried cleaning the MAF with varying results... I know Ford release a bulletin about contaminated MAF sensors... Dunno of Mazda did or not...

O2 sensors would be the best and cheaper place to start... According to manufacturer specs they are only good for about 100K miles anyhow... The O2 sensors BEFORE the cats, are the ones that are crucial to fuel mixture as the ones behind the carts are mostly for monitoring how well the cat converter is working... IF you have access to a scan tool that allows you to veiw engine data you can get a real good look at what the MAF and O2 sensors are doing...