Yep that's right

Hi everyone,
I used the search button but no luck

Here's my problem, I have a 1997 F250 Lariat, 300.000 km, that suddenly, burn gas like it is free. I went to the dealer, he took my $300 and change the air filter (apparently it wasn't the good model ). I suggest a O2 sensor but they said that 'no code, no need to change'; fuel pressure is good, injectors are good.
That was 3 days ago...I did 80 km and burn 1/4 of the tank already...
The truck seems running ok, no strange noise, smoke, loss of power... everything seems fine beside $100 in gas for 250 km

any idea ?
thanks guys !

 

You are running rich... it could be a number of things... it will run rich and throw a code. It might take a few tanks... but it will throw a code.

But it sounds like an emissions issue... like an o2 sensor... once it goes, it will fire a code. For now, you'd be throwing parts into it.

 

Check the engine oil level. Check the parking brake for dragging.

JMC

 

If you haven't changed your front 02's than i would recommend doing it. that is probably the cause. there wouldn't be a code if the sensor figures it is working properly. Change them you will be glad you did.

 

OK, I'll change the O2 ASAP, how many of them ? Any other smart check/change at the 300K mark ?

 

I believe there are 4 of them. I would not have any children or any people that are offended by foul language around you while you are replacing the upstream sensor on the pasenger side. After I replaced mine last summer I came to the conclusion that whoever put it in that spot at that angle deserves a kick in the crotch.
BTW when my O2 sensor died my check engine light came on and there was a code for the sensor so yours may not be bad, I would recomend that you have your PCM scanned for pending codes, if a sensor is working intermittently it will set a code but not light the check engine light.

 

Just replace the first 2 that are before the cats. the ones after the cats are there just to tell you that the cats are working properly. The first ones get lazy. They may not fail totally and throw a code but they will wear out and need to be changed. I would recommend changing your o2 sensors every time you change your plugs.

 

Do you recommend getting them at a Ford dealer or aftermarket? My truck has 140K miles and I'm still on the original O2 sensors.

 

www.rockauto.com, best price. if money is no problem, go to ford.

 

I wouldn't be to worried about where you get them from. I have Napa ones right now

 

Any sensors are fine if they are made by Bosch. That's who makes the OEM Ford sensors.

 

NGK also makes OEM Ford sensors.
Trust me, I know..

 

hey guys,

i'm in trouble again !! I changed the O2 sensor and my problem seemed fixed for a tank of gas (+400 km) but I'm back with my 200km a tank
On top of that the engine misfire after a cold night outside and I 've now a check engine light !
I don't know if these two problems are connected but I start to worry here.

Any idea of what to check ? my mechanic (as well as Ford dealer) sounds lost

Thanks for your help !

 

If you have a check engine light then you have a code. I would suggest going by any Autozone and have them put a scanner on it. It's a free service. I would also be looking at the Cats to be plugged. If you haven't changed them, it's time. Next time you have an O2 sensor you think is going bad, buy a pair of cheaters first. If the issue doesn't change, then you just saved a bunch of money. And if one goes bad, just plug in the cheater until you can fix it. If you haven't changed plugs, wires, and coils, in the last 50,000 miles, now is a good time. But pulling the code first is where you need to start.