I recently noticed a serious decrease in gas mileage, and whenever I really hammer on it, I get a horrible backfire right before it shifts.

I was wondering if my Air/Fuel ratio would cause that.

I don't have any O2 sensors, so that's what I'm leaning towards.


Would that be the place to start?

Thanks!

It certainly couldn't hurt. I'd check the codes for a close 2nd.

Thanks, Ogeechee for the quick reply.

I'll go code fishing tomorrow.

Right now I'm just wondering if I've caused any damage.

I didn't realize I posted it so quick, haha.

Seriously doubt you hurt anything, tho.

Thanks again.

Do you know how many O2 sensors there are?

I can't remember and it's too dark to get up under the beast right now.

The 2 immediate things that came to mind when I read this was 1) A badly stretched timing chain and 2) A sticky valve. Not diagnosing the problem but these are the things that come to mind right away that could cause that.

The 96 has three, one on each side of the y-pipe and on just past the second cat.

Your gonna need to put them sensors back on. The computer reads the exhaust info at the first two sensors in the pipe and then whats coming out after the cats and determines if the engine is too rich or too lean and adjusts for it. Without those sensors your just confusing the computer. it probably wants to richen it up because it doesent "see" any pollutants from the first sensor or second. The backfiring is probably just unburnt fuel and that could also be why your mileage dropped.

Thanks Yardape fore the suggestion.
I'm planning on getting a cam kit that includes a new timing chain and all the like, so we'll see what happens.



Thanks, I remembered the first two, the ones where they connect where my headers are.
Just couldn't remember if there were anymore.


Thanks BB33 that's what I was thinking. I'll be heading to the muffler shop during lunch time tomorrow to get that taken care of... I don't like going through a tank in two weeks... no matter how cheap gas is right now. And I really don't like backfiring while it shifts... makes the Bronco look bad.

a tank in 2 weeks......must be nice

Ha ha ha...

I take it you don't get quite that far.

60 milies a day.......lucky if i get all 5 days out of it

Wow... that's a lot of gas.

I do a maximum of 15 a day... 30 on weekends.

my last job i did a half mile total everyday..........round trip......i got laid off from that.......my walet has been hurting ever since

Sounds like it was sweet. lol.

I live 2.3 miles from work and I loose a lot of gas by being "that guy" that has to jump off the line as quick as I can.
It's fun, and the beast will throw you back in your seat lol.
Everyone else just thinks I'm an ass ha ha ha.

lol......why do you think i stopped owning a mustang.......i was always that guy......especially when the little hondas decided to challenge me

Ha ha ha... I know what you mean lol.

All these new trucks pull up next to me with their cat back exhaust, thinking they're bad ass... and then I roar the ole' 351 a couple of times with my dumped exhaust and long tubes... it shuts em up... and if it doesn't... the fact that I spank them whenever we get off the red does.

Ahhh... so much fun owning something of value.

nothing makes me feel more at home then my bronco lol

I am taking the advanced engine class at my comunnity college and all the kids there seem to have hondas or nissans, you'd think 19 and 20 year olds would stop playing with zipzaps by that age, So sad.

dude im almost 23.....and most of the guys my age are still trying to squezze power out of that little 4 banger........come on......build a real motor not a paper wieght

haha reading this makes me think of me and my girlfriend... i've almost 100% converted her to ford power! haha she's got a nissan 300 zx which i will admit is fun to slam through the gears sometimes but nothing like listening to a ford roar haha. we're taking both trucks out today and going to TRY to get one of them stuck haha. i dont think we will but its going to make for a fun day and hopefully her conversion will be complete by the end of the day. i hate workin on that nissan lol.

Well, got two of the three O2's put back on... and guess what...?

Still happening.

I didn't get the third on there because really, there's no point... I don't have any cats... so it'd be useless.

I'm going to change all my plugs and plug wires and do a small tune up before I dive into anything else.

I pulled codes... didn't give anything good... in fact... nothing at all... other than the EVAP code.

But I wasn't using a very good scanner so it's probably not too accurate.

I had a spark plug wire come off last time I went mudding, so I might have blown another one.

I haven't checked yet... it's just a guess. I'll get out there tomorrow and take a look at them.

Thanks for everyone who posted a reply!