Need more advice on fuel economy

[LennyinKansas]

I've replaced the fuel pressure regulator, thermostat, coolant temperature sensor, and throttle position sensor. I have noticed no improvement in fuel economy. I noticed a lot better acceleration after I replaced the throttle position sensor, but that has disappeared. I'm not sure where to turn next. I can literally smell fuel when it is idling. I think the fuel smell is coming from the exhaust. This is a '91 Explorer XL with the 4.0L pushrod V6. I'm tired of spending money with no better results. Someone please help me.

 

[02BLK_Limited]

A generic set of recommendations for fuel economy -

1. Increase your tire pressure to 36-38 PSI cold.

2. Replace your Fuel Filter and Air Filter. After you take off the fuel filter, knock the inlet end of it against something and watch all the black/brown debris flow out.

3. Alternatively, swap air filter/box for less restrictive Cold Air Intake system.

4. Switch your spark plugs for some Denso Iridium's. Make sure the gap is correct. A larger gap will increase power, but increase the chance of spark blowout. Consequently, a smaller gap reduces power.

5. Last, but should really be first since it makes the most difference. Replace your front Oxygen sensors.

The front 02's are used to control the air/fuel ratio, and over time they will lose precision. This results in decreased gas mileage.

Non-typical results from this, yours will vary - just swapped 02 sensors on a friend's 03 F150 6-cyl, 117k miles. Drives a few hundred miles a week, all city driving, and went from three fill-ups a week to One.

 

[Joe Dirt]

Usually a FPR is bad if you smell fuel in the exhaust. Have you changed plugs and wires? Are there any codes?

What is your current MPG, and what are you trying to get to, and how aggressively do you drive the truck?

 

[2000StreetRod]

synthetic oils

Switching to synthetic oils will improve fuel economy - especially in the winter. Start with the thickest (axles) and then the engine. Mercon V is semi-synthetic so switching to full synthetic ATF will not help much.

 

[LennyinKansas]

Usually a FPR is bad if you smell fuel in the exhaust. Have you changed plugs and wires? Are there any codes?

What is your current MPG, and what are you trying to get to, and how aggressively do you drive the truck?

I was told iridium plugs, so I will change those, wires, and do the front O2 sensor at the same time. If the check engine light comes on, it does so later on down the road. It doesn't come on when I start up and idle. I'm pretty sure I smell fuel in the exhaust, but I already changed the fpr. I get a sound that almost sounds like backfiring, but it's inside the exhaust system. It sounds like small booms, but the sound doesn't come out the tailpipe. It's not like an Uncle Buck backfire. My current mpg is about 10. Two years ago it went from 20 to 10 and I haven't been able to get it back since.

 

[Joe Dirt]

Honestly- plugs are a touchy subject. 95% of people that end up installing anything besides Motorcraft or Autolite plugs into an Ex/Ranger around here will inevitably change back shortly due to poor running, idling, fouling, or mileage issues. Of course, there are exceptions to the rule, but for some reason, our vintage vehicles don't seem to like anything but Moto/Auto's in them.

You might consider wires- mine was exhibiting that same sound, and one of the wires had been burnt by a cracked manifold and was arcing.

Also- if you're doing O2's, I know recently there have been incidents where people using the Bosch universal O2's sold at the auto parts places have had codes showing up and some running issues clear up when they use the specific Motorcraft O2's for their rides. I just ordered 2 fronts from RockAuto, they also offer a forum discount.

 

[Roadrunner777]

I'm on the same trek of mileage. I would suggest cleaning the MAF. It is easy and not expensive to do other than a can of MAF cleaner (O'rielly's $7) and you will need a special tool bit to remove it (T-20 security bit). Good instructions on other threads, feel free to PM me, I just did this last week.

 

[Joe Dirt]

Roadrunner is right- not a bad idea to spray off the MAF.

RR- I wouldn't post up how much $$ you've saved, someone might send this link: CLICK

 

[LennyinKansas]

Is RockAuto a website?

 

[Joe Dirt]

yes- rockauto.com and they also offer a forum discount...

http://www.explorerforum.com/forums/showthread.php?t=299559

 

[Roadrunner777]

Roadrunner is right- not a bad idea to spray off the MAF.

RR- I wouldn't post up how much $$ you've saved, someone might send this link: CLICK

Oh I know. I'd be elite now but I donated to the recent memorial. I'm applying for elite on payday Friday.

 

[Joe Dirt]

I know- that's why I was teasing...

 

[FIND]

have your catalytic converter tested.

 

[LennyinKansas]

I see 2 part numbers on rockauto for front oxygen sensor. How do I know which one is the right one?

 

[LennyinKansas]

Good news

Even though I was advised to get the motorcraft O2 sensor, I got the Bosch one instead b/c I wanted to get going today while the weather was nice and I saved some money too. I changed it out, the plugs with the autolite iridium plugs and bosch plug wires. I'm happy to say I don't have the "booming" sound in the exhaust and as I took it for a test drive I noticed it has plenty of pep. I just fueled it up tonight and will report on fuel economy when I can.

Thanks for the advice fellow explorers. I couldn't have made it this far without you.

 

[Roadrunner777]

Definitely post your results, I might be right behind you on the Oxygen sensors.

Thanks!

 

[LennyinKansas]

Great news

I just calculated my fuel economy with my last fillup and I averaged 18.4 mpg on my last tankful.

 

[Roadrunner777]

That rocks! On the Bosch sensors, iridium plugs and wires... ok, I'm going to get in line.

 

[SwaintaN]

I see 2 part numbers on rockauto for front oxygen sensor. How do I know which one is the right one?

anyone know what the number for the o2 sensors are for moto on RockAuto?