97 V6 SOHC cool air intake

The easiest (and least expensive) way to get better mileage is to retrain your right foot. IMO, the next best is to fix the exhaust; a larger diameter pipe will do wonders. Problem is, cat back is the best that can be done in most cases, unless you want to spend a lot of $$. Intake can do some good, especially after the exhaust is fixed. However, intake mods do best at high RPMs, and when high power is needed, exactly the times when mileage goes down anyway. IOW, intake mods are better done for power, not economy.

Most of the ideas people have about intake mods and economy come from the days of carbs. With today's feedback electronic fuel injection, the engine will do its very best to supply the right air-fuel ratio, no matter what the intake's condition (within limits, of course). Adding a cold air intake won't do much, because the engine will still provide the same air/fuel ratio to achieve the desired exhaust O2 readings. This means that any advantages of the colder air will be overcome by the EFI altering the fuel delivery to keep the exhaust right.

The reason the exhaust mods work is because the mods are downstream of the O2 sensors, and they work to make the engine work less; less parasitic losses means the engine puts out less power for the same road speed, meaning less fuel used. Cold air intake doesn't do the same thing; it attempts to supply more oxygen to a fixed air/fuel delivery system, thus making the air/fuel mixture leaner. The EFI foils this attempt, by using feedback from the O2 sensors to maintain the air/fuel ratio. Other intake mods attempt to reduce pumping losses, but without making the exhaust bigger, the results of intake mods on pumping losses is minimal, IME. Adding something like a K&N filter is, IMO, counter-productive. They only flow more air (if at all) at high RPMs and under heavy loads. Fine for racing, but for street use, pretty minimal. At the same time, in order to flow more air, they also pass more fine dirt. Again, fine for racing, where the engine will be rebuilt at fairly low mileage, but for street use (where we hope to get 100k miles plus), this can not be good.

My opinion is this: first, train that right foot to go a lot easier. Then, fix the exhaust; a good cat back system can be good for an

*honest* 5% or so in better mileage. Then, if you've got the cash, fix the intake, but don't expect too much here. And have your bull$hit detectors in place when listening to others tell you about the extra power/mileage they got from doing a mod; the seat-of-the-pants dyno is extremely unreliable!

Something to consider: the makers already have to put an intake & exhaust on the vehicle. Why don't they make them better? Obviously, cost is one reason; another is one that's not considered often: noise. Both the intake & exhaust are designed to be a reasonable compromise between efficiency & noise. Mods will usually make either one noiser. While we may be willing to put up with the noise for more economy/power, the average buyer isn't. (And, those outside the vehicle sould be considered, too; Nascar level exhaust noise isn't even legal on the street!) So the intake/exhaust are designed with more restriction (and less noise) than would be optimal for power/economy.

Good luck!

Thanks Bill, I didn't think I had a heavy right foot. I just had a new engine put in because of a bent cam shaft and I am still only getting on ave 14-15MPG Highway and about 12 in the city, and I was thinking that was kind of low, and wanted to fix that a bit. Is this low of gas mileage typical for an explorer?

That seems quite a bit low on the mpg scale.

I have a 97 XLT SOHC V6 and have consistently gotten 16+ mpg in combination city/highway. On pure highway trips it will be in the 18 to 20 range depending on the terrain and the speed of traffic. Moving at 80 mph and it is definitely around 18 mph.

It now has 127,000 on the original engine. The mpg figures have been consistent over the life of the vehicle.

Hope that adds perspective.

Dave

engine put in because of a bent cam shaft and I am still only getting on ave

14-15MPG Highway and about 12 in the city, and I was thinking that was kind of low, and wanted to fix that a bit. Is this low of gas mileage typical for an explorer? >

put in because of a bent cam shaft and I am still only getting on ave

14-15MPG Highway and about 12 in the city, and I was thinking that was kind of low, and wanted to fix that a bit. Is this low of gas mileage typical for an explorer?

No one thinks they have a heavy foot! :-) My Explorer is a '92 Sport 4X2, and my wife drives it, and she doesn't check mileage, so maybe the others here could answer that better.

Here's what I would do if I thought the mileage was low: take it to a shop that can do a good evaluation of the engine to make sure it's operating right. It'll cost a few bucks, but it could also find any problems. Just adding an intake would not do this, obvoulsy.

What bent the camshaft?

No one really new for sure...It was in the shop for over 4 months with a number of mechanics looking at it and small engine people as well. It turned out that the 97 explorer cam shaft was made weak or on a friday, but Ford had a real low key recal(not publically announced but if contacted they would tell you about it) on a certain number of 97's, I had an inside source to help me find that out and got the new engine from it.

The last vehicle I ever conciously checked gas mileage on was an '88 Mustang

5.0 (must've been maybe my second or third midlife crisis)..... this car was stupid.... My loving bride could easily pull 24.... 25 miles per Imperial gallon yet the best I could ever get was maybe 8....... ..... talk about wierd, huh? Even something as simple as the music we listen to can affect our mileage..... there are a lot of people that unconciously move there feet in time to the beat.... yep, the right foot, too... not to mention music that leaves us feeling either agressive or laid back.

There are ever so many other things that can affect our fuel consumption... like Bill, I have little idea of what one would consider 'normal' since I drive those vehicles that I want to drive and am prepared to pay the price. Back in carburettor days, it was easy to show that a carb overhaul would pay for itself in short order in gasoline savings. On our modern vehicles, we are faced with the stark reality that something as simple as unplugging and reconnecting a "dirty" connector can cure some pretty big sins....... all our sensors work on 4.5 volts nominal..... doesn't take much corrosion to upset the apple cart.

I would suggest that the original poster reset the Keep Alive Memory (remove both battery cables and touch them together) and drive the car normally for a few days. If the problem persists, he might have the PCM polled to determine where the fuel trims are running...... with a fresh motor, we would expect to see long term fuel trims close to zero.

Important to remember that lean mixtures will equal poor fuel economy (tough to swallow, but still the truth) and there are many, many more things that can drive mixtures lean than those that will drive them rich. Vacuum leaks or other sources of "unauthorized air" and dirty sensing elements in the MAF are two big causes of lean mixtures. To a much lesser extent, "lazy" HO2s can also affect our mileage but my experience shows these to be relatively rare compared to other concerns.

Jim Warman snipped-for-privacy@telusplanet.net