WAI? thermostatic control valve, etc.
 

Hello all.
About two weeks ago (i'm in school, so haven't had the time to look it up) I went out to my 1994 Ford Explorer (4.0L V6 Auto) to rig up a warm air intake (or hot air intake... not sure of the difference.

Well, I found the cold air intake, and looking at it from under the vehicle I followed it back to the air filter box to try and find a place to disconnect it (takes cold air from the front of the vehicle, between the front grill and headlight, not in the engine compartment). While looking, I discovered that the explorer already has an air intake tube running from the exhaust manifold to the air intake, in conjunction with the cold air intake.

I looked up info online, and apparently in these early engines, they used a thermostatic control valve to help control emissions. It basically uses a vacuum-powered switch when the engine is cold to take warm air in from near the exhaust ... but it switches back to only cold air once the engine is warmed up.

Well, at the time I was unaware of the thermostatic control valve, so I decided to get a small piece of cardboard to cover the cold intake portion.

Does anyone know if there's a way I can get this valve to stick so it only takes in warm air? This way I won't have to even purchase anything to have a WAI/HAI.

With the cold air intake blocked, I've noticed a ~2mpg improvement on highway driving (21.43mpg on a 25 mile hwy trip at 55mph). It's the first time I've gotten over 20mpg with this brick-on-wheels.

The cardboard will work good as a temporary block, but it's not a complete seal either, it's just kind of there, mostly reducing airflow.

Any ideas?

I plan on more mods for better FE for my 1,000-mile round trip from school back home for thanksgiving break, so other suggestions would be nice too. I already increased tire pressure to 40psi (max tire-wall 45psi) and have modified my driving style (still learning that though), and plan to take my roof-rack off soon. Would lowering the air dam help at all, or just increase surface area and therefore reduce gas mileage? The front of the explorer is completely flat, not the rounded front end that started in 1995.

Thanks in advance!

Oh... also, would changing my fuel injectors to new (re-manufactured) fuel injectors improve my gas mileage? It would be changing from the stock 1-2 spray injector to a 4 spray injector. Someone on another forum site was saying how since it has 4 spray-streams of gasoline, it atomizes (??) the fuel better, and allows for a more complete burn, increasing gas mileage and HP.

I had that beast of a 4.0 in a 1997 Ranger, it did not make the power one might expect from it. I bet it got awful fuel economy but I didn't care at the time. Good job getting 20mpg!

I think people have successfully done the mod you're considering with the existing WAI.

The air dam would have to be an experiment. It certainly could help, but it could go the other way too.

The injectors sound like an interesting idea, I wasn't familiar with the issue of how many sprays it splits into. My gut feeling is that if they do help at all, it would never be enough to pay for itself.

Yea, it definitely doesn't have much power. Supposedly it has a lot of low-end torque *shrugs*. Story time: I was "hauling" a "home gym" from two hours away (t'was free). I was driving and there was this fairly large hill. I ended up flooring the Explorer, and I was still losing speed. I couldn't believe it.

On the other hand, my Buick (3.3L V6, 160hp -- same hp as the explorer) can "haul" that much weight inside of it and still easily make it up the hills, and I still get 30+mpg. I drove it to and thru colorado this past summer, car packed full of camping gear and food. Didn't have any issues power-wise, the transmission didn't like it though.

I've looked around on the 'net, and haven't found much, if anything, about warm air intakes on explorers/rangers in my year range ('91-'94). There's stuff about the thermostatic air controller, but couldn't find anything about modding it other than replacing the stock box with a cold air intake w/ aftermarket filter.

My '88 Escort has the same set up you are talking about on the intake air system. All I did was drill a hole through the snorkel on the air filter housing and ran bolt thought it with a nut on the bottom to hold the flap where it would always get hot air from the exhaust manifold.

Any chance you could post a photo of this?

Did you notice any improvement in mileage?

I read somewhere that Ford did this intake thing not only to reduce emissions (i guess just before the engine is warm), and also to keep the engine cool once at operating temperature. Would it be a bad thing to completely block off the cold intake portion of it?

I have a WAI on my car, haven't noticed any ill-effects ... but it also doesn't have the same strange (to me) intake system as the Fords.

Thanks again for your responses ... and thanks in advance for any more I may have! :)

When heavily loaded, or when towing you should not be using OverDrive in that car. My mom used to have a Century wagon similar to your car. You should select "D" instead of "(D)". Checking your owner's manual should confirm this.

Yea, now that you say it... I remember seeing something like that in the U.M.
I ended up having to shift down to 2nd to go up the hills (at ~30-40mph ... not above the recommended speed in the U.M.). It was just the shift from 2nd to 3rd that the car didn't like. Never had a problem with it shifting into 4th (overdrive) when heavily loaded ... which has been the majority of it's life the last ~20k miles if not more (college student, traveling 1,000 miles round-trip to get home ... with passengers and trunk packed full for breaks/ visits home).

They are really good cars. Mom's was a 97 Century wagon. Really nice, smooth car that drove really well. We sold it 5 years old with 160,000 miles and no problems. Still looked pretty good too. I often think that we should have kept it as a fun little car to drive to the flea market, but I already had 3 cars at the time.

-Jay

I did notice about a 10% increase in FE when I blocked the flap where if got hot air all the time, but I've lost it recently since I changed the timing belt on it. For some reason when I changed the timing belt my engine vacuum dropped several inches of vacuum, but it is gradually getting better as the belt stretches out some. Aparently the belt had to stretch some before everything got back where it was supposed to be (or where it had to be due to wear on the engine/valve train). The only disadvantages to blocking the flap closed that I have noticed is in real hot weather the engine will heat up quicker in city/stop and go traffic and the power is down a little bit and loss of power on a car that only has 88 horses is very noticeable, its like one of the horses died.

If it's a vacuum-operated flap, just find out whether applying or removing vacuum puts it in the position you want. If applying does it, run a hose to the actuator from a vacuum source on the engine someplace. If removing does it, just disconnect the actuator. Remember to plug or cap any unused vacuum connections to the engine so you don't create a vacuum leak situation.

With any luck, the actuator will flip to hot air when vacuum is applied. If you then connect it to manifold vacuum, it should flip back to cold when there is little to no vacuum... aka wide open throttle. That way you get cold air for maximum power when you need it, and warm air all other times.

I had a 93 Ford Explorer 4.0 V6 and after I took off the big wheels my father loves to put on his SUV's I got 26 mpg out of it. Look on the door for the correct size, I had to order it from General tire, they were cheap, narrow and got great MPG.

I didn't know about Gassavers back then in 06, so I just drove it without any idea how to drive for economy.

One thing that my mechanic recommended I do was to only engage overdrive above 50, if you have noticed, Ford put a giant overdrive gear in the trans, I think 70 was like 1600 RPM. So city cruising is easy, without having to bog and stomp with the trans always being in overdrive in the city.

Maybe it's just mine, but my RPM's are always above 2k when I go above ~65.
So, I usually only drive it under 55-60mph, and the tach stays around 1.5k

88 horses? Is that a term I don't understand?
I know the explorer has ~160hp

I think ford man was referring to his escorts.

you do lose power but if you don't really need that much power then it doesn't matter. my car is rated 120hp and it is well above what I need driving back and forth to work with just me in the vehicle.

my IAT temp runs 140ish right now. during the summer, it will see close to 180 degrees. during the winter will still see over 100.

...

160hp from a 4 liter engine? Torque shmork, that's pitiful! I'm sorry, but Honda was getting that from a production line 1.6 liter i4 back in 1990.

My 1987 Cadillac had a 4.1l V8 that only had 120hp. It had gobs of torque and the car was plenty fast. It was basically like a diesel engine.

New emissions regulations and the new computer-controlled TBI that they put on it resulted in a low 4000 maximum RPM. It accelerated well but top speed was limited because it didn't have enough gears to use all that torque.

Before and after that particular era, Ford and GM were getting more HP per liter, but right at that time the numbers didn't look so great. That was also a time when they really fell behind with quality. Luckily they cleaned up their act during the early to mid 1990s.

Unfortunately, the 4.1 was a trouble-prone engine. After I was in my first accident in my Regal, I had considered getting another car and replacing it. The insurance company did give me a lot of cash. I looked at my local Cadillac dealer, and they had a 1984 Fleetwood Brogham with EVERYTHING on it. Even the factory installed CB radio. Local trade, ran well, only had 90k miles on it. Unfortunately it had a 4.1 in it. If it had a 305 or a 350 I probably would have bought it.

The main problem with the 4.1 was that the head gaskets were made of some sort of special material that required an additive (only available at Cadillac dealers) to be added to the cooling system when the coolant was replaced. Backyard mechanics rarely read the manual to know this. Pretty much, the only way the cooling system was properly maintained is if the car was serviced at the dealer. The second problem was that they were putting the 4.1 in the Fleetwood. Too little engine for a vehicle weighing in at over 2 tons. because of these 2 factors, the 4.1's often had to be rebuilt or replaced between 100,000 and 120,000 miles.

My 4.1 may have had the head gasket problem. I think it ended up lasting past 200,000 miles anyway. It did have some overheating. Its biggest problems were electronic gremlins that I would probably fix quite easily now, but when I was 17 I had neither the patience nor the ability.