4.0 OHV Auto, Running cold? Poor Gas Mileage. - Ranger-Forums - The Ultimate Ford Ranger Resource


4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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  #1  
Old 10-11-2008
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4.0 OHV Auto, Running cold? Poor Gas Mileage.

Hey guys, I just wanted to follow up with other fellow 4.0 OHV owners.

I have a 98 4x4 ranger that has been giving me the worst gas mileage! as low as 13ish typically 14-15, its has no lift and 31" tires. I have done the port and polish on the MAF housing which seemed to free things up a bit but I am concerned because it doesnt ever seem like my truck gets warm!

I have a photo but the forum does not seem to want to let me attach it. Basically the temp gauge hangs around the beginning line above C (the start of the long curved bar). If i drive it hard and the weather gets above 70 degrees then it floats up a little more but as soon as I ease off the engine its back down.

Is this normal for these engines? Could it be the cause of my crappy gas mileage?

The Truck only has 43,000 original miles!! I beleive it has the original plugs and wires, i put a new air filter in and thats about it!

The other odd thing that i noticed happening is after traveling down a long steep gravel road the engine started to sputter and felt like it had no power at all like it was having a hard time getting gas, after traveling back on straight road for a little bit it came back to life like nothing happened and ever since its been fine. If anyone has an idea about that feel free to let me know.. fuel filter?

One more thing i wanted to check up on, when in nuetral do you guys normaly idle around 1100rpm? It just seemed awfully high, maybe the gauge is off but I am so used to seeing the 700-800 range in my previous vehichles.

Thanks!!
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Old 10-12-2008
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idle seems fine to me but theirs a bolt you can loosen or tighten to increase or decrease your idle rpms
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  #3  
Old 10-12-2008
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Change the t-stat.
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  #4  
Old 10-12-2008
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I found some directions here but it did not mention a new gasket? is one needed? do you guys normally use some waterpump silicon also?? I just dont want that badboy to leak when I am up in the mountain. Also torque specs on the bolts?

I guess you guys usually see your temp gauge hold steady around half?? Mines probably screwed up.

Second, for a 98 with 43K would you guys reccomend a tune up? If so what are the best plugs/wires for these rigs for best economy and power? I was looking at some autolight plats and the BWD nascar wires. I should probably pick up a fuel filter too.

Thanks in advance!

BTW- Cold Napalm where is this idle adjust screw you mentioned? I would like to get my rig to idle at about 700-800rpms. Anyone know of a problem or side effect doing this? And has anyone had any first hand experience doing the MAF housing port and polish modification? any adverse side effects?

Update: drove about 40 miles today and looks like i was averaging about 11-12mpg's Freeway!!....

------------------------------------------------------------------------

follow your upper radiator hose to the engine block. There is 3 bolts that holds the thermostat housing on the block (10mm i believe).

Since you have to drain some of the antifreeze to replace the thermostat, might as well do a complete flush of the cooling system while you are at it.

Tools Needed:
- 3/8" drive ratchet
- 3/8" 10mm socket (don't me to it, but I believe it is this size)
- 3" 3/8" extention
- 3/8" swival socket (not necessary, but makes it easier)
- 5 gallon bucket (to drain anti-freeze)

Parts Needed:
- new thermostat
- 2 gallon anti-freeze (3-4 if you are doing a complete flush and fill)


Steps to Replace:
1. Drain the anti-freeze out of the radiator (this will keep anti-freeze from pouring out the thermostat when you remove it)
2. Remove the intake from the throttle body and lay it out of the way.
3. Take the tention off the drive belt so you can get to all the bolts.
4. Remove those 3 bolts and pop the seal on the housing (no need to remove the hose from the housing).
5. Pop the thermostat out of the block, put a new one in the same way.
6. Re-install the housing and the 3 bolts; do NOT over tighten the housing bolts.
7. Install the drive belt back on the pullies.
8. Fill the radiator up with anti-freeze. If you are doing a complete flush, now is the time to do the flush.
9. Install the intake tube back on the throttle body making sure that all the plugs and vacuum hoses are still attached to the intake tube.
10. Start the truck. Let it warm up to temperature. When it comes up to temperature, shut the truck off let it cool down.
11. Remove the radiator cap and top off the radiator
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  #5  
Old 10-12-2008
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If someone could also point me in the right direction for the fuel filter that would be great!
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  #6  
Old 10-12-2008
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Quote:
Originally Posted by ColdNapalm View Post
idle seems fine to me but theirs a bolt you can loosen or tighten to increase or decrease your idle rpms
Where isthis bolt located?

I average 14.5mpg right now and less in the winter because of the gas and such. I would guess it to be a thermostat.
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  #7  
Old 10-12-2008
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So many questions..

I have another one. I had a flowsound muffler put on a few months ago and its already starting to rust. I would like to get some high temp paint for it, any ideas for eliminating the rust too? Rustoleum is great but i dont think they have a high temp version.. I will of course wire brush it the best i can but its a tight space.

I was hoping to do all this work tommorow morning, t-stat, plugs, fuel filter, idle adjust. If you guys could let me know how your experiences with those items are that would be great. What plug type? do i need gaskets, silicon, stuff like that for the t-stat. torque specs ect.
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  #8  
Old 10-12-2008
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There is an O-ring type gasket that should come with the new t-stat. Make sure you take note of the way the old t-stat is installed so you don't make the mistake of installing the new one backwards.

I've also used a little RTV on the T-stat housing flange and never had a leak.

Autolite platinum plugs will work fine. Motorcraft platinums are the best for your Ford.

Most "premium" wire sets from the part stores are made by the same manufacturer and are good quality.

I wouldn't adjust any idle screws, that's not an appropriate repair.

You ahould also consider cleaning the MAF sensor.

A new fuel filter is a great idea. You will probably need the "special tool" in order to relase the fuel line connections from the old filter. See:
Quote:
The real key to removing the special fittings from the fuel filter is the technique employed using the special fitting removal tool. Once the fuel pressure has been relieved and the filter mounting bracket and band clamp have been loosened and moved out of the way, proceed as follows:

Remove the lock clips that are placed over the fuel filter tubing and the fittings. They should come off without having to use excessive force. A small screwdriver inserted into the open end of the clip at the fitting end can serve as extra leverage if needed to get the clip off.
Grasp the fuel filter in one hand and one of the fittings in the other. Try gently moving the fitting back and forth while it is still in place. Notice that there is about 1/8" to 3/16" worth of movement. Pull gently until the fitting is all the way back as far as it will move. Clip the special fitting removal tool (the tool should be designed to work with 3/8" fuel lines) over the fuel filter tubing. Now push the fuel line fitting towards the tool as far as it will go. While still holding the fitting in, use your pointer and index fingers on the same hand holding the fitting to pull the fitting removal tool "into" the fitting itself as far as it will go (the tool should "bottom"). Still grasping the fitting and tool together, pull them back in the direction for removal, keeping the tool inserted in the fitting (important). At some point, the tool will stop as it hits the fitting retainer "nub" on the filter tubing. Keep the tool pressed against the retainer nub (use ! ! your other hand now for this) and continue pulling the fitting off of the tubing. It should come off with only a few pounds of force. Repeat the procedure for the other fitting.

It is important to push the fitting in towards the filter to engage the fitting removal tool as this relieves the tension on the "fingers" prior to insertion of the tool. If you don't push the fitting all the way towards the filter first, the tool will not release the retainer spring and you won't be able to pull the fittings off. This is the mistake that I made repeatedly the first time I tried changing the filter in my vehicle. Don't use the tool to try and "pull" the fitting off with - it isn't supposed to work that way.

The fuel filter holds a fair amount of gasoline so have a small cup and a rag ready to catch or soak up any spillage (there will be some). If any gasoline gets onto the frame rail, it will remove the protective coating and paint, so be sure to wipe it off immediately (I didn't and now have a couple of bare spots on the frame to show for it!)

The new filter simply installs by pushing the fuel line fittings onto the filter until the fitting locks (you'll hear it click). Be sure that the filter is installed with the flow arrow pointing in the proper direction (towards the front of the vehicle). Reinstall the lock clips over each fitting and the band clamp and filter bracket.

Contributed by Mark McLauchlin
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  #9  
Old 10-12-2008
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Thanks Joe,

I will scratch the idle adjust.. As for the MAF i just cleaned it about two weeks ago when i ported and polished the MAF housing. (whether or not this was a good idea to begin with i dont know...) If someone has some readouts or specs for the stock housing setup and the modded housing please let me know! After i did it i thought by making the MAF flow more freeling i would make it run a little richer? (More air is passing by the MAF now since the "rerouted" port is gone?)

As for the plugs should i go with the single plats, double plats, or the thin wire plats? Lot of people say just go with the double, some say the thin wire. I have not heard anyone comment on the single plats.

To be honest i was not even going to worry about the plugs and wires, i mean 43,000 miles??.. But then again the truck is now 10 years old. At the very least i figured the wires are probably perfect? Maybe the plugs could use a freshen up.

Right now i am more worried about getting the truck to run at temp and painting the muffler...

As far as the fuel filter is concerned i am definitely going to try and relieve the pressure first, when i changed my mustangs filter i about died when all that gas when spraying everywhere...
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  #10  
Old 10-12-2008
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t-stat
i had the same problem in my 99
runnign cold
****ty gas mileage
changed t-stat
like new
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  #11  
Old 10-12-2008
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10 years old, it's due for a tuneup regardless of mileage. Gasoline is expensive these days.

Go with the double plats or the fine-wire plugs, which will last longer then the single plats.

I'm not a fan of MAF mods, so I can't help you there. I've read a lot of stories on the Taurus boards about guys modding their MAFs and then regretting it.
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  #12  
Old 10-12-2008
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I as well with the MAF mod however it seems many people with the 4.0 OHV have had great success. If you have the 3.0L engine i would be extremely cautious, many owners reported problems. I figured since ford used the same MAF housing for the 3L and 4L engine i might as well try something new.
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Old 10-12-2008
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When your temps are below 160F the PCM will command a high idle and a richer A/F mixture.

I think your poor milage and high idle could be as simple as flushing the coolant and replacing the stat.

As far as a plugs and wires. I'd wait and see what the new stat does first.

Rich
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  #14  
Old 10-12-2008
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Thanks Rich, I will pick up a prestone flush kit and some flush fluid, try that and report back tommorow.

I also saw from another forum you have experience with computer programming for these rigs? or maybe only the newer ones?
I was curious if any MPG gains can be had by that method? Also to be honest i always thought since i bought this truck the auto tranny shifts kind of funny.. Its not a huge deal to me but i would think a reprogram could help out a lot. I know absolutley nothing about this topic. is it as simple as buying a programmer and plugging it into the truck?

Another question i had about these trucks is the engine or transmission mount. My buddy had the same year rig as mine except the 3L engine and when he accelerates it always felt like either the engine or tranny was moving (a small bump feeling) its hard to explain but is this common? I noticed mine also does this when you take off from a stop. It feels like mounts but they look fine.

Thanks!
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  #15  
Old 10-13-2008
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Quote:
Originally Posted by koocuz View Post

Another question i had about these trucks is the engine or transmission mount. My buddy had the same year rig as mine except the 3L engine and when he accelerates it always felt like either the engine or tranny was moving (a small bump feeling) its hard to explain but is this common? I noticed mine also does this when you take off from a stop. It feels like mounts but they look fine.
That sounds an awful lot like the infamous "driveline clunk" that some '98+ Rangers are prone to. The remedy is to clean and re-lubricate the driveshaft slip yoke assembly. Check out: 1998+ Ranger Supercab Sip Yoke Lubrication
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  #16  
Old 10-13-2008
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Quote:
Originally Posted by koocuz View Post
Thanks Rich, I will pick up a prestone flush kit and some flush fluid, try that and report back tommorow.
Don't forget the stat. That's most important. And come to think about it.. if it's that old the rad cap **might** ought to be changed too. If it's cheap.. might as well.



Quote:
Originally Posted by koocuz View Post
I also saw from another forum you have experience with computer programming for these rigs? or maybe only the newer ones?
I was curious if any MPG gains can be had by that method? Also to be honest i always thought since i bought this truck the auto tranny shifts kind of funny..
Its not easy or cheap to do. In my experience the "tuners" out there take generic stabs in the dark at changing shift pressures and shift timing.

I've gone way beyond what I've seen from ford, bama, or henson.
Bama and henson *only* upped the pressures as best I can tell. Well.. that resulted in low throttle low speed harsh shifts. IMO that's just being lazy on thier part.

What I've done is conduct MUCH trial and error in shift pressures and timing of both shifts and TQ convertor lockup characterists. At low throttle/speed mine shifts just a hair firmer than stock. You'd not notice it unless I'd told you. Then as throttle postion/rpms/speeds increase my shifts increase in pressure and quickness. I've really fine tuned the 0-25% areas most. After all in daily driving thats where you operate for the most part. Above that I've not spend as much time tweaking and my shift points mimik fords stock programming. (except firmness and quickness)

If you can have a tuning company out there address these things then you could wind up with the same or similar tranny functions that I've developed. Good luck.. because I doubt they have taken the time that I have.

As far as MPG improvements. There are some very very small things you can do to make it better. But so far *on avg* my milage is only about 1mpg better than the tunes I received from bama or hensen. I've increased EGR opening, leaned it out a bit, and what gave me the biggest improvement was to lower the 5th gear shift to about 34mph (tq convertor quickly follows too) But... going into 5th that low really only helps in the 35 to 42mph area. Above that speed and it's no different.

What I've done is *not* cost effective. Rather I've done this as a learning tool / excersize.

Rich

Last edited by wydopnthrtl; 10-13-2008 at 09:08 AM.
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  #17  
Old 10-13-2008
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Yea i will definitely pick up a new thermostat this morning. Joe, thanks for that PDF its very detailed. Do you know if this is just an annoyance or something that should be fixed? I just wanted to be sure it was nothing serious but to be honest thats a bit of work for a small thump on accel..
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  #18  
Old 10-13-2008
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Quote:
Originally Posted by koocuz View Post
Joe, thanks for that PDF its very detailed. Do you know if this is just an annoyance or something that should be fixed? I just wanted to be sure it was nothing serious but to be honest thats a bit of work for a small thump on accel..
Personally, I don't like the idea of anything clunking around in my driveline, in my experience that's never a good thing. In my Ranger's case, I get a very pronounced "thunk" which definitely takes away from my driving experience, and it progressively gets worse until it becomes an outright annoyance. I've re-lubed my Ranger's slip yoke 3-4 times already and so I've got the process down to about 90 minutes. It's not a difficult project at all, although like most things the first time through might take you a little longer.

On the other hand, if you can live with the symptoms you are experiencing, then you might wait and see if it gets any worse before diving in.
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  #19  
Old 10-18-2008
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New t-stat is in with fresh coolant. The truck runs great!!

I did not do the tuneup but i did do the fuel filter, plugs and wires will be in my trucks future though.

thanks!
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  #20  
Old 10-19-2008
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the driveline clunk is freakin annoying

im due for another relube
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  #21  
Old 10-23-2008
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Whelp, i have been driving a bunch, i have gone 170miles and im at a quarter tank!! What the heck. The truck runs great but it sucking the gas like no tommorow.

any ideas?
maybe i will do the plugs and wires after all... I cant imagine the port and polish on the maf would do that...
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  #22  
Old 10-24-2008
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Whats the mileage?

When it gets cold the truck uses more fuel. Colder air = more dense = needs more fuel to maintain proper mixture.

Typically around freezing i will get about 13 -14 city. Below zero it will drop to 10 - 11. When it gets below freezing i tend let it warm up for 3 - 5 minutes.

Last tank was 16.2 city. Average temp was around 60.
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Old 10-24-2008
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IMO that's horrible mileage. I'd suggest these next.

1) Check for a dragging brake (fix if neeeded) and check for underinflated tires. Drive it for another tank and see if that "fixed" it.


2) Buy some MAF cleaner and spray it on the MAF. Don't touch those little wires.. just spray it down real good. The fluid will emulsify the debris so don't get too crazy with pressure or anything.
Then dis-connect the battery and turn on the headlights. Turn them off, reconnect, and put the motor through it's idle learning curve once fully warmed up. Drive it for another tank to see the results.

3) Change the two front 02 sensors. (have them checked if at all possible because they are expensive)


Rich
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Old 10-24-2008
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Old 10-24-2008
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When I did the port and polish on the MAF housing I cleaned out the MAF with specific MAF cleaner. I however have not cleared the computer since I did the thermostat or the MAF so I will try that next and look into O2's that might not be doing so well.
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