94 f150 300 4.9 terrible gas mileage.

[88ranger5speed]

I have a 94 f-150 straight 6, 5 speed, 3 inch body lift running 31x10.50x15 as my dd. one day a spark plug ejected from the engine and it ran fine after we put a new one in it. But now the check engine light comes on when running under about 2k rpms. It's getting 10mpg anything I can do to help it a little? Already put a new o2 sensor in it and ran a few cans of seafoam through the gas tank.

But she is beautiful.


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[88ranger5speed]

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[adsm08]

I thought 10 MPG was good for those engines.

 

[88ranger5speed]

Step dad claims it was getting 18 before he passed the torch.


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[88ranger5speed]

14-18 is about average.


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[RonD]

What is the Code from the CEL?

Engine needs to get up to operating temp for best MPG, running cool is not good, should be running about 200degF when warmed up, on most Ford gauges that is just below 1/2

Fuel pressure test would tell you if there are any leaks, you don't always smell gas leaks if it is leaking into the engine.

Watch for neighbor with siphon hose, lol, that lowers MPG, PDQ

 

[AgPete139]

How many times does the light flash with the key in the ignition? What's the error code with the OBDI?

Could the truck be running on the lean side? Does it sound like it's gasping for air or fuel when you get on the throttle? Is it starving for fuel under 2k RPM's? This could be a fuel issue, and possibly why you threw a plug.

Just asking to make sure, but have you changed the fuel filter? I've seen some cars that have never had them changed, and they suffer from poor gas mileage, tired fuel pumps/senders, and once a bad idle. It makes a difference, especially when you can't blow through the filter.

 

[88ranger5speed]

Just got a code reader for my iPhone. Will test it out tonight. Runs great though. Goes right with it. I think it's something to do with the check engine light. It stays on when I turn the key. Temperature gauge stats around 1/4 of the gauge.


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[adsm08]

You got an OBDI reader for your Iphone? Do they have an android version?

 

[88ranger5speed]

Yeah it plugs in and reads it wirelessly. Idk. My uncle gave me this cuz he got an android so I'm assuming no.


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[RonD]

I know there are OBD II bluetooth readers, never seen a OBD I reader with bluetooth/smartphone interface.

1/4 on temp gauge could be normal but I would just do a simple test to see if t-stat is stuck open.
Start cold engine, pop the hood and feel the upper rad hose.
Let engine idle for 2 or 3 minutes and feel the upper hose again, it should still be cold.
If hose is warming up with the engine then it is time to replace t-stat.
Use 192-195degF t-stat

160 or 180degF t-stats will lower MPG and cause dirtier oil, so less lubrication.
That's from SAE testing, operating temps between 200-230degF provides better burn off of water and fuel contaminants in the oil.
So contrary to popular myth "running cooler" is NOT better for the engine, lol

 

[88ranger5speed]

I got a 10$ app off of the App Store and it is awesome. It runs real time diagnostics on your engine while it's running. Gas mileage, horse power, all kinds of things.


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[RonD]

Yes, but those are for OBD II(2) equipped computers(EECs), and you also need the bluetooth part installed on the OBD II port.

The 1994 will have an EEC-IV computer so OBD I(1)
Good read here on how to get the OBD I(1) codes:
http://www.therangerstation.com/tech_library/OBD_I.shtml

 

[88ranger5speed]

I realized that. I was using it in our 02 powerstroke and 04 gmc envoy. It gives you gas mileage, 0-60 times. 1/4 mile times.


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[ridgerunner]

I love the older Fords, got a 90' 5 speed 300 6 as well with 3.55 gears. When it was my DD it got between 13 and 15mpg steady. I once got 16.4 on a trip and I had a good tail wind, going down hill the whole way, and I had just eaten a whole lot of Mexican food so I'm sure that helped . But 18mpg is pure BS IMO. I also had a spark plug or two pop out from time to time.