The Ranger Da Vinci Code

[Logand681]

I have a 1988 Ford Ranger XLT v6 2.9 Manual 5-speed RWD. Im getting terrible terrible gas mileage(8-10mpg). The truck runs like a top, idles perfect and has good pick up although it could be better. Ive replaced the clutch, clutch saftey switch, clutch master cylinder, flywheel. starter, cap, rotor, wires, plugs, in line fuel pump, in tank fuel pump, fuel filter, breather valve(in gas tank), carbon canister, fuel pressure regulator, fuel injectors, air filter,coolant temperature sender and sensor, ECU, 02 sensor, back half of exhaust include muffler, MAP sensor, throttle position sensor. Probably forgetting a few things but ive replaced all of those in past 6 months and all have been brand new parts with lifetime warranties. Don't know what else it could be. Can anyone help?

 

[ab_slack]

Numbers seem very low.

Stock tire size? In your computation are you using gallons consumed between fill-ups. Just asking because sometimes people try using fuel gauge and that is so inaccurate as to provide meaningless numbers.

Also consider. Fuel leaks. Someone siphoning fuel from tank.

 

[Logand681]

I thought it might be getting syphoned out so I bought a gas cap with a lock. I fill up 10 gallons and I'll go 100 or so. A little more if I get on highway. When I'm empty or so the gauge says and I fill back up I can out ten gallons in Samhain so the gauge works accurately. I check for leaks with the I did the pumps and filter as well.

 

[Logand681]

I have 15s on it stock is 14s

 

[JoshT]

Wheel size doesn't matter as much as tire size.

 

[Logand681]

I don't have anything crazy as far as tires nothing to wide or anything. I think there 225/75/55r

 

[Andy D]

Thats tall enough to screw up the odometer and the speedo.

 

[Logand681]

It's not the tires. I was having the gas problem before I put the 15s on. Had 14s on it previously. And it defiantly wouldn't drop my gas mileage over half. Guy I go to school with has a 87 2.9 v6 lifted and has 35's and them and he gets 18mpg

 

[Slammin Sam]

Now that you've hung all those new parts on it, it's time to take it to someone that can hook it up to diagnostic equipment and find out what's really happening. There is always a chance one of those new parts is defective.

 

[Logand681]

We had it hooked up to a snap on machine at school. The only code it would pull is a lean exhaust code which doesn't make sense with how much gas it's using. I already had a new 02 sensor and injectors and all parts hook up. So I figured it was a faulty 02 sensor so I went and got it warrantied out and nothing changed. I'm down to replacing the distributor and distributor control module as we speak. I'm hoping that it's been a firing issue.

 

[adsm08]

OK, forget what you THINK you know about what the codes mean.

Lean code means that the oxygen sensor is still seeing free oxygen in the exhaust stream and the computer has adjusted the fuel mix past a certain preset point but has been unable to correct the condition.

This can be caused by a leak in the intake gaskets, allowing air that the computer can't see to get in. It can also be caused by an exhaust leak upstream of the sensor, or there could be faulty wiring effecting the signals used to calculate the A/F mix.

If you have access to a Snap-On scanner hopefully you have access to a smoke machine. Smoke the intake and look for leaks.

 

[AllanD]

What Temp T-stat do you have in it?

Because if some joker sold you a 180deg and you have even a slightly mis-calibrated Engine Coolant Temp sensor (no, not the gauge sensor) the engine management will behave normally but keep the engine in "open loop" as though it were cold all the time.

I've also seen a "Wonky" ACT (Air Charge Temp) sensor (screwed into the side of one of the intake runners on the upper intake) cause mileage issues.