Milage Sucks

[cpw266]

My 98 Explorer V6 has been getting bad gas milage lately. About 13 MPG. A guy at work pointed out that his ODB reader indicated the coolant was too cool 160 degrees max even after the car ran quite a while. I noticed that the guage was lower than normal but can this affect milage?

Second question: On the driver side front I have noticed a thumping noise when moving. I can feel it in the pedals but it seems like its closer to the where the axle goes into the transfer case. It seems to be getting mor pronounced as time goes on. I have 104K miles on this vehicle. I noticed a small thumping when I bought it at 30 K. Now it's getting worse. Is there abearing or something that is known to go bad?


Third question: On decelleration and braking the car will sometimes downshift quite hard most pronounced at around 35 MPH. I had it to a tranny shop and they say they find nothing wrong. They say there is some minor play in the rear end but nothing to be concerned about. ANy Ideas?

 

[rtbrjason]

I'm new with explorers but have seen coolant temp issues on previous vehicles cause dips in mpg. Typically the reason would be that the pcm sees a cooler than normal coolant temperature and continues to run somewhat rich to warm the engine up. This is normal behavior for the first few mins of a cold start. In the past this issue has usually been relative to a funky reading from the coolant temp sensor. In one of my previous cars, the sensor was a plastic resign tipped design and was actually cracked. Not sure if we have similar problems with any of the Explorer engines though.

 

[aldive]

Check your thermostat.

Good luck .....

 

[ExplorerDMB]

Thermostat is a good place to start.

-Drew

 

[gijoecam]

1) Indeed, if you're running cool, it can wreak havoc on your fuel mileage. Typically when the t-stat sticks open, it fails to come up to temperature or takes a VERY long time to warm up. I would be surprised if that was your problem, but for a $13 part, I'd say that it probably couldn't hurt.

2) The axle doesn;t go into the transfer case. The front wheel goes into the front axle, and the front driveshaft runs from the front axle/differential to the transfer case. I'm unclear on where you're saying your thumping noise is coming from. If it's the wheel area, a bad front hub/bearing assembly or a bad CV joint could be the culprit.

3) A sudden or jarring downshift at 35 could certainly be a trans issue. It may be a torque converter failing to unlock at the proper time, or something else, but a GOOD trans shop with experience working on that trans should be able to troubleshoot it in short order. You may want to ask over in the driveline forum for more info on this one.

Good luck!

-Joe

 

[jah81592]

if you engine doesn't heat up to the manufacturers operating temp then you will stay in open loop mode and that would be your reason for such low gas mileage. The Ford computer is designed to go into closed loop at around 185+ degrees.

 

[new2tn]

try using some Lucas trans fix that stuff works great, I also used another additive but, can not remember the name. I will post it tomorrow.

 

[J. Kennedy]

Which one is the coolant temp sensor? I bought one, and it has 2 wires & is on the driver side of the Tstat. On the passenger side of the Tstat is a one-wire sensor. What is this? Will it affect my mileage?? Thx

 

[cpw266]

Thanks

It was the thermostat. Thanks everyone! It runs great now.

 

[gijoecam]

I'm guessing that the new t'stat probably solved the #3 shifting issue too, right?

-Joe

 

[gavin]

the thumping noise.. as was stated, possibly wheel bearing or cv joint, or possibly the cv joint on the driveshaft; those are known to go bad, and I've been through a couple front shafts myself.