Automatic locking hubs
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Cross-Country
Joined: Oct 2003
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Automatic locking hubs
Hello Team,
last weekend I was cutting wood and put my 2001 F150 into four wheel drive for the first time in a long time. I did it "just in case". Anyway, now my fuel mileage really took a nosedive. Is it possible one of the hubs did not unlock? If so, how can I test? Common problem?? 215,000 and going strong!!!
Any help is appreciated,
-John
last weekend I was cutting wood and put my 2001 F150 into four wheel drive for the first time in a long time. I did it "just in case". Anyway, now my fuel mileage really took a nosedive. Is it possible one of the hubs did not unlock? If so, how can I test? Common problem?? 215,000 and going strong!!!
Any help is appreciated,
-John
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
First thing is you don't have locking hubs.
The front CV axles are splined into the front hubs.
There is nothing to move, lock or unlock at that part of the drive line.
The lockup takes place inboard near the carrier where an actuator slide locks the axle.
.
You need to verify the front is pulling or it is not.
The easy way to tell is make a sharp turn.
Does the front wheels 'hobble" and become hard to steer?
If yes 4wd is in.
If no 4wd is not in.
How does it acts in 4L?
If neither you have some other issue such as Ox sensor plug pulled off for which a CEL and code would be set or some other issue..
Good luck.
The front CV axles are splined into the front hubs.
There is nothing to move, lock or unlock at that part of the drive line.
The lockup takes place inboard near the carrier where an actuator slide locks the axle.
.
You need to verify the front is pulling or it is not.
The easy way to tell is make a sharp turn.
Does the front wheels 'hobble" and become hard to steer?
If yes 4wd is in.
If no 4wd is not in.
How does it acts in 4L?
If neither you have some other issue such as Ox sensor plug pulled off for which a CEL and code would be set or some other issue..
Good luck.
Thread Starter
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Cross-Country
Joined: Oct 2003
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I was really unsure as to the actual "engagement", so I knew it was something other than a manual activation to get it into 4x4. I just thought it was weird coincidence, as I am always watching my mielage.
Thank you for the replys,
-John
Thank you for the replys,
-John
Elder User
Joined: Apr 2012
Posts: 990
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From: Tamaroa, IL
His front end maybe locked in and the transfer case could still be in 2wd. One way to check if anything is locked in is to put the truck in 2wd and try turning the front driveshaft. In 2wd the front shaft should spin freely. If not, the transfer case is locked in, or the front end is still locked in (or both). The vacuum actuator on these trucks are prone to failure, so there is a chance that just the front end is locked in. Generally the transfer cases don't give problems.
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Cross-Country
Joined: Oct 2003
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Update;
The front driveshaft DOES spin, so I am free from any drag up front. Service Engine Soon light came on and AutoZone tells me I have P0171 & P0174 codes, which are said to be cylinders 1 & 2 running lean. I added some Lucas injection cleaner as a maintenance thing. I thought about cleaning the mass air sensor. Also, shame on me but 218,000 miles and NEVER had a tune-up. It still runs like a champ but mileage has dropped from around 17MPG to 15. Additional thoughts??
The front driveshaft DOES spin, so I am free from any drag up front. Service Engine Soon light came on and AutoZone tells me I have P0171 & P0174 codes, which are said to be cylinders 1 & 2 running lean. I added some Lucas injection cleaner as a maintenance thing. I thought about cleaning the mass air sensor. Also, shame on me but 218,000 miles and NEVER had a tune-up. It still runs like a champ but mileage has dropped from around 17MPG to 15. Additional thoughts??
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
On the code interpretations, no the codes do not tell you any specific cylinders are the cause. Leave those cylinder alone.
The codes are the result of fuel tables in the computer being shifted out of limits.
The OX sensors are detecting to much oxygen in the exhaust gas, usually due to unaccounted for air leak at some point in the intake tract.
"Pecking order"; to much unaccounted intake air >>>> makes combustion too lean>>>>>is detected by the OX sensors >>>>>>>>sensors feeds this lean signal back to the PCM in a loop function >>>>>>PCM tries to correct by shifting tables 'rich'>>>>>>these tables being out of limits sets the CEL and codes for both banks (171/174) since the issue is common to all cylinders not just one or two on one bank.
You may or may not detect any drivability change but fuel mileage suffers.
Good luck..
The codes are the result of fuel tables in the computer being shifted out of limits.
The OX sensors are detecting to much oxygen in the exhaust gas, usually due to unaccounted for air leak at some point in the intake tract.
"Pecking order"; to much unaccounted intake air >>>> makes combustion too lean>>>>>is detected by the OX sensors >>>>>>>>sensors feeds this lean signal back to the PCM in a loop function >>>>>>PCM tries to correct by shifting tables 'rich'>>>>>>these tables being out of limits sets the CEL and codes for both banks (171/174) since the issue is common to all cylinders not just one or two on one bank.
You may or may not detect any drivability change but fuel mileage suffers.
Good luck..
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Cross-Country
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So, with all that said, what direction should I take. A lot of posts on here suggest a vacuum leak. Something to investigate? If so, what is the best method?
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check all vacuum hoses... two above the drivers valve cover to the egr.. about 1/4 or 3/16 ID and 8 inches long. Look at the hose to the back on the intake manifold. Look at the PVC hoses... your looking for old/ hard/ cracked.. leaking.
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