Acceleration/ power problem new transmission
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Acceleration/ power problem new transmission
So I was given a 1999 f150 4.6. The transmission was supposedly either new or rebuilt. (I'm going with rebuilt) Driving it for the first time today, I noticed it had very little poor acceleration. When I would get on the gas (to the floor) the rpms would shoot up (3-3.5) but the truck didn't accelerate accordingly. It feels like the power it's getting to the wheels. Driving at highway speed trying to maintain a speed at over 70 the truck wanted to stay at 2500 rpms but if I let off the gas just a touch it would shift up (into overdrive I think) and level out at just below 2000 rpms, but if I accelerated even just barely, it would down shift and go back to 2500. I've also noticed the truck runs 5 mph faster than it reads with stock sized tires. I've check the tans fluid and it is bright red in color and at the appropriate level. I crawled under the truck and noticed the trasfer case mount was wet with fluid (not dripping) and the rear output shaft of the transfer case was also wet. Could this be a transfer case problem?
Last edited by Josh726; Dec 4, 2015 at 03:00 PM. Reason: New information
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Normally transfer case would not cause poor acceleration.
However fluid dampness suggest the rear seal may be leaking or the seal between the transmission and the transfer case is letting fluid leak by and causing an overfill leakage.
This still would not normally cause poor acceleration.
Otherwise you don't know what all was done to the overall transmission.
.
The difficulty in keeping it in OD at normal level road speed suggest a drag or some other loading issue.
The trans drops out of OD due to the 'advanced throttle' and 'low rpm' logic telling the computer to down shift to satisfy your driving requirement at that moment..
Could even be plugged Cats or muffler/tail pipe restriction.
You will have to check out these possibilities with an unknown truck.
Good luck.
However fluid dampness suggest the rear seal may be leaking or the seal between the transmission and the transfer case is letting fluid leak by and causing an overfill leakage.
This still would not normally cause poor acceleration.
Otherwise you don't know what all was done to the overall transmission.
.
The difficulty in keeping it in OD at normal level road speed suggest a drag or some other loading issue.
The trans drops out of OD due to the 'advanced throttle' and 'low rpm' logic telling the computer to down shift to satisfy your driving requirement at that moment..
Could even be plugged Cats or muffler/tail pipe restriction.
You will have to check out these possibilities with an unknown truck.
Good luck.
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This is what the leak looks like. The service engine like it on, but I don't know the associate codes. As far as the OD goes at highway speeds when it wants to run @2500 rpms I can turn the overdrive off and it'll just up to 3000 or more.
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That is the belt making noise.
You must remember that you have everything running at 4k then all of a sudden asking it all to slow down to the next upshift RPM that is lower.
Everything suddenly has to slow but can't due to inertia of the driven parts.
The belt is ready to be replaced.
Good luck.
You must remember that you have everything running at 4k then all of a sudden asking it all to slow down to the next upshift RPM that is lower.
Everything suddenly has to slow but can't due to inertia of the driven parts.
The belt is ready to be replaced.
Good luck.
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I would look at the front and rear Ox sensor action on both banks with a Scanner to see what they are doing.
If one side is not switching properly, then a back pressure test could be done.
It a bit if a hassle but considering the cost of a Cat assembly it's worth it.
In front of the first cat set up a connection pipe to attach a Vacuum gage that will read both vacuum and pounds of positive pressure.
This will require a small hole in the pipe
It has to be a low pressure gage because your trying to read several pounds back pressure if the cats are restricted.
Start the engine and run it up to several thousand RPM and while looking at the pressure developed.
If it in more than 2 to 3 psi suspect the cat of being restricted.
.
To review, you need to look for signs of a fault with a Scanner first.
Then act on those results.
Good luck.
If one side is not switching properly, then a back pressure test could be done.
It a bit if a hassle but considering the cost of a Cat assembly it's worth it.
In front of the first cat set up a connection pipe to attach a Vacuum gage that will read both vacuum and pounds of positive pressure.
This will require a small hole in the pipe
It has to be a low pressure gage because your trying to read several pounds back pressure if the cats are restricted.
Start the engine and run it up to several thousand RPM and while looking at the pressure developed.
If it in more than 2 to 3 psi suspect the cat of being restricted.
.
To review, you need to look for signs of a fault with a Scanner first.
Then act on those results.
Good luck.
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Posts: 7,907
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You have 4 different groups of failures in the code list.
The 161 is an open heater circuit to the bank 2 rear Ox sensor. Driver side.
Look at the connector and harness wiring in the area of the sensor.
.
Code 401 is a low flow test failure of the EGR system.
Could be the path into the intake behind the EGR valve is plugged with carbon or even the DPFE sensor is not able to report the test result.
.
171/174 is an air leak into the intake system. The excess air has shifted the Long Term Fuel Tables for both banks. Check the PCV hose going to the rear of the intake for a rubber fitting failure and/or some other intake leak..
.
Code 442 is failure code for one of the EVAP system test. It detected a small leak as opposed to a large leak.
It could be the tank cap, the fill hose or even a leaking solenoid valve.
.
There are your 4 test fail areas.
Clear them one at a time beginning with the 171/174 code fault, then go to the 401 failure, then take your pick between the last 2.
Good luck.
The 161 is an open heater circuit to the bank 2 rear Ox sensor. Driver side.
Look at the connector and harness wiring in the area of the sensor.
.
Code 401 is a low flow test failure of the EGR system.
Could be the path into the intake behind the EGR valve is plugged with carbon or even the DPFE sensor is not able to report the test result.
.
171/174 is an air leak into the intake system. The excess air has shifted the Long Term Fuel Tables for both banks. Check the PCV hose going to the rear of the intake for a rubber fitting failure and/or some other intake leak..
.
Code 442 is failure code for one of the EVAP system test. It detected a small leak as opposed to a large leak.
It could be the tank cap, the fill hose or even a leaking solenoid valve.
.
There are your 4 test fail areas.
Clear them one at a time beginning with the 171/174 code fault, then go to the 401 failure, then take your pick between the last 2.
Good luck.
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This line is leaking. It's hard to tell from the picture but it's cracked on the far left. Not sure what this line is called following to the right it goes into the PCV valve following it to the left it goes back behind the battery box
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