very high engine idle, as soon as and as long as wheels turn? it is hard in parking l
 

my 98 xlt 3.0 4x4 is deciding to "jump" engine rpm as soon and as long as the wheels turn. It will not come back to idle till the wheels stop turning?? Any ideas pls?

???

Idle goes high when speedometer goes up
Idle goes high when turning the steering wheel?

high idle
 

Yes so I've learned but this is different. The computer shows 171 and 174 codes and 453 code the fuel pump and sending unit was replaced a year ago and the pressure sensor too? My manual is a bit confusing on the subject of pressure regulators most are in the pump/sending unit assemblies but it also mentions something on the fuel rail? Some days I have shifting issues with the automatic tranny, wonder if this is part of problem?

1986 thru 1997 have fuel pressure regulator(FPR) on the engine end, its connected to a Return line that sends unused fuel back to the tank
These ran 35psi pressure, pump generate 85psi, so return line was always flowing fuel back to the tank

1998 to 2000 have the FPR in the tank with the pump, but its on the fuel pump OUT hose, this was the start of 60psi fuel pressure in Rangers
But it was slow to react to engine demand, so pressure at the engine could vary widely, 45psi to 75psi, which drives computer nuts, lol

In 2001 and up, a 3 port fuel filter was added, FPR was still in the tank with the pump but not on the pump OUT hose
FPR had return hose from the fuel filter
This stabilized pressure at the engine, 55-65psi

P0171 and 174 means both banks on a V engine needed more fuel added according to O2 sensor feedback
If O2 sensors are more than 12 years old or have over 100k miles then change them, see if those codes go away
Those 2 codes are based on O2 sensor feedback so if sensors are old then false codes

If O2s are newer then could be upper intake air leak or weak fuel pump, needs 60psi running pressure at the engine, there is a test port



P0453 is an EVAP system code so not related to engine operation
EVAP system applies negative air pressure in the gas tank to prevent gasoline fumes from polluting the air when driving(gas sloshing around)
EVAP pressure sensor measures how much negative AIR pressure there is, its not much just enough to hold fumes in