1997 Ford Ranger 4.0l CE LIGHT

[BFAB]

Absolutely STUMPED on my Ford Ranger.... 1997 4.0l Auto with 5 Speed.


I've had the truck for almost 7 months now have been battling a check engine light now the entire time.. and after reading and reading and reading I have change countless parts and still getting an annoying light.

I had a super intermittent light for quite some time. Thought we had it gone after doing all these things and then went and smogged it and it passed.. NOW MIND YOU i have driven this thing over 4k miles offroad..no issues other than in the beginning it would randomly die when you hit the throttle or let off..

But now the light as soon as I clear it come back instantly. I have checked everything we have done and have the same codes as we did before the smog test.

PO171 BANK 1 TOO LEAN
PO174 BANK 2 TOO LEAN
PO443 EVAP PURGE CONTROL


So far I've changed/done the following..
-All 3 O2 Sensors changed
-Cleaned/Tested MAF
-ALL filters (oil filter, fuel filter, air, fuel pump screen)
-New fuel pump (original tested fine on pressure)
-Idle Air Control Valve
-Cleaned/tested TBPS
-Intake plenum gaskets and upper intake gaskets
-Fuel Cap and filler neck
-Purge control valve and sensor are brand new
-Plugs and Wires


Any ideas before I gut this thing and add some HP via LS MOTOR?

 

[the bodj]

What brand O2 sensors did you use? I've had three faulty Bosch sensors in a row. Switched to NTK

 

[Exploder_M]

Sounds to me like a vacuum leak somewhere. Have you sprayed carb and choke around the intake manifold upper and lower to see if the engine RPMs raise slightly?

 

[BFAB]

Sounds to me like a vacuum leak somewhere. Have you sprayed carb and choke around the intake manifold upper and lower to see if the engine RPMs raise slightly?

yes and no change.


Smog shop said they ran a smoke test and said it al checked out. I've also already done all new upper and lower intake gaskets etc.

 

[Crusty]

What brand did you use for the Purge control valve and sensor?

Did it go from intermittent to all the time after you swapped these parts or before?

I chased a Fuel Delivery issue, tested everything, pump, pressure......and it was just 3 relays that needed to be replaced D'oh!

 

[85Yota]

I'm not sure what issue @theycallmeWALLY had with his ranger but he had to change his ECU.

 

[96f-u250]

Check vacuum lines, and or replace them anyways with good rubber hose.

 

[zachwabbit]

Did you check your harness? Might be able to get away with changing a couple pigtails at the sensors before you have to change the whole thing

 

[cbrewer22]

Did you check the small 4inch rubber hose under the throttle body?

 

[theycallmeWALLY]

I'm not sure what issue @theycallmeWALLY had with his ranger but he had to change his ECU.

Yeah. Mine was a computer issue but doesn't sound the same. Sounds like a sensor issue. Find someone with a good scan tool to see what's not falling into parameters while running. Maybe IAC?

 

[BFAB]

Yeah. Mine was a computer issue but doesn't sound the same. Sounds like a sensor issue. Find someone with a good scan tool to see what's not falling into parameters while running. Maybe IAC?

IAC is brand new as well.


I used Bosch O2's on the truck..


Hose on bottom of the TB was good as well.


I can spray starting fluid all over the motor and zero change in rpm etc.

 

[bullnerd]

I was gonna say run a scanner while driving/under load but if it’s instant that won’t help.

Healthy 12 volts to the fuel pump?

Fuel pump ground?

 

[Exploder_M]

Not sure if you have this connector but, Have you checked this connector here? I know these were a problem and created some weird electrical Gremlins