HELP IM STUCK
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Joined: Feb 2019
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From: Oakdale ca
HELP IM STUCK
1996 ford ranger 3.0 v6 200xxx miles manual trans. Runs and drives no problem. I’m getting a P0172 and p0175(both rich bank one and two). It also is hesitant on the gas. Can’t find a vacuum leak. Brand new MAF, new coolant temp sensor and brand new thermostat. Brand new charcoal canister and charcoal canister relay. New egr valve. New throttle position sensor. Stock intake with brand new filter. Also installed an aftermarket muffler (code was before this however)
I have no idea what it could be. I need to pass smog but it will not because of these reoccurring codes. Please help
I have no idea what it could be. I need to pass smog but it will not because of these reoccurring codes. Please help
Welcome to the forum
First, are there signs of actual Rich running?
Grey/black Smoke from tail pipe
Pull out a couple of spark plugs and see if they are a darker brown color
Do you notice a DROP in MPG
Lean and Rich codes are based on Open Time for fuel injectors
O2 sensors only see Oxygen, not fuel, O2 sensors generate their own voltage once they are warmed up, .1v is high oxygen level(Lean), .9v is low oxygen level(Rich)
Computer calculates injector open time based on RPM, Throttle position, MAF data, and air temp, this calculation is 0 STFT(short term fuel trim)
Say computer calculates 0 STFT to be 100ms(milliseconds) open time for each injector
Injector is opened for 100ms and then computer watches O2 sensor voltage, if its .1(Lean) then computer changes STFT to +2% and opens injectors for 102ms
If O2 voltage is .9 then STFT change to -2% and open time is 98ms
If still .9 then it changes to -4%, then -6%, then -8% and so on until O2 shows average of ,4volt, the sweet spot for correct oxygen level in the exhaust
For a Rich code to be set Calculated STFT needs to be off by -15% to -20%, and over a period of a few minutes, same for lean codes, +15-20%
Common cause of Rich codes on 1997 and earlier Rangers was a leaking Fuel Pressure Regulator(FPR), 1998 and up used a different system
On the engine, passenger side, you should see the FPR, it has a Fuel line connected AND vacuum hose
From drivers side frame rail you will see 2 fuel lines coming up and running to the engine, one is the IN from fuel pump/filter, it connects to the fuel rail, drivers side
The other is the Return fuel line, it connects to the FPR, it allows extra fuel to flow back to the gas tank, maintaining 30psi pressure for the fuel injectors
If it leaks internally the Vacuum hose on the FPR sucks extra fuel into the intake, causing Rich codes on BOTH banks
So check that vacuum hose for signs of gasoline, if found replace FPR
You check of the EVAP system was smart, EVAP system sucks gasoline fumes from the gas tank, using engine vacuum, and burns them in the engine, but slowly, if the EVAP solenoid gets stuck open then fumes are sucked in to fast and you get Rich codes.
You will see the EVAP solenoid in the drivers side engine bay, connects to the canister and an intake manifold vacuum port, you can pull off the hose at the canister and then start the engine, there should be NO vacuum on that hose just after start up, if there is then EVAP solenoid is stuck open.
If FPR gets stuck closed, or return line gets blocked, fuel pressure will get too high, this is VERY rare
You need to test fuel pressure at its test port, on the engine passenger side, is what looks like a tires air valve, because it is, its a shcrader valve and works the same way, engine running should show steady 30-35psi pressure at any RPM
Blocked exhaust would show as a lack of power at higher RPMs, like engine is "hitting a wall" at highway speeds and exhaust would backup
Leaking fuel injector would only make ONE bank Rich
Failing O2 sensor would be the same, only ONE bank would show Rich
First, are there signs of actual Rich running?
Grey/black Smoke from tail pipe
Pull out a couple of spark plugs and see if they are a darker brown color
Do you notice a DROP in MPG
Lean and Rich codes are based on Open Time for fuel injectors
O2 sensors only see Oxygen, not fuel, O2 sensors generate their own voltage once they are warmed up, .1v is high oxygen level(Lean), .9v is low oxygen level(Rich)
Computer calculates injector open time based on RPM, Throttle position, MAF data, and air temp, this calculation is 0 STFT(short term fuel trim)
Say computer calculates 0 STFT to be 100ms(milliseconds) open time for each injector
Injector is opened for 100ms and then computer watches O2 sensor voltage, if its .1(Lean) then computer changes STFT to +2% and opens injectors for 102ms
If O2 voltage is .9 then STFT change to -2% and open time is 98ms
If still .9 then it changes to -4%, then -6%, then -8% and so on until O2 shows average of ,4volt, the sweet spot for correct oxygen level in the exhaust
For a Rich code to be set Calculated STFT needs to be off by -15% to -20%, and over a period of a few minutes, same for lean codes, +15-20%
Common cause of Rich codes on 1997 and earlier Rangers was a leaking Fuel Pressure Regulator(FPR), 1998 and up used a different system
On the engine, passenger side, you should see the FPR, it has a Fuel line connected AND vacuum hose
From drivers side frame rail you will see 2 fuel lines coming up and running to the engine, one is the IN from fuel pump/filter, it connects to the fuel rail, drivers side
The other is the Return fuel line, it connects to the FPR, it allows extra fuel to flow back to the gas tank, maintaining 30psi pressure for the fuel injectors
If it leaks internally the Vacuum hose on the FPR sucks extra fuel into the intake, causing Rich codes on BOTH banks
So check that vacuum hose for signs of gasoline, if found replace FPR
You check of the EVAP system was smart, EVAP system sucks gasoline fumes from the gas tank, using engine vacuum, and burns them in the engine, but slowly, if the EVAP solenoid gets stuck open then fumes are sucked in to fast and you get Rich codes.
You will see the EVAP solenoid in the drivers side engine bay, connects to the canister and an intake manifold vacuum port, you can pull off the hose at the canister and then start the engine, there should be NO vacuum on that hose just after start up, if there is then EVAP solenoid is stuck open.
If FPR gets stuck closed, or return line gets blocked, fuel pressure will get too high, this is VERY rare
You need to test fuel pressure at its test port, on the engine passenger side, is what looks like a tires air valve, because it is, its a shcrader valve and works the same way, engine running should show steady 30-35psi pressure at any RPM
Blocked exhaust would show as a lack of power at higher RPMs, like engine is "hitting a wall" at highway speeds and exhaust would backup
Leaking fuel injector would only make ONE bank Rich
Failing O2 sensor would be the same, only ONE bank would show Rich
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From: Oakdale ca
So I’ll definitely check that out, I took the truck to a mechanic to get it diagnosed and they couldn’t find any vacuum leaks and they said it was an ecu(which I find hard to believe considering this is my one and only issue with the truck). I also took off my intake manifold last night to check for vacuum leaks, clean it up a bit and also I changed all of the rings on the injectors while it was off. I didn’t see any signs of leaking on the injectors but they were pretty gunned up. Also all the hoses that I was able to by removing the intake manifold were in good shape. No cracks or signs of irregular anything really.
What would make the engine rev between shifts? I understand it’s a common problem with rangers but I can’t seem to track down what’s making it happen
also yes I have seen a lack of
mpg, as for the smoke I haven’t seen any buy ill
keep a look out for white/grey/black smoke
What would make the engine rev between shifts? I understand it’s a common problem with rangers but I can’t seem to track down what’s making it happen
also yes I have seen a lack of
mpg, as for the smoke I haven’t seen any buy ill
keep a look out for white/grey/black smoke
Last edited by Ethan_pollock; Feb 15, 2019 at 10:13 AM.
Vacuum leaks cause Lean Codes
ECU(PCM) is not out of the question, although it is a last resort
Only reason and whole purpose of the PCM is to calculate fuel trims on the fly, that 95% of what it does
Rich codes are on the rare side, not common like Lean codes
Do you have a code reader than can see live data?
i.e. what is LTFT(long tern fuel trim) showing
The REVing with clutch pedal down can also point to PCM issue, you can call Ford dealer and see if your VIN number has a software update avaialble
ECU(PCM) is not out of the question, although it is a last resort
Only reason and whole purpose of the PCM is to calculate fuel trims on the fly, that 95% of what it does
Rich codes are on the rare side, not common like Lean codes
Do you have a code reader than can see live data?
i.e. what is LTFT(long tern fuel trim) showing
The REVing with clutch pedal down can also point to PCM issue, you can call Ford dealer and see if your VIN number has a software update avaialble
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Joined: Feb 2019
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From: Oakdale ca
I have a code reader but unfortunately it cannot see live data. I checked my oil as well and it does not smell like gas as the fpr would indicate. I’m going to check my return line and other fuel related things. I’ll definitely look into the pcm today though and I’ll see if I can track down the issue
Why would leaking FPR get fuel into the oil?
Engine wouldn't run if it was leaking that bad, lol
Check its vacuum hose
Check Computers sanity
Unplug MAF sensor and run engine, should set a MAF code
Unplug IAT(intake air temp) sensor, upper intake manifold, should also set a code
You can unhook one battery cable for 5 minutes, that will clear PCM's KAM(keep alive memory), like radio presets and clock, which will also be cleared, lol.
KAM stores "learned info" like IAC valve and TPS settings so engine idle may wander a bit after restart but should settle down after full warm up and cool down
Engine wouldn't run if it was leaking that bad, lol
Check its vacuum hose
Check Computers sanity
Unplug MAF sensor and run engine, should set a MAF code
Unplug IAT(intake air temp) sensor, upper intake manifold, should also set a code
You can unhook one battery cable for 5 minutes, that will clear PCM's KAM(keep alive memory), like radio presets and clock, which will also be cleared, lol.
KAM stores "learned info" like IAC valve and TPS settings so engine idle may wander a bit after restart but should settle down after full warm up and cool down
Thread Starter
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Member
Joined: Feb 2019
Posts: 5
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From: Oakdale ca
I’m gonna get ahold of the dealership and see if there is a update available, the only reason I’m hesitant to unplug the battery is because I need to get it smogged and they will make you drive it around until your drive cycle is complete if I do that/: it’s a pain in the butt, also I’d have to wait until that drive cycle is complete to see if the check engine light is going to just come back on. And I guess if your oil smells of gas it could be a sign of a bad fpr, there are other ways to figure it out that I’m going to check for sure but that one only took about 10 seconds so I tried it first
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