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Replaced the EVAP hoses, the PCV hose to the air intake (no kink now), and the white vacuum hose to the control at the firewall. The defrost vent control thingy works better now.
I also tested the fuel pressure. 30 psi at idle and 40 psi when the vacuum hose is removed from the FPR. When I rev the engine up to 2000 rpms the psi seems to stays steady at about 30 psi. Are these numbers normal? When I was measuring the fuel pressure I noticed after I shut off the engine the pressure started dropping right away. Is that expected?
So I still get code 172 when I do the KOER test. I have been thinking...the computer thinks the engine is running lean but emissions test says it is running rich. Doesn't that mean the computer is wrong? Or in other words, the O2 sensor is not working if it is reporting lean condition when it is really running rich. No?
I might just take it through emissions again since it has been so long since the last time!! It would be nice to see if I have made any improvement.
So I took it through emissions just now, quite a difference...but I still failed.
2 yrs ago: idle - HC 773 (300), CO 8.05 (4.00), Loaded - HC 504 (300) CO 11.86 (3.00)
today: idle - HC 725 (300), CO 7.25 (4.00), Loaded - HC 21 (300) CO 00.00 (3.00)
I passed on the loaded test but failed both HC and CO at idle. The idle numbers improved slightly from last time.
One thing I forgot to mention...when I was measuring the fuel pressure I noticed after I shut off the engine the pressure started dropping right away. Is that expected?
One thing I forgot to mention...when I was measuring the fuel pressure I noticed after I shut off the engine the pressure started dropping right away. Is that expected?
The fuel pressure dropping significantly after shut off suggests that it's bleeding out somewhere, it could possibly be an injector leaking or just a bad check valve in the tank but again it could also be a fuel pressure regulator. A Bad fuel pressure regulator or a leaking fuel injector would also explain the running rich.
Edit, it's possible for the fuel pressure regulator to be leaking fuel into the vacuum lines and still regulate the fuel pressure correctly.
So I took it through emissions just now, quite a difference...but I still failed.
2 yrs ago: idle - HC 773 (300), CO 8.05 (4.00), Loaded - HC 504 (300) CO 11.86 (3.00)
today: idle - HC 725 (300), CO 7.25 (4.00), Loaded - HC 21 (300) CO 00.00 (3.00)
I passed on the loaded test but failed both HC and CO at idle. The idle numbers improved slightly from last time.
Does this shed any light into my issues?
I'm not familiar with the emissions test's or there terms of HC or CO but it would seem you fixed some of the problems, The fact that it's passing under load but failing at idol leads me to think that it's getting fuel that isn't supposed to be there into the intake and the 02sensor and computer can compensate for the extra fuel underload but not while idling.
Replaced the EVAP hoses, the PCV hose to the air intake (no kink now), and the white vacuum hose to the control at the firewall. The defrost vent control thingy works better now.
I also tested the fuel pressure. 30 psi at idle and 40 psi when the vacuum hose is removed from the FPR. When I rev the engine up to 2000 rpms the psi seems to stays steady at about 30 psi. Are these numbers normal? When I was measuring the fuel pressure I noticed after I shut off the engine the pressure started dropping right away. Is that expected?
So I still get code 172 when I do the KOER test. I have been thinking...the computer thinks the engine is running lean but emissions test says it is running rich. Doesn't that mean the computer is wrong? Or in other words, the O2 sensor is not working if it is reporting lean condition when it is really running rich. No?
I might just take it through emissions again since it has been so long since the last time!! It would be nice to see if I have made any improvement.
Yeah it's me again, dug out my old code book that is well-worn and hasn't been used in years and code 172 is definitely a lean code? Have you replaced the O2 sensor yet? I thought you did but I could be confusing this with another thread.
it sounds like the EGR valve is stuck partial open. This would cause the pass at load fail at idle. Pull the vacuum line and test your EGR with a pump make sure it is working properly.
Yes fresh gas (just under a 1/4 tank) and I drove it 12 or so miles on the highway non-stop to the emissions place going about 70mph the whole time. I was the only car there when I got there so no waiting!!
it sounds like the EGR valve is stuck partial open. This would cause the pass at load fail at idle. Pull the vacuum line and test your EGR with a pump make sure it is working properly.
I will look up how to do this. Not sure what type of pump is required.
Also, I have a whoosh or swoosh everytime I turn the engine off. It happens a second or so have the engine shuts off. It has been this way since I bought the truck. I assumed it was normal but maybe this has something to with vacuum?
ok,I just read thru the whole thread.I have a 1994 f-250,5.8 also. Ever since i bought it new,i've always had problems passing emmisions(in Pensylvania this truck only needs a 2 speed idle test).The mechanic said the cat is too large and won't burn the gases up. after the 1st atempt,on the 2nd atempt the emmision machine states to run the engine at 2500 rpms for 3 minutes, after that it always passes,because the cat was red hot and burnt all the excess up. Not sure if that is possible in your state.
I will look up how to do this. Not sure what type of pump is required.
i know for a fact that if you hook a vacuum line to the egr valve nipple while its idling, then suck on the vacuum tube, the truck should die. that's how i test mine. no pump needed.
I attached a vacuum hose (from a spare port of the manifold) to the EGR valve at idle. The engine about shut off instantly. Does this mean it is good?
I also replaced the PCV valve...what a pain! Still getting the 172 code. Maybe I just need to replace the FPR since it doesn't seem to be holding fuel pressure when the engine is shut off.
I also replaced the PCV valve...what a pain! Still getting the 172 code. Maybe I just need to replace the FPR since it doesn't seem to be holding fuel pressure when the engine is shut off.
I've been seconding and suggesting that very idea for a while now.... Might be a good time to look into it.
Edit, it seems after reading you have sort of checked it... Still a good place to to look for your problems but i'm not going to guarantee it will be the answer.
