When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
So if it is not the MAP sensor, what could cause such high readings in ALL areas? I just looked the engine over and I found some EVAP lines going to the canister that might be suspect, but thats about it. Even more confusing is my truck seems to run fine.
My 92 with a 5.0 5 speed was running really rich when i bought it. Didn't throw any codes. Was no fuel in the vacuum line to the fuel pressure regulator. Changed a lot of stuff including the O2 sensor. After I replaced the fuel pressure regulator it fixed it. Running great since then. That was 2008. I would try the fpr
I second checking The fuel pressure regulator, cycle the key on-off and pull the vacuum line off the fuel pressure regulator and see if there's any fuel coming out of the vacuum port.
Throwing parts will only compound it. Find the issue first.
If you start blindly replacing parts. You don't know if you fixed
it with one and broke it with the other. AND it will drive the cost
to fix the problem up.
pull codes. this is what needs to happen. nothing else. pull codes. troubleshooting is a process. you can't jump to the end and start replacing parts blindly.
Throwing parts will only compound it. Find the issue first.
If you start blindly replacing parts. You don't know if you fixed
it with one and broke it with the other. AND it will drive the cost
to fix the problem up.
pull codes. this is what needs to happen. nothing else. pull codes. troubleshooting is a process. you can't jump to the end and start replacing parts blindly.
I am not skipping steps. This is two year adventure. I replaced the O2 sensor based off the only code I saw. It went away and has never come back. I am really trying to do this logically...
Does the check engine light always come on if there are fault codes? The check engine light is off.
Or does the truck throw codes and not report it to the driver?
Even with the check engine light off, your truck has a memory that will store codes. I believe the code you are lookong for is 111, where all systems pass and there are no trouble codes.
I am not skipping steps. This is two year adventure. I replaced the O2 sensor based off the only code I saw. It went away and has never come back. I am really trying to do this logically...
Does the check engine light always come on if there are fault codes? The check engine light is off.
Or does the truck throw codes and not report it to the driver?
thanks.
You you can get codes without getting a CEL to light up.
Also just because it says there is a problem with an O2 sensor
it does not mean that is the problem part. All it is telling is
the info from that sensor is out of range. There a few things that
can cause that. The CO and HC says your over-fueling and that should
also kick a code for an O2. Find the pinpoint testing steps and look
for things that can cause high HC and CO along with O2 sensor out
of range.
You you can get codes without getting a CEL to light up.
Also just because it says there is a problem with an O2 sensor
it does not mean that is the problem part. All it is telling is
the info from that sensor is out of range. There a few things that
can cause that. The CO and HC says your over-fueling and that should
also kick a code for an O2. Find the pinpoint testing steps and look
for things that can cause high HC and CO along with O2 sensor out
of range.
Just so you know, I replaced the O2 sensor in 2012 and have not had any CEL come back. Granted I haven't driven it much this past year... My problem now is failing emissions.
You say a few things can cause this issue...mind sharing? All I am looking for is some suggestions from those that know Fords best. I have exhausted my very limited knowledge on engines. I was hoping that there might be those who have had this same issue.
BTW, I just checked the FPR and there is no fuel coming out the vacuum port. Not really surprised but it is data at least. I will go check the codes again.
When my truck was running really rich there were no codes and no fuel in the vacuum line to the fuel pressure regulator. But after I change the fpr it didn't run rich anymore and still runs great.
Ok, I did the KOER test and got CEL 172!! I thought it was fixed...boy was I wrong!
Could bad EVAP lines going from the throttle body to the canister cause this problem? They look old and brittle and might have some hairline cracks. I will replace all those for sure. All the other vacuum lines look real good.
Also, I just noticed the rubber hose from the oil tube to the air intake housing was kinked real bad.
And finally, there is something like an air diverter or something (between the throttle body and the coil) that has an air outlet that does not have a hose going to it. Is there supposed to be a hose? Does it go to the air intake houseing? I don't have the stock housing, the PO put a K&N system on. I was thinking about tee-ing that in with the hose coming from the oil tube to the air intake housing.
"172 - HEGO sensor circuit indicates system lean (right side)"
Originally Posted by LCconvert
there is something like an air diverter or something (between the throttle body and the coil) that has an air outlet that does not have a hose going to it. Is there supposed to be a hose? Does it go to the air intake houseing?
Do to the fact that I have not dealt with a gas engine in quite some time
I am more than a bit rusty. I tend to be diesel, gas carbureted non-computerized
and aircraft.
Also getting all the hoses in a non-leaking state will help. Also check and make
sure that the throttle body has not gotten loose some how. Check all rubber
after the throttle plate.
Also have you checked the fuel pressure at the port on the fuel manifold?
