engine code questions
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From: Charm City
I picked up a new code.
KOEO, 22 ( MAP sensor, this is the new one) and 32
KOER, 32.
I've been looking at the wiring diagram for my truck and there's another slight "difference" between the 5.0 and 5.8 harnesses. Apparently, with the 5.0 ( which is what my truck started out life as, as it's the engine harness that I used) there are some differences to how the orange wire for the HEGO is wired. It shows that the orange wire returns to pin 49 and it's spliced with that lead going to ground in the 5.0 configuration but with the 5.8 configuration, it ties back into the blk/wht lead for the knock sensor which goes back to pin 46. Maybe the PCM is looking for that ground signal from the o2 sensor ?
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From: Eastern Ky
I just ran another test to pull codes after clearing everything last night.
I picked up a new code.
KOEO, 22 ( MAP sensor, this is the new one) and 32
KOER, 32.
I've been looking at the wiring diagram for my truck and there's another slight "difference" between the 5.0 and 5.8 harnesses. Apparently, with the 5.0 ( which is what my truck started out life as, as it's the engine harness that I used) there are some differences to how the orange wire for the HEGO is wired. It shows that the orange wire returns to pin 49 and it's spliced with that lead going to ground in the 5.0 configuration but with the 5.8 configuration, it ties back into the blk/wht lead for the knock sensor which goes back to pin 46. Maybe the PCM is looking for that ground signal from the o2 sensor ?
I picked up a new code.
KOEO, 22 ( MAP sensor, this is the new one) and 32
KOER, 32.
I've been looking at the wiring diagram for my truck and there's another slight "difference" between the 5.0 and 5.8 harnesses. Apparently, with the 5.0 ( which is what my truck started out life as, as it's the engine harness that I used) there are some differences to how the orange wire for the HEGO is wired. It shows that the orange wire returns to pin 49 and it's spliced with that lead going to ground in the 5.0 configuration but with the 5.8 configuration, it ties back into the blk/wht lead for the knock sensor which goes back to pin 46. Maybe the PCM is looking for that ground signal from the o2 sensor ?
BINGO!
Repin the Orange wire, to suit 5.0 shematics, etc and see where you stand...
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From: Charm City
Does this sound correct?
Fleet Owner
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From: Kentucky
I do not have an EVTM for anything older than 1992. I looked through what I had and also looked at the EVTMs Ryan has at Oldfuelinjection.com. I am not seeing anything called out as a difference for the Orange wire, HEGO ground, for a 5.0L versus a 5.8L engine. Electrically Pin 46 and $( are the same reference. The splice, for a 1992 is S137 in the engine harness. I do not think this issue is affecting your mileage.
Stay with the path of resolving what you do know is wrong. Clearly the EVP sensor is not sending out the correct voltage with the EGR closed and I would say it is shy of what the signal should be with the EGR open.
As I noted before the EVP is preloaded by the EGR diaphragm/spring assembly. It is very difficult to break them apart to see which one is the root cause. At the very least you should measure the EVP resistance perhaps the Tomco site has the resistance values?
Cut from my Ford Service Manual:
DTC 32/328 in Key On Engine Off (KOEO) and Key On Engine Running (KOER) indicates that the EGR valve and/or EVP sensor voltage is lower than normal in the closed position. The EVP voltage is less than the closed limit voltage of 0.24 volts. Because of the preload of the EVP sensor it is very difficult to determine whether the EGR valve has malfunctioned or the EVP sensor has an abnormally high resistance.
I assume the Check Engine Light is on because of Code 32? This maybe triggering the PCM to run in limp mode which will seriously affect MPGs.
Stay with the path of resolving what you do know is wrong. Clearly the EVP sensor is not sending out the correct voltage with the EGR closed and I would say it is shy of what the signal should be with the EGR open.
As I noted before the EVP is preloaded by the EGR diaphragm/spring assembly. It is very difficult to break them apart to see which one is the root cause. At the very least you should measure the EVP resistance perhaps the Tomco site has the resistance values?
Cut from my Ford Service Manual:
DTC 32/328 in Key On Engine Off (KOEO) and Key On Engine Running (KOER) indicates that the EGR valve and/or EVP sensor voltage is lower than normal in the closed position. The EVP voltage is less than the closed limit voltage of 0.24 volts. Because of the preload of the EVP sensor it is very difficult to determine whether the EGR valve has malfunctioned or the EVP sensor has an abnormally high resistance.
I assume the Check Engine Light is on because of Code 32? This maybe triggering the PCM to run in limp mode which will seriously affect MPGs.
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From: Charm City
I do not have an EVTM for anything older than 1992. I looked through what I had and also looked at the EVTMs Ryan has at Oldfuelinjection.com. I am not seeing anything called out as a difference for the Orange wire, HEGO ground, for a 5.0L versus a 5.8L engine. Electrically Pin 46 and $( are the same reference. The splice, for a 1992 is S137 in the engine harness. I do not think this issue is affecting your mileage.
Stay with the path of resolving what you do know is wrong. Clearly the EVP sensor is not sending out the correct voltage with the EGR closed and I would say it is shy of what the signal should be with the EGR open.
As I noted before the EVP is preloaded by the EGR diaphragm/spring assembly. It is very difficult to break them apart to see which one is the root cause. At the very least you should measure the EVP resistance perhaps the Tomco site has the resistance values?
I assume the Check Engine Light is on because of Code 32? This maybe triggering the PCM to run in limp mode which will seriously affect MPGs.
Stay with the path of resolving what you do know is wrong. Clearly the EVP sensor is not sending out the correct voltage with the EGR closed and I would say it is shy of what the signal should be with the EGR open.
As I noted before the EVP is preloaded by the EGR diaphragm/spring assembly. It is very difficult to break them apart to see which one is the root cause. At the very least you should measure the EVP resistance perhaps the Tomco site has the resistance values?
I assume the Check Engine Light is on because of Code 32? This maybe triggering the PCM to run in limp mode which will seriously affect MPGs.
I have a new EGR valve and EVP sensor, I just didn't want to install them until I was 100% sure those components are bad. Now that I'm getting a MAP sensor code, I'm thinking that I will replace that one first and then re-test to see where I'm at.
What do you think would be the cause of the EVP voltage not raising with the engine temp? This has me completely baffled. Hell, it's been 20+ years since I've even messed with OBD1.
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From: Kentucky
I never had a CEL come on, I just really couldn't believe that the mileage this truck was getting was the best it could do so I checked for codes and this is what has led me to where I'm at right now.
I have a new EGR valve and EVP sensor, I just didn't want to install them until I was 100% sure those components are bad. Now that I'm getting a MAP sensor code, I'm thinking that I will replace that one first and then re-test to see where I'm at.
What do you think would be the cause of the EVP voltage not raising with the engine temp? This has me completely baffled. Hell, it's been 20+ years since I've even messed with OBD1.
I have a new EGR valve and EVP sensor, I just didn't want to install them until I was 100% sure those components are bad. Now that I'm getting a MAP sensor code, I'm thinking that I will replace that one first and then re-test to see where I'm at.
What do you think would be the cause of the EVP voltage not raising with the engine temp? This has me completely baffled. Hell, it's been 20+ years since I've even messed with OBD1.
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From: Charm City
Ok, I understand what you're saying. Do you have any thoughts as to why the voltage at the EVP didn't come up from .24V during the engine warm up? Is it not supposed to? I'm sorta stuck with this at the moment, I don't want to install a brand new EGR and EVP if there's another issue. I'm on the way to buy a MAP sensor since I got a code for that yesterday.
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From: Kentucky
The EVP (EGR Valve Position) sends EGR position feedback to the PCM. The EGR should never be activated until the engine is warmed up and running under cruise/light load conditions. Therefore regardless if the engine is cold or warm the EVP signal value should remain the same with the engine running at idle. The only time the EVP signal should change is when the PCM (computer) commands the EGR to open by pulse width modulating (turning on/off the EVR several times a second) the EVR (EGR Valve Regulator) under the conditions I listed before.
I use a cheap DVM that can also measures frequency to test my MAP sensor. I hooked up a handheld vacuum pump/gauge to apply a measured amount of vacuum to the MAP sensor vacuum port. The meter displays the frequency output that is sent to the PCM. That you now if the MAP is good or not. I purchased both tools at Harbor Freight, they have paid for themselves time again. It eliminates a lot of guesswork and needless part swapping.
I use a cheap DVM that can also measures frequency to test my MAP sensor. I hooked up a handheld vacuum pump/gauge to apply a measured amount of vacuum to the MAP sensor vacuum port. The meter displays the frequency output that is sent to the PCM. That you now if the MAP is good or not. I purchased both tools at Harbor Freight, they have paid for themselves time again. It eliminates a lot of guesswork and needless part swapping.
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From: Charm City
The EVP (EGR Valve Position) sends EGR position feedback to the PCM. The EGR should never be activated until the engine is warmed up and running under cruise/light load conditions. Therefore regardless if the engine is cold or warm the EVP signal value should remain the same with the engine running at idle. The only time the EVP signal should change is when the PCM (computer) commands the EGR to open by pulse width modulating (turning on/off the EVR several times a second) the EVR (EGR Valve Regulator) under the conditions I listed before.
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From: Charm City
OK, the new MAP sensor is in place along with the EGR valve. As I looked very closely at the EGR I could see ( and feel) where the upper part where that has the vac nipple was loose with the lower body. I removed it from the intake and when I had it in my hands I could physically wiggle to the 2 halves, I'm pretty sure it's NOT supposed to do that.
I re-used the EVP at this time, just to see what kind of voltage readings I get. I get the back probe leads in place, I find 4.9V on one side and .34V on the other side. I start the truck, it immediately started and idled much smoother but the voltage readings seem to be high- it's been between .34V- .37V. The truck is warming up right now, I'll go back out and check in a few minutes.
I re-used the EVP at this time, just to see what kind of voltage readings I get. I get the back probe leads in place, I find 4.9V on one side and .34V on the other side. I start the truck, it immediately started and idled much smoother but the voltage readings seem to be high- it's been between .34V- .37V. The truck is warming up right now, I'll go back out and check in a few minutes.
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From: Charm City
Fleet Owner
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From: Kentucky
OK, the new MAP sensor is in place along with the EGR valve. As I looked very closely at the EGR I could see ( and feel) where the upper part where that has the vac nipple was loose with the lower body. I removed it from the intake and when I had it in my hands I could physically wiggle to the 2 halves, I'm pretty sure it's NOT supposed to do that.
I re-used the EVP at this time, just to see what kind of voltage readings I get. I get the back probe leads in place, I find 4.9V on one side and .34V on the other side. I start the truck, it immediately started and idled much smoother but the voltage readings seem to be high- it's been between .34V- .37V. The truck is warming up right now, I'll go back out and check in a few minutes.
I re-used the EVP at this time, just to see what kind of voltage readings I get. I get the back probe leads in place, I find 4.9V on one side and .34V on the other side. I start the truck, it immediately started and idled much smoother but the voltage readings seem to be high- it's been between .34V- .37V. The truck is warming up right now, I'll go back out and check in a few minutes.
The EVP should read between 0.24 and 0.67volts at idle with a closed EGR valve.
You are now within the typical range the EVP signal should be. Sounds like the EGR valve was pretty much toast. Good find.
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From: Charm City
Thanks again! I just went for a 10 mile test run. I have no way of knowing right now if the MPG's went up but I can tell you that the driveability has definitely improved. The truck idles very smoothly at cold idle, it revs through the RPM much smoother and it just feels and sounds better. It would always have a hard time getting past 3K RPM on the freeway when down shifting, it always felt like it just 'over fueled' (like a carb'd engine that runs way too rich) and sluggish. Now it drives like it should so hopefully I have it sorted out. I'm going to eat some lunch then go back outside, clear the stored codes and run it again and re-check to see if I have anything stored.
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From: Charm City
Here's the last results of pulling codes.
KOEO, 85, 95. Code 85, no big deal to me- the purge solenoid isn't present. code 95- I know that the front tank fuel pump sounds like it's on it's last legs but I've been only using the rear tank. Who knows.. I'll deal with it later when I replace the front pump assembly.
KOER, 11
hell yes!!
So, to recap what the repair was- the MAP sensor and EGR valve were replaced, EVP sensor was re-used because it seemed to be working properly. The orange wire to the HEGO was left where it was within the 5.0 harness, both pins turned out to be PCM grounds, nothing to be gained by swapping out which ground the orange wire went to.
Thanks again to rla2005 for the help along with everyone else who shared their ideas.
KOEO, 85, 95. Code 85, no big deal to me- the purge solenoid isn't present. code 95- I know that the front tank fuel pump sounds like it's on it's last legs but I've been only using the rear tank. Who knows.. I'll deal with it later when I replace the front pump assembly.
KOER, 11
hell yes!!So, to recap what the repair was- the MAP sensor and EGR valve were replaced, EVP sensor was re-used because it seemed to be working properly. The orange wire to the HEGO was left where it was within the 5.0 harness, both pins turned out to be PCM grounds, nothing to be gained by swapping out which ground the orange wire went to.
Thanks again to rla2005 for the help along with everyone else who shared their ideas.