EGR Help Please
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Laughing Gas
Joined: Jul 2004
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EGR Help Please
Hope I posted this in the right forum....
I just got my 96 f 150 extended cab sb 302 auto. The engine light is on and the code is p401 that is EGR valve so I replaced it and the light is still on. Well I went out and bought a vacum guage and there is no vacum at the egr valve at all. So I traced the green line back to the other side of motor and it goes to the bottom of this do dad beside the coil ( lack of better word please anyone know the name...lol) and right below it is a black vacumn line so I checked that for vacumn and it has about 17 at idle. What I am askin is would this piece or part be the problem because it looks like vacum goes into it but does not come out to feed the egr valve. Sorry if I confused you all with my lack of knowledge but my 79 is so much easier to work on, any help appreciated...
I just got my 96 f 150 extended cab sb 302 auto. The engine light is on and the code is p401 that is EGR valve so I replaced it and the light is still on. Well I went out and bought a vacum guage and there is no vacum at the egr valve at all. So I traced the green line back to the other side of motor and it goes to the bottom of this do dad beside the coil ( lack of better word please anyone know the name...lol) and right below it is a black vacumn line so I checked that for vacumn and it has about 17 at idle. What I am askin is would this piece or part be the problem because it looks like vacum goes into it but does not come out to feed the egr valve. Sorry if I confused you all with my lack of knowledge but my 79 is so much easier to work on, any help appreciated...
Freshman User
Joined: Mar 2002
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That box that feeds the erg valve is a vent solinoid. There should be vaccum going into it. It is normal for vaccum to not be going to the erg all the time. Normaly the valve works when the engine is reved up or under a load. I have seen this problem before. For starters you should have about 21 inches of vaccum at idle. The 17 inches is low. Check your vaccum canister(tomatoe can), make sure there are no holes in it(from rust). I have seen holes in those before and it causes low vaccum and causes the erg code to come up because there is not enough vaccum in the system to open the valve. I think the code was "low ERG flow". If that is not the problem, the only other thing i can think of is the erg position sensor is reading wrong. Is that the only code in the ECM? ANd did you reset the ECM when you changed the valve?
hope this helps
kyle
hope this helps
kyle
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Laughing Gas
Joined: Jul 2004
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Ok i checked the vacum and canister it looks fine and I rechecked the vacumn at the vent selenoid and it is a solid 20 maybe a hair more. I did reset computer after changing egr. Yes the code is low egr flow. I put a vacumn guage at the egr and rev motor or try to put a load on it and nothing. If I take my test light to see if there is power to the vent selenoid there is at the red wire. If I put my test light in the brown wire side it will light up but kill the engine. If i put a vacum guage at the egr and then put the test light on the brown wire side I suddenly get about 16 of vacumn to the egr valve. Any suggestions.....
Last edited by Fair 96; Jul 25, 2004 at 11:02 AM.
Freshman User
Joined: Mar 2002
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Ok, the reason your eninge dies when you put the test light to the brown wire is becuase the brown is a ground wire that comes from the ECM and is used to open the selenoid to allow vaccum to get to the erg. so when you put the test light on the brown wire is opened the selenoid fully and thus opened your erg fully, that sudden rush of exhaust going back into the intake is enough to snuff out the engine. That is also why you got vaccum at the erg when you jumped the brown wire. The test light acted like a direct wire being jumped to the selenoid.
For the ecm to read erg flow, it uses the MAF and the O2 sensor. The MAF sensor should see a drop in air entering the engine. the O2 sensor should see the exhaust lean out for a short period. Now i cant say for sure if your O2 or MAF sensors are broken, but it is a place to start looking. When was the last time you O2 was replaced?
that's all i can say for now
kyle
For the ecm to read erg flow, it uses the MAF and the O2 sensor. The MAF sensor should see a drop in air entering the engine. the O2 sensor should see the exhaust lean out for a short period. Now i cant say for sure if your O2 or MAF sensors are broken, but it is a place to start looking. When was the last time you O2 was replaced?
that's all i can say for now
kyle
Senior User
Joined: Jul 2004
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From: Il.
grounding the vent sol. and the engine dies tells me the egr valve is capable of working.
my info says that your truck has an "dpfe sensor" a metallic colored sensor with a electrical conn. and two hoses that make there way to the ex. manifold. probally one or both of the hoses are bad or the dpfe sensor is bad.
my info says that your truck has an "dpfe sensor" a metallic colored sensor with a electrical conn. and two hoses that make there way to the ex. manifold. probally one or both of the hoses are bad or the dpfe sensor is bad.
Senior User
Joined: Jul 2004
Posts: 141
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From: Il.
egr
look on ex. manifold for the 2 hoses i talked about and follow them to the sensor
the sensor is metal about 2" by 5" about half inch thick. good luck
the sensor is metal about 2" by 5" about half inch thick. good luck
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Elder User
Joined: Jan 2000
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From: Gravel Switch, KY
Not intending to hijack the thread but.....Yes I am. My 93 F350 w/460 is getting codes 31-34. All having to do with the same issues the author of this thread is describing. The EGR valve operates when vacuum is applied directly to it and it doesn't leak down. I spliced in a "T" and ran a vacuum gauge into the cab to watch as I drove the truck. There is perhaps .5" of vacuum all the time and the most it ever pulled was about 1".
I removed the solenoid from the truck and put a vacuum hose on the intake side of the solenoid and applied vacuum. It has a small/medium leak. Is this normal? Specs call for 20-70 ohms and the solenoid itself is within this range. There is a device that plugs in between the solenoid and the harness that changes the ohms to about 130. What is that all about?
DannyP
I removed the solenoid from the truck and put a vacuum hose on the intake side of the solenoid and applied vacuum. It has a small/medium leak. Is this normal? Specs call for 20-70 ohms and the solenoid itself is within this range. There is a device that plugs in between the solenoid and the harness that changes the ohms to about 130. What is that all about?
DannyP
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Senior User
Joined: Jul 2004
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From: Il.
hijack
Hi Danny, I think the sol. is ok. the codes sound like the egr valve is stuck open a little bit(common) i would remove the valve, remove the evp sensor from the valve, put the sensor to the valve just tll you feel the stem of the evp pushing on the inside of the valve.there should be about a 1/8 in. gap between the sensor and the valve,any more and the valve is stuck open,you can try cleaning it but will probally wind up replacing it and the evp sensor. hope this helps.
Elder User
Joined: Jan 2000
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From: Gravel Switch, KY
Gary B: I would assume there should be no vacuum getting past the solenoid to the EGR valve at idle, yet there is a small amount. Wouldn't the slight amount of vacuum I am reading all the time, even at idle, cause the EGR valve not to seat properly? Shouldn't I have seen more than 1" of vacuum under part throttle loaded conditions as I test drove the truck? This is what was leading me to question the EGR solenoid. Since I removed the solenoid I am currently running with no EGR at all. Maybe it's just psychosomatic but it seems to idle a bit smoother.
DannyP
DannyP
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Laughing Gas
Joined: Jul 2004
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Good news so far
The DPFE is on the front of the intake manifold and the lines run down to the EGR tube. I replaced it and the 2 silecone lines and so far after 3 test drives and about 25 miles no light yet.... The Ford people told me that that aluminum or metal gets corroded and it then gets into the DPFE making it not work right. Mine was very corroded at both lines. Anyway the replacement from Ford is redesigned and is plastic to take care of that problem. I went to check autozones and I believe it is metal so I spent the extra 20.00 and went with the Ford part.... By the way the replacement silecone hoses are 69.00 but if you tell them to sell you the stuff from their bulk roll you can get it for about 8.00. Well thanks alot Gary and hopefully I wont be back on here tomarrow saying my light came back on...LOL.. Although it would not suprise me , being Mr. Lucky and all...
The DPFE is on the front of the intake manifold and the lines run down to the EGR tube. I replaced it and the 2 silecone lines and so far after 3 test drives and about 25 miles no light yet.... The Ford people told me that that aluminum or metal gets corroded and it then gets into the DPFE making it not work right. Mine was very corroded at both lines. Anyway the replacement from Ford is redesigned and is plastic to take care of that problem. I went to check autozones and I believe it is metal so I spent the extra 20.00 and went with the Ford part.... By the way the replacement silecone hoses are 69.00 but if you tell them to sell you the stuff from their bulk roll you can get it for about 8.00. Well thanks alot Gary and hopefully I wont be back on here tomarrow saying my light came back on...LOL.. Although it would not suprise me , being Mr. Lucky and all...