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Discussion Starter #1
i'm a new guy here and hope i am posting in the correct forum.

i just inherited a '95 thunderbird with the 4.6l. the check engine light was on with a p1407, no egr flow detected code. after some research, i found it was common for the egr passages to get closed by carbon buildup. i pulled the upper intake elbow off and the passages were completely closed off by carbon. i cleaned it up and reassembled it. after a 500+ mile road trip, the cel never came back on so i figured it was fixed.

i took it to get smogged so i could change the title into my name. it failed with the following numbers:

15 mph
HC: measured= 55, max= 57
CO: measured= .16, max= .33
NO: measured= 508, max 479

25 mph
HC: measured= 29, max= 33
CO: measured= .12, max= .31
NO: measured= 289, max 487

the smog tech suspected the egr was still plugged or not working at all. he put vacuum on the egr valve and the motor didn't slow down at all. he said it should almost die. i started to think that i didn't clean down into the deep hole in the intake that goes to the erg valve. i took it all apart and notice that there was still carbon in there. this time i cleaned it out real good. i put vacuum on the egr vavle while it was apart. the first time i put vacuum on it, i heard a distinctive "pop" like the valve had actually freed up and moved. i puddled up some carb cleaner down in the egr passage of the intake and put vacuum on the valve again. the carb cleaner drained away so i know the valve is at least partially opening now. i did this several times until my puddle of carb cleaner stayed clean. i then reassembled it.

now when i put vacuum on the egr valve, the motor definatly slows down but does not almost stall like i have been told it should. i don't know if i should go and pay for the pretest again at this point or if it still sounds like the egr is not opening enough.

one more thing that i noticed during the smog, while the car was on the dyno at a steady 15 mph, it emitted a cloud of smoke for just a few seconds. it didn't look or smell like burning oil smoke. it was darker color and i honestly don't even know how to describe the smell. maybe just like thick exhaust.

the car is in great shape and seems to run great. it has had all it's oil changes done on time. it has even had all it's scheduled maintenance done on time at the dealer since it was new. it now has 170k miles on it.
 

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It doesn't sound like your EGR problem is fixed yet. The motor should stall at idle if you fully open the EGR valve. You want the intake to be as clean as the pictures in this thread: http://forums.tccoa.com/showthread.php?t=123897

It's not fun to do with the engine in the car.
 

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Discussion Starter #3
thanks for the reply. i am confident that the intake side of the egr system is clear of carbon now. the egr valve itself and what ever is between it and the exhaust is still suspect.

cleaning the egr passages in the intake were really not all that hard in my opinion. i don't think it took more than an hour and a half each time i did it. if i need to change or remove the egr valve itself, that looks like it will be a totally different story.
 

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could also be the dpfe sensor or the egr vacuum regulator solenoid
i suppose that very well could also be a problem but i am thinking if the engine should really "almost stall" when vacuum is put to the egr valve and mine just slows down a bit, something is wrong with the valve itself or what ever is between it and the exhaust (i can barely see the top of the valve, much less what is underneath it).
 

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There is a short tube connecting the EGR valve to the exhaust manifold. It is very possible that the orifice in this tube is plugged with carbon, in which case a fully open and unrestricted EGR valve would hardly have any exhaust passing through it. The tube is the real PITA to remove.
 

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There is a short tube connecting the EGR valve to the exhaust manifold. It is very possible that the orifice in this tube is plugged with carbon, in which case a fully open and unrestricted EGR valve would hardly have any exhaust passing through it. The tube is the real PITA to remove.
that makes sense. the egr is not terribly expensive. not that i just want to throw parts at it but i am wondering if i should just change it at the same time as cleaning the tube. it sounds like the work will almost be done with the tube off. i'd hate to have to take it all apart again if it still doesn't work when reassembled.
 
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