ECT and lean code 172?
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ECT and lean code 172?
I have scanned this site and none of the problems within seem to match mine identically, but I am learning a ton about my F150.
Here is my problem, when cold, everything runs well, as soon as I reach operating temperature, it starts running lean and I sometimes get a 172 code to reinforce this. All I have to do is pull over, turn the engine off then restart and she runs fine. I am leaning on an engine coolant temparature sensor. It doesn't do it every time, very sporadic but it is predictable by watching the temp guage.
What doesn't make sense is if it was the ect, wouldn't it run rich versus lean. Maybe I'm wrong in my logic and just confused how this ect works. Any education and other opinions on what is wrong would be appreciated.
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
Here is my problem, when cold, everything runs well, as soon as I reach operating temperature, it starts running lean and I sometimes get a 172 code to reinforce this. All I have to do is pull over, turn the engine off then restart and she runs fine. I am leaning on an engine coolant temparature sensor. It doesn't do it every time, very sporadic but it is predictable by watching the temp guage.
What doesn't make sense is if it was the ect, wouldn't it run rich versus lean. Maybe I'm wrong in my logic and just confused how this ect works. Any education and other opinions on what is wrong would be appreciated.
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
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ECT and lean code 172?
GCKK try doing this. I ran into a similar problem in which my truck was running a little on the lean side. Disconnect your battery cables. Come back in say 30 to 45 minutes and reconnect your battery. This should reset your stock computer. Now try driving around for a while and see what happens. If so then I agree with you the engine coolant temperature sensor could be faulty. Grab a Chilton's manual(a very good book to have) and see what it says about testing the sensor. Good luck!
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ECT and lean code 172?
Karl ,
Another way to test the sensor is to measure its resistance cold , start and run the engine until it reaches operating temp . Running the engine with the connector disconnected will set a code for it , but it ignore it until you verify the resistance for the ECT is within specs . This time of yr the cold coolant will be in the 68 , 70 deg range , its resistance at that temp should be in the 37 Ohms range . At O/T it should be in the 2 to 3 Ohmn range . As the coolant warms you should see the resistance decrease . If you find its out of spec , replace it . Clear the codes and road test .
Paul
Another way to test the sensor is to measure its resistance cold , start and run the engine until it reaches operating temp . Running the engine with the connector disconnected will set a code for it , but it ignore it until you verify the resistance for the ECT is within specs . This time of yr the cold coolant will be in the 68 , 70 deg range , its resistance at that temp should be in the 37 Ohms range . At O/T it should be in the 2 to 3 Ohmn range . As the coolant warms you should see the resistance decrease . If you find its out of spec , replace it . Clear the codes and road test .
Paul
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ECT and lean code 172?
Ran the test this morning, 37.5 Ohms cold and gradual decrease to 3 Ohms on OT. Like I said ealier this is sporadic and happens every third or fourth day. I have had it occur twice in one day, but that has ben rare. Is it possible for this sensor to have an intermitent failure or should it fail completely?
So I still have the one question, Logically, wouldn't the engine run rich versus lean if the ECT was defective? I'm a little ignorant on what the function of the ECT is, but my assumption is that it is like the choke on a carbuerator.
Appreciate the input so far and I beleive I have just about licked most of my problems from this site.
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
So I still have the one question, Logically, wouldn't the engine run rich versus lean if the ECT was defective? I'm a little ignorant on what the function of the ECT is, but my assumption is that it is like the choke on a carbuerator.
Appreciate the input so far and I beleive I have just about licked most of my problems from this site.
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
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ECT and lean code 172?
Yes if an engine runs at a cooler temperature it should run in a richer condition. Your logic is correct. If worse comes to worse you can always get another etc from an autorecycler instead of going to a place like Autozone or Checker's. Of course this is just a cheaper shotgun affect at solving the problem. The etc could be failing and on its way to complete failure. I would replace it before this happens. If you don't this could lead to other more serious problems. A good creed to live by is: If a part starts to show wear or signs of failure, replace it. All of these some 10000 parts affect each other someway and somehow. If one fails it puts unnecessary stress of the others!!!
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ECT and lean code 172?
It is not the cost that is hindering my decision, $12.99 at autozone, it is just that the part in question does not fit the symptoms if I understand its operation. That is why I'm confused. If not the ect, what other speculative guess would you have to cause the engine to go lean at operating temp? I have thought about the fuel pump/filter, but the problem is not consistent enough for that. And considering I can get back to normal by just stopping and turning the ignition off then back on leads me to a switch or sensor. This is surely a little problem and I have gleaned over all the F150 sites and have not found a duplicate on it. Be kinda cool for the old data banks.
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
Karl Knox 95 F150XL 2WD Ext Cab 4.9L I6 EFI E40D
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From: Yeppoon Queensland Austr
ECT and lean code 172?
G'day from Oz. Sometimes it helps to remove the E.C.T.sensor and clean off any build up of residue from the coolant.gp
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ECT and lean code 172?
Is a 172 code engine coolant out of range. I don't have those books in the house. Don't guess on these codes find out what they are and follow that diagnostic path. If the component(s) pass these test then start looking at wiring/vaccume problems. You can spend a lot of money replacing good parts and not fix the problem.
