fords4life Posted September 5, 2018 Share Posted September 5, 2018 So on to the next problem..... Truck is running rough and has a lack of power, especially down low. Once up to speed, it holds speed ok and is smoother, but not perfect. KOEO I'm pulling codes 18 and 31. KOER I'm pulling a 44. I tested the EVP sensor and it tested within range(voltage and resistance), but having the 31 and it being 32 years old, I'm guessing I should just replace it. As for the 44, I just replaced the air pump so that's not it, but could be the diverter valve and if 31 is an issue, from what I've seen, it could be causing the 44 as well. Either of the two could also be vacuum leaks and/or vacuum solenoid issues from what I've seen. Anyone have experience with these two and thoughts on where to start? Link to comment Share on other sites More sharing options...
vjsimone Posted September 5, 2018 Share Posted September 5, 2018 Ref Code 44, the Self-Test is only testing the electrical operation of the TAD or TAB Solenoid. So, I would check for supply power, 12vdc to the connector. Unplug the connectors and measure the resistance on those 2 solenoid coils and compare the readings. As far as I can remember with the KOER 44 Code, the ECA is checking to see that power is applied to the TAD/TAB Valve Solenoids when the ECA expects them to operate. But, would like to verify. Link to comment Share on other sites More sharing options...
vjsimone Posted September 5, 2018 Share Posted September 5, 2018 As far as the Code 31, dead spots on the potentiometer can cause this fault. If you replace it, sometimes the replacement shaft length is longer or shorter and may produce a different fault code. You may have to remove or add length to the shaft. Verify source voltage and ground path as well. Link to comment Share on other sites More sharing options...
vjsimone Posted September 6, 2018 Share Posted September 6, 2018 Are you getting a rich smell out of the tail pipe ? Link to comment Share on other sites More sharing options...
fords4life Posted September 6, 2018 Author Share Posted September 6, 2018 Are you getting a rich smell out of the tail pipe ? Yes. It has always been slightly rich, but certainly seems richer after starting to "miss". It does have a new O2 sensor pre-cat. But is also running the factory original cat which I'm sure is worn out, although it did pass emissions. Thank you for the other info. I might have time before I leave for my hunting trip to check the solenoids. As far as the Code 31, dead spots on the potentiometer can cause this fault. If you replace it, sometimes the replacement shaft length is longer or shorter and may produce a different fault code. You may have to remove or add length to the shaft. Verify source voltage and ground path as well. I did verify source voltage at 5.04v with a digital meter, but did not confirm path to ground. Link to comment Share on other sites More sharing options...
fords4life Posted September 29, 2018 Author Share Posted September 29, 2018 Are you getting a rich smell out of the tail pipe ? Yes. It has always been slightly rich, but certainly seems richer after starting to "miss". It does have a new O2 sensor pre-cat. But is also running the factory original cat which I'm sure is worn out, although it did pass emissions. Thank you for the other info. I might have time before I leave for my hunting trip to check the solenoids. As far as the Code 31, dead spots on the potentiometer can cause this fault. If you replace it, sometimes the replacement shaft length is longer or shorter and may produce a different fault code. You may have to remove or add length to the shaft. Verify source voltage and ground path as well. I did verify source voltage at 5.04v with a digital meter, but did not confirm path to ground. I knew I should have logged on before I wrapped up for the night. I forgot check resistance on the solenoids. I did put a piece of aluminum between the EGR and the manifold and the truck no longer feels like it is missing, but it is still running really rich. I did confirm voltage to the solenoids. Pulling the vacuum line off of the EGR valve, I think I can feel vacuum on the line, but it isn't very strong. I'm also wondering if a lack of vacuum is what is causing my soft brake pedal and brake light? Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 29, 2018 Share Posted September 29, 2018 I knew I should have logged on before I wrapped up for the night. I forgot check resistance on the solenoids. I did put a piece of aluminum between the EGR and the manifold and the truck no longer feels like it is missing, but it is still running really rich. I did confirm voltage to the solenoids. Pulling the vacuum line off of the EGR valve, I think I can feel vacuum on the line, but it isn't very strong. I'm also wondering if a lack of vacuum is what is causing my soft brake pedal and brake light? I don't want to sidetrack things, but Vinny may be riding today so I'll ask: How much manifold vacuum do you have at idle? Link to comment Share on other sites More sharing options...
fords4life Posted September 29, 2018 Author Share Posted September 29, 2018 I don't want to sidetrack things, but Vinny may be riding today so I'll ask: How much manifold vacuum do you have at idle? I asked myself that question last night. Making a run to the junkyard this morning and then we'll get a vacuum gauge so I can check that. Link to comment Share on other sites More sharing options...
fords4life Posted September 29, 2018 Author Share Posted September 29, 2018 I asked myself that question last night. Making a run to the junkyard this morning and then we'll get a vacuum gauge so I can check that. 16" vacuum at idle. Link to comment Share on other sites More sharing options...
Gary Lewis Posted September 29, 2018 Share Posted September 29, 2018 16" vacuum at idle. That's not very much. Oh wait, where are you located? If up around 5000' it isn't too bad. Link to comment Share on other sites More sharing options...
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