Posted: 12/12/2007 9:14:22 AM EDT
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I thought I'd ask here before I bring it in. This truck will just barely stay running when first started cold. I replaced the cap and rotor, which were worn some , but I've run worse. No help. It runs good when warmed up, maybe just a little chugging when towing. I checked the alternator output , when cold (rough, slow idle) it only puts out 11+ volts, but when warmed up it puts out a healthy 14 at idle. It's ben a good truck and just started doing this recently. 154K on it now. I don't want ot just start throwing parts at it. Any ideas? |
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IS it multi port fuel injected or throttle body. Could be bad injectors, etc. B4 it started running bad, was anyone monkeying around under the hood. a simple wire or sensor can play havock on vehicles. The alternator output is something odd as well. As soon as you start the truck it should be 14.6 volts give or take. IT shouldnt be low when cold. The only thing could be youve got some kind of electrical draw and its running battery down. Newer vehicles need a good battery to keep running. Its not like the old days where vehicles could run on alternator alone. May want to check into that and any other electrical issues. You could have compounded issues or could be all related. Jus keep checking the simple stuff first. Think about what your vehicle is doing or not doing and try and understand what makes it do that or doesnt do that. etc. |
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multiport injected. Nothing was messed with under the hood when it started acting up. I don't know if it's getting progressively worse or if the short trips it's been used for aren't enough to keep the batt. up. My teenage Daughter has been driving it a mile to school and back. I thought the low alt. output was caused by the very low rpm when it was struggling to stay running. No? The newer vehicles are very frustrating for me. I've rebuilt engines, one auto tranny, several harleys, and other bikes, but all this electronic crap on them now days just drives me nuts. Thanks for the help, any more ideas? |
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If you had not mentioned the low alt. output, I would check certain things, but to me that is the key right now and could be simple fixes. Here is a couple suggestions. 1) Get on the interstate and put 20miles of straight above 2000rpm driving. 2) With everything off and no doors open, take a voltage reading on your battery with the truck off. Record this number. It should be 12.8 or so. Believe it or not and ive gotten into this with many ppl, but 12 volts is not 12 volts. A good battery should be 12.8 - 12.75, if a battery is 50% dead, itll read around 12.3-12.25 volts, while this is still 12volts, there is a diff. Now. I would take a reading right away, and then in a hour check the reading again, if it goes down, then youve got a draw on the system, if this is the cause I can explain how to find that later on. It may not be necessary right now, so no reason to get into it. THe other idea is to take it to the auto parts store to have them check the alt out put, and the battery. To get a good test of the battery it usually needs to done overnite, they slow charge it, if itll take a complete charge and then put a load on it. Something else to check. If you have the truck running, becareful, but test with a volt meter the output right at the back of the alternator and then at the battery itself. Could have a bad ground or loose connections. That is another thing, but would show itself all the time is corroded and loose battery cables. But I would check this simple stuff first b4 spending any money or taking it anywhere else. With what you told me, I would focus on those issues, b4 looking at any real mechanical issues. vehicles need a good electrical and charging system to run, tis that simple. I would really look at the battery and alt. You said you checked it, but how did you check it? Dont rely on factory gauges and you need to check it right at the alternator, but be very careful you could fry shit if you short it out or touch the casing of the alternator will touching the output of it. |
Id check it at the alt itself. Also when was the last time the belt was changed or adjusted? You could have glazed the pulleys and or the belt could be shot, when it warms up the belt expands and "catches" better, also check to see if the alt pulley isnt loose. This could be a long shot, but it would simple things to check. Like you, Im about doing it myself and try to approach things in the simplest possible way so I dont feel over welmed. |
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Have a shop put a real scanner on it, not some junk code reader at Autozone. That way they can look at codes and the data of how the engine runs. On a wide assed guess sounds like a stuck open T'stat or a coolant temp sensor not changing resistence. Have a shop check it out, not a dumb assed clerk. When I'm sick I go to a doctor not the clerk at Wal-mart to find out what is wrong with me. |
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I assume you have a 5.0/5.8? Does it have a rough idle and want to die? Try unbolting the IAC (should be two 8mm bolts and a electrical plug) and cleaning it out with carb cleaner. It should be bolted to the throttle body. You can also take the Mass air filter off, and clean it out with carb cleaner (mainly the sensor that is poking out in the middle of it with two wires, they sometimes get grimy). IM me and I will try to help you more, I dont look in this section again. |