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Greeting’s all I got a 2001 Dodge Ram 1500. It now has about 164k miles on her. Its the 5.9l gas v8, 4×4, auto trans. I acquired her this past summer. Love my truck despite her little issues. I do have one thats throwing me a bit tho. I’ve noticed on long drives that put me on the interstate (more than an hour drive time out) if Im climbing a steady hill (such as the ones on I-71 by Ashland or proceeding north of there) I’ll get what feels like a misfire. It only occurs on a hill with a steady but long duration grade if that makes sense. If Im holding normal speed and about 2k RPM I’ll get a vibration it almost feels like Im going over a rough road at first and then I feel a slight bucking sensation and hear a bit of a popping or a back fire. If I shut off cruise and completely come off the gas the misfire goes away. Sometimes if I shut off cruise and go to WOT it’ll go away too but not all the time. When all of this is going on I’ve seen the check engine light flash (misfire code) the last time it did this when I got it home there were no codes in the computer. I guess the condition wasn’t going on long enough for the computer to confirm the code.
This problem has only come up if I’m on longer than normal trips specificly going on the hills at interstate speeds. I dont do these trips too often. And the truck never does this on my daily or weekly trips although it should be noted my daily/weekly trips are much shorter and with no interstate travel.
I was wondering if y’all might have any suggestions.
In recent months I’ve done a tune up on the truck (wire’s, plugs), bleed the cooling system, oil change back at 160k and my owner’s manual says Im good till 167500, and a transmisssion fluid change at about 163k. The power steering pump had to be replaced recently and it was only after this that the issue first arose although I dont recall very long trips with the truck before the power steering pump change.
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The nattery is a year old and recently had it tested it came out fine. I’ll get a spark tester this week and get back to y’all with what I find. Appreciate the help
When you last changed the plugs what was their condition ? any oil fouling ? remove the air cleaner housing and open the throttle body plate and with a good flashlight look down into the intake manifold. if you see oil pooling in the lower area of the intake then you have a blown lower plenum plate gasket ( will be surprised if there is no oil ) this is a very common prob with second gen rams. when this happens oil is pulled into the intake and then into the cyls were it is burned which can cause a misfire. this will not set a code. also on the second gen rams the ecm/pcms tend to fail ( another common prob ) will start as intermittent missing then progress to stalling and shutting off. I would start with the lower plenum inspection first.
Be sure # 5 and # 7 spark plug wires are not running parallel and touching each other. Because those two cylinders fire one after the other in the firing order the wires can actually induction fire between the two and cause a misfire and lack of power under certain conditions.
If you didn’t replace the cap and rotor it might be a good idea.
Thx all. I plan to do the spark test and check for oil on Friday I think. My wires are pretty well placed apart but I’ll watch for that too
Well something interesting happened today. The check engine light came on P0308 is set in the computer. I nitially tried a power balence test on the ignition side there was very little if any drop at all between me pulling plugs. I havnt tried the fuel injectors yet,I did buy a spark plug tester. (the kind you adjust for the gap for your car) I set it to .4 for my truck and tested cyl 7 as a control so to speak. I found 7 was showing no spark at all. I wound it down and got an intermitten spark at ,35 or so and a good normal spark at .3 Cyl 8 was the same although it seemed to “skip” like spark spark spark spark skip spark skip skip[ spark but not consitantly. I havnt trested the spark anywhere above idle tho I should. Im also going to try a voltage leak test too here shortly
This is what I was referring too.
You can also normally use a test light
http://www.harborfreight.com/circuit-tester-30779.html
The spark gap for your vehicle should be .040 inches according to everything I have seen and read.
I see where its been suggested but do not see, unless I overlooked it, where you have not replaced or at least taken the distributor cap off and inspected the inside for cracks, burned contacts, carbon tracks and the rotor for being burned on the contact and worn out.
I replaced the cap and button the button seemed to be melted/worn according to my buddy that was helping. The truck doesnt feel like it’s missing now and the computer hasnt set a misfire code as of yet. I noticed my oil seemed a little low today and topped it off. My buddy noted some carbon and a little bit of oil on the walls of the intake by the butterfly flappers
Another update. So far the misfire code has not resurfaced. We were running short on time so we only did a compression test on cyls 8 and 3. Both had 160 psi. We checked the spark plugs on Cyls 3 and 8 and both showed normal discoloration but 8 appeared to have a melted tip and showed some signs of oil burn. Not sure where the oil would be coming from if the compression is good
You said you did compression test did you do it wet and dry.? Because you really need too. It might have good compression wet but,when dry have worn out rings letting oil come by. Brings me memories of a truck that was worked on by 7 mechanics and not fixed for over 8 months all because the manufacturer said that it could not be this and we are not allowed to test for it.
Worn valve guide can do it also. Worn valve stem seal can do it also and normally denotes the former. The melted tip makes me think something is off with that and if you had a worn exhaust valve guide it would not seat all the way letting excess heat in from the exhaust. Easiest way to test for this would be a leak down test.
[quote=”MDK22″ post=125506]You said you did compression test did you do it wet and dry.? Because you really need too. It might have good compression wet but,when dry have worn out rings letting oil come by. Brings me memories of a truck that was worked on by 7 mechanics and not fixed for over 8 months all because the manufacturer said that it could not be this and we are not allowed to test for it.
Worn valve guide can do it also. Worn valve stem seal can do it also and normally denotes the former. The melted tip makes me think something is off with that and if you had a worn exhaust valve guide it would not seat all the way letting excess heat in from the exhaust. Easiest way to test for this would be a leak down test.[/quote] ^this. Always do a dry test first and write down all the numbers to compare to a wet test. If the wet test comes back with higher numbers, the rings are worn. If both tests are similar it’s most likely the valves. Two adjacent cylinder low=look at the headgasket.
To be honest i forget what type of test I did pretty sure it was dry tho. Disabled the fuel pump and cranked the engine although strangely it seemed to be getting fuel cause it was getting some combustion while cranking
[quote=”ChrisR1987″ post=125514]To be honest i forget what type of test I did pretty sure it was dry tho. Disabled the fuel pump and cranked the engine although strangely it seemed to be getting fuel cause it was getting some combustion while cranking[/quote] With a compression test you want to disable both spark and fuel and block open the throttle. You may want to redo the test. Fuel during a compression test can cause cylinder wash lowering compression and inaccurate results.
Yeah we realized our mistake when we went to do cyl 3. We disabled both spark and fuel but didnt block open the throttle. Cyl 3 showed 160 as well. I will see about getting my buddy with the tool so i can redo the test next week
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