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Engine rpm's still surging up & down at idle, replaced vp again..help!!


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O.K I replaced V.P 2-months ago, after this the engine idled up & down spuraticaly. then i noticed it would try to die sometimes when shifting to drive or reverse.. Yesterday i changed out the VP again & problem is still the same and still there... last nite after idleing for 1/2 hour the RPM'S would roll up 2-300rpm at a time this is worse than before:banghead: Is this ECM???:shrug: PLESE HELP!!:pray: Richie

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My 2001 does this too. It started about 3 months ago. My LP fuel pressure is fine, but I have a rough idle and with very light throttle pressure it sounds like a heavily cammed engine with a big lope. It surges at slow speed/light throttle like creeping out my gravel driveway, but once I'm on it everything is fine. It does surge when coasting to a stop but I have an auto trans. I have no idea what it is but am just waiting for the VP to die I guess.

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Correct me if im wrong but I do believe you guys are both 24 valves with auto not to be preachy or nething but its simple if you've got good pressure to the vp your lift is good I dont know a way to test the vp44 directly other than live feeds an error codes so say that is good then its one of five basic things computer, wiring, cam, crank and apps sensor the apps sensor went on my truck and it was failing for six months untill it went completly belly up I could drive it but I had no error code untill it went completly south of the border it would surge die and do all sorts of goofy things no I have also replaced my crank sensor this on my truck seemed rather touchy I had an error code before it went bad and didnt go away till I put a new one in and cleaned the connection then cleared it now wenever I clean my truck if I get water down by that sensor its the only one that would trow a code clear let it dry and it'd be gone so no error codes I would look for loose connections try to get someone to get you live field unless you can do it yourself then check apps and cam sensor if i was close to you I'd bet you a beer that surging and unexplained stuff in a computer cotroled truck is computer related wether it be one of those five things and anyone could be bad and the truck may still drive just a thought and my :2cents: hope it helps and I cant guarantee nething it but its a good place to start

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Just my two cents, my 2000 3500 did this too. Never any codes. I had the 2000 looked at at several dealers and they did several things in attempt to fix, new fuel distributor, new cam sensor, and new battery cable ends and ironically the battery cable ends seemed to solve this on my 2000 for several months before I wrapped it around a pole. My 2001 3500 has done this from day one and 18.7 miles, and the battery cables ends are tight on the batteries so I've never done anything, wasn't interested in not having the truck during trial and error repair and am out of warranty of course. I've seen several references to this type of behavior being a lock out torque converter issue functioning at idle, or doing the same thing at crusing speeds like 70mph. Try turning off the overdrive when your at idle if it bothers you so much, I think that shuts off the TC circuit, but I don't know jack. Never really bothered me that much, actually only really notice it surging when I'm in line at a drive-thru restaurant right next to the building and hear it, and sometimes I can see the dash and head lights kindof getting brighter when it upsurges at night which begs the foil over the alternator wire ends question. Good luck and keep us posted!!! I'd love to hear a definitive solution. Dave

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Go to You Tube and type in JL Welding truck and if this is what your truck is doing all I can say is wellcome to my world. I have done the test this test that dont throw your money away and all the such. Ask Mike what he thinks about it.I have spent 4k trying to track it down and I dont wont to hear have you checked your grounds? The bolts are worn out from cleaning. What I can tell you is everything that touches the outside of the eng. is brand new at least one time some two and three times. I am trying a used wiring harness in a few days when it gets here. If that dont fix it nothing will. I am even willing to make a bet with anyone here that dont fix it either.I have had so many people look at this truck when they see me coming they hide. When you call, you get answer machine.What I would like to do is do like the computer hunting thing they had a few years ago where you shot from your computer, only have my truck on there with a pay out if you hit the right spot the truck blows to H and back. Now that would be cool. Can you amagin how many people would watch that. Oh and use a 50 cal lolIf anybody out there would like to do this I will donate my truck.lmao

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i've been following your "events" for awhile, jl. and when you started down the harness path, it made me wonder....in the cable industry, when we are looking for a bad spot in the line(possibly 100s or 1000s of feet) we use a TDR. the TDR sends a RF wave down the copper. the TDR then tells of any impedance on that line, and how many feet away that is. could something like this be used to test an engine's harness?

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O.K sorry Guys, Many thanks for the replys... I have been gone for a few days and have nor been able to reply to the thread....I think i need to better explain what my truck is doing ....here goes;

When i start my truck, say like now..it idles O.K. then after it idles for a while it will start idleing up on its Own just like theres a Ghost in the cab patting the fuel pedal... uuuup & doown..at random

:wtf:

also if you when you put in reverse and forward it eithier tries to die or does die..especialt if yo pat the fuel pedal reving up the engine and the shifting after the rpms fall back it dies every time

sence my last post..Talking several times with Michael, I have completey took apart my entire ground system & checked...checked the Ground wires {black/tan} from VP & ECM TO Battery Ground with DVM, all were good with little to no resistance.. "OH Yeah" we found out something interesting about the "ECM GROUND" Buuut..I let Michael explain that.."Dont want to spoil it for him" ha..ha..

I replaced the cam sensor..no change...my truck does not have crank sensor 2002 model

I am at the point that i think it has to bee the apps or ECM which one?....i don't know:shrug:

Richie

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  • Owner

ECM is going be the next step... :rolleyes: As for Rburks comment...

"OH Yeah" we found out something interesting about the "ECM GROUND" Buuut..I let Michael explain that.."Dont want to spoil it for him" ha..ha..

As he calls me out on a mistake... Well being the first wiring diagram we all had was the cheap black and white diagrams from the Dodge FSM well I did pay close attention to the grounds. Come to find out the color map shows very clearly the ground terimnal behind the starter is lift pump, fuel heater and I think grid heater solenoid. As for the rest of the grounds like the engine sensors and the ECM ground we start tracing them down and found out they come together at the engine side battery ground not the terminal behind the starter. :sofa: So I need a good ol'.... :punish:
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Go to You Tube and type in JL Welding truck and if this is what your truck is doing all I can say is wellcome to my world. I have done the test this test that dont throw your money away and all the such. Ask Mike what he thinks about it. I have spent 4k trying to track it down and I dont wont to hear have you checked your grounds? The bolts are worn out from cleaning. What I can tell you is everything that touches the outside of the eng. is brand new at least one time some two and three times. I am trying a used wiring harness in a few days when it gets here. If that dont fix it nothing will. I am even willing to make a bet with anyone here that dont fix it either. I have had so many people look at this truck when they see me coming they hide. When you call, you get answer machine. What I would like to do is do like the computer hunting thing they had a few years ago where you shot from your computer, only have my truck on there with a pay out if you hit the right spot the truck blows to H and back. Now that would be cool. Can you amagin how many people would watch that. Oh and use a 50 cal lol If anybody out there would like to do this I will donate my truck.lmao

Im sure you have checked but I changed injectors one time and forgot to pull one of the tubes out and got an idle that sounded alot like that. I knew what it was because I knew I messed up when I did it. :2cents:
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Im sure you have checked but I changed injectors one time and forgot to pull one of the tubes out and got an idle that sounded alot like that. I knew what it was because I knew I messed up when I did it. :2cents:

How did you get the Injectors out without pulling the Tubes first?????:shrug:

--- Update to the previous post...

As he calls me out on a mistake... Well being the first wiring diagram we all had was the cheap black and white diagrams from the Dodge FSM well I did pay close attention to the grounds. Come to find out the color map shows very clearly the ground terimnal behind the starter is lift pump, fuel heater and I think grid heater solenoid.

As for the rest of the grounds like the engine sensors and the ECM ground we start tracing them down and found out they come together at the engine side battery ground not the terminal behind the starter. :sofa:

So I need a good ol'.... :punish:

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