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jlwelding

Black Cloud Over my Head

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I have a Question which one controls the idle ECM or VP44. And yes I am still fighting my self weather to buy a vp44 or not.Some of you know what is going on with my truck,it is such a night mare I dont even wont to go there.But anyway here goes, rpm drop hard when shifting and even harder when AC is on. It drops so hard and fast that when AC is on and you kick it in nuteral coming to stop sign it will almost die.

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I think its the ECM that controls the idle more so... Basically the ECM watches the Crankshaft sensor or Camshaft sensor for speed (RPM) and then dictates if the governor should put more fuel to it or not to keep idle up.Now I know that the VP44 can run without a ECM present but it does require a special Cummins box to feed a signal to the VP44. There is 2 modes of operation on the box idle and high idle. that's it...When I got time later I'll dig up the wiring diagram of the VP44 and you can see the input it takes... ;)

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Ok I talked to dealer they dont know nothing, as you can guess if it dont have a part # they dont know how to do anything.I talked to Dodge mechanic and he said he would install with out flash because the up dates would not let it flash with 01 numbers. We are installing 02 ecm in a 01. I am thinking it is a waste of time :confused: I am just going to go buy a emc put it in if that dont fix it vp44,if that dont fix it part it out.

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I don't know what you have into it or how many miles but parting it out seems extreme! Is there a Cummins shop besides the Dodge dealer? Cummins has their own dealer network. Russ

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Huge losses in power and erratic ilde on a VP44 equipped truck usually means that you have isses that are not ECM related.Have you checked the fuel pressure at all on this truck?,I have seen many trucks do what your describing and it usually ends up with a lift pump and VP44 pump failure due to low fuel pressure.See if the lift pump fails or is weak the VP44 will still draw fuel as long as the system has no air leaking into it.This causes low power syndrome,hard starts,low idle,erattic performance.IF the truck is driven a long time like that you will usually end up with a VP44 that fails.You should have the truck checked for codes and let us know what you pull off the truck....Andy

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Everything checks out good fuel pressure is 13psi 12 at wot. You cant find codes there is nothing even with scanner. I think I will throw a ecm at it, for the cost to take it to a shop and them to tell me it's a ecm. Ecm controls the high idle and low idle the best I can find. Until somebody comes up with a idea better than that I think it makes the best sence. Vp 44 gets info from ecm then process.

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I have a Question which one controls the idle ECM or VP44. And yes I am still fighting my self weather to buy a vp44 or not.Some of you know what is going on with my truck,it is such a night mare I dont even wont to go there.But anyway here goes, rpm drop hard when shifting and even harder when AC is on. It drops so hard and fast that when AC is on and you kick it in nuteral coming to stop sign it will almost die.

A friend came up with this, is it possible that the waste gate is staying closed or almost closed causing the rpm to drop like that? A nd how do I go about checking this?

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Assuming that you have a manual transmission, the wastegate should close during shifting. The reason being that when you release the throttle and push in the clutch the load is taken off the engine. Therefore the exhaust gas temperature plummets causing lower drive pressure for the turbine. If the wastegate was sticking closed during driving it would cause an overboost condition most likely.Just a thought, have you checked the crankshaft position sensor and camshaft position sensor?

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It has new cam shaft sensor and the crank sensor is built in the vp44. You hit the nail on the head when you said the gate closes when you shift.The rpm drop like a rock between shifts. When you pull up to stop sign it will almost die when ac is on.So if I pluged waste gate to test run you think the rpm will stay high?

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sensor is new and putting out .671 this is as low as it will go.Tim says this is good.

Yeah that the rheostat part how about the the 2 idle validation switches???

Posted Image

Pins 6, 2, 1... On the stock side of the adapter?

Idle switch control several different functions... (Exhaust brake, Idle functions, high idle, etc)

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John at Holland Court Diesel is going to send me a used ECM off a 01. :thumbsup If it works pay me when you can if not send it back. Man, there are still some real folks out there. ;)

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