Strange high idle?

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bigred2004

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Dec 14, 2009
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Anybody know if a '99 automatic would have some type of factory flash causing it to idle around 1300 until it warms up? This is the only bug with this truck that is driving me insane. When you first crank the truck cold it will idle normal unless you free rev it anywhere about 1200-1300rpms then it'll drop back down and stay at 1300 until you drop it into gear and put a load on it then it drops back down to ~800 where it should be. The strangest part is even once it warms up it'll still do it but if the truck is up to operating temperature and I kill it, then crank it back up it won't do it anymore. Once it sits and cools back down it'll start all over. I was thinking bad sending unit or something at first but everything works and runs perfect, and it doesnt hang up once you kill it and restart it. Im thinking maybe the dealer can re-flash the computer and get rid of it?
 
If I remember reading correctly, when trying to diagnose a bad VP44, the dealership did have a flash that allowed the truck to high idle to 1200-1300 RPMs when the truck is cold or has been sitting idling for a period of time.

I could be wrong. Just saw it under one the 'searches' I did.
 
Yes thats a update.Was the ecm reflashed? It has to be 39* if i remember correct.
 
Man I have searched everywhere and couldnt find anything. The guy I bought the truck from has zero knowledge about the mechanics of these motors. From what I know the truck is 100% stock so maybe ill talk to the dealership and see if they have a reflash available?
 
bigred2004 said:
Anybody know if a '99 automatic would have some type of factory flash causing it to idle around 1300 until it warms up? This is the only bug with this truck that is driving me insane. When you first crank the truck cold it will idle normal unless you free rev it anywhere about 1200-1300rpms then it'll drop back down and stay at 1300 until you drop it into gear and put a load on it then it drops back down to ~800 where it should be. The strangest part is even once it warms up it'll still do it but if the truck is up to operating temperature and I kill it, then crank it back up it won't do it anymore. Once it sits and cools back down it'll start all over. I was thinking bad sending unit or something at first but everything works and runs perfect, and it doesnt hang up once you kill it and restart it. Im thinking maybe the dealer can re-flash the computer and get rid of it?
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Your IAT sensor is lying to the ecm by telling it that it's colder than it really is. It wouldn't hurt replacing it just to see if it works; they're not expensive.
 
I planned on replacing the APPS just because of the mileage of the truck. First once I get done with the cosmetics on the truck im going to take it by the dealer and reflash the computer to start with.
 
Id start by cleaning and greasing grounds before I spent any money. I was having a high idle coming off the freeway and dead pedal. I check the gray connector coming off the battery and found .17 volts of resistance there. Cleaned it and put it back together and ALL my strange problems went away. I hate mindlessly throwing money around for parts hoping for a cure. Good luck.
 
Well luckily I dont have any bad connections on the batteries. I just replaced all the terminals. So ill start hunting down the problem. Sounds too consistent to be a wiring issue though.
 
bigred2004 said:
Well luckily I dont have any bad connections on the batteries. I just replaced all the terminals. So ill start hunting down the problem. Sounds too consistent to be a wiring issue though.
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:doh: I wasnt sayin the terminals. I was saying the ground connectors coming off the battery. Too consistent to be a wiring issue? I guess if corrosion comes and goes. :blahblah1:
 
HOGS2500 said:
:doh: I wasnt sayin the terminals. I was saying the ground connectors coming off the battery. Too consistent to be a wiring issue? I guess if corrosion comes and goes. :blahblah1:
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Dang! bif Down boy! Down!
 
Sounds like a high idle flash except for the part where you said you have to touch the throttle manually:

Date: September 3, 2001

Models: 1998 1/2-2002 BR/BE Ram Trucks

NOTE: THIS BULLETIN APPLIES TO ALL RAM TRUCKS BUILT AFTER DECEMBER 17,1997 AND EQUIPPED WITH THE 24-VALVE 5.9L CUMMINS DIESEL ENGINE.

Discussion:

This bulletin involves selectively erasing and reprogramming the Engine Control Module (ECM) with new software (Cal 55Tl8, 57Tl1, 56Tl3, 59T7b, and 59T8b.)

Symptom/Condition:

Extended idle operation, especially in cold weather, can lead to stuck valves and bent push-tubes due to insufficient cylinder heat. This allows varnishes/oils to condense on the exhaust valve stems, leading to stuck valves, and damaged valve train components. A new software feature, enabled or disabled through the DRB III (See instructions under Repair Procedure), reduces the chance of valve sticking and improves cab heat warm-up time.

Once enabled, idle speed will slowly ramp up from 800 rpm to 1200 rpm when all of the following conditions are met:

1. Intake Manifold Temperature less than 0°C (32°F) and,
2. Coolant Temp is less than 60°C (140°F) and,
3. The Transmission is in Neutral or Park and,
4. The Service Brake pedal is not depressed and,
5. Throttle = 0% and,
6. Vehicle Speed = 0 mph

Additionally, if Intake Manifold Temperature (IMT) is less than -9°C (15°F), and all of the parameters above are met, three of the cylinders will be shut off upon reaching 1200 rpm, creating a slight change in engine sound which is normal. This allows the engine to create increased heat in the cooling system, allowing more rapid engine warm up and cab heating.

Both features will automatically disable when one of the following occurs:

1. The Automatic Transmission is placed in gear (forward or reverse) or,
2. The Service Brake pedal is depressed or,
3. Throttle position is greater than 0% or,
4. Vehicle Speed is greater than 0 mph or,
5. Coolant Temperature is greater than 79°C (175°F).

Engine speed will return to normal operation at 800 rpm. If the engine continues to idle and coolant temperature is at or below 60°C (140°'F), the feature will re enable. In order to operate properly, the Accelerator Pedal Position Sensor (APPS) must stay at idle.

NOTE: ANY TYPE OF AFTERMARKET IDLE SPEED KICKER THAT ACTIVATES THE APPS WILL DISABLE THIS FEATURE.

Use of the 110V block heater will not allow the feature to function after an overnight soak. If the vehicle is left idling, without use of the block heater, 1200 rpm operation will begin when the intake temperature drops below O°C (32°F) and coolant is less than 60°C (140°F).
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There is a mod people do with a switch that does the same thing:

http://mopar.mopar1973man.com/cummins/2ndgen24v/high-idle/high-idle2.htm
 
Yea the rpms don't raise on their own which is weird but it holds that consistent ~1200rpms but it only disables it when I drop it into gear. Thats the confusing part. Depressing the brakes wont change anything. And HOGS Im not saying it cant be a bad ground. It just goes away when the trucks warmed up and restarded. Thats why I didnt think it could be a wiring issue.
 
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