Engine/Transmission (1998.5 - 2002) Factory ECM has fast idle option in cold weather

[David_VT]

Say hi to Camas for me!... friends at WaferTech



Dave F might have more info but my understanding is that once the truck thinks you are in control of the vehicle it resorts to normal operation.



So, unless someone knows otherwise I would guess the driver that does not idle will not really benefit much.



As to cylinders, good question! Anyone??

 

[DIESEL RAM]

Hammersly,

It seems it would have to not inject fuel to what you are calling the "dead" cylinders. In a diesel there would be no other way to make them seem dead.

 

[jtisdale]

I dont see why it would have to "rotate" fuel to the dead cylinders, unless it was a thermaldynamic issue. Dont the jake brakes on the big rigs cut fuel to cylinders and make the valves do something different when the jake is turned on? And it is my understanding that one could run down hill forever with the jake on in a big rig with no harm to the engine, therefore wouldnt the same apply here, with the exception of the other three cylinders having to work harder? And when certain conditions (engine temp) are met, the program tells the engine to idle normally? That is what the whole idea is, to create heat in the engine a little quicker, right? My question is... if left idiling long enough will the engine ramp back down to 800rpm and then supply fuel to all cylinders? If it does, and left idiling even longer, will conditions be met to ramp back up to 1200 and drop out the other 3 again? Thusly maintaining a constant coolant temp and a constant cylinder temp? Or am I taking this a little far? I have had my truck reflashed, but it is still in the shop having other work done...

 

[David_VT]

My question is... if left idiling long enough will the engine ramp back down to 800rpm and then supply fuel to all cylinders? If it does, and left idiling even longer, will conditions be met to ramp back up to 1200 and drop out the other 3 again? Thusly maintaining a constant coolant temp and a constant cylinder temp?

This is my understanding: The numbers may be off but I think I have the algorithm fairly close. (Dave, tell me otherwise and I will fix this posting)



---- Initial start

1) vehicle in a true idle (not being driven as sensed by vehicle)

(any attempt to operate will return all to normal)

2) engine water jacket temp below ~140



3) air temp below setpoint 1 (~32F) then idle ramp up to 1200



4) IF idle at 1200rpm and IF air temp below setpoint 2 (~15F) then starve 3 cylinders to increase engine loading.



---- As vehicle warms in the idle condition

If engine water jacket temp above ~140 return to 6cyl operation and return idle down to normal

If engine water jacket temp below ~140 and

If air temp > setpoint 2, bring all cylinders on line.

If air temp > setpoint 1, ramp idle down to normal.



---- continued idle cooling vehicle back down

If engine water jacket temp drops below ~140 and

If air temp < setpoint 1, increase idle RPM.

If idle at 1200rpm and If air temp < setpoint 2, starve 3 cylinders.



---- the loop should continue until you run out of fuel ---

 

[DFormstone]

Fuel mileage?

Those of you that have had the reflash done noticed any changes in your fuel economy?

 

[Amianthus]

No change here.

My mileage and power have stayed the same since the re-flash. Although, it hasn't activated yet. It's just not cold enough. At least, not according to my truck.

 

[PKozlowski]

cold weather

Well I had it done to mine.

I see no differance in anything.

MPG stayed the same, the pulling power

is still there.

only thing is, it doens't work!!!!

it Has been cold enough to have it work

19 deg in the a. m. and the truck hasn't

been run for a few days.

I fire it up and Nothing... .

Nothing at all... ...

 

[Michael Hughes]

I would think that it would have to be pretty cold to get the intake air temp down to 32F with the grid heaters turning on and off. Next time it gets down to 30, I will hook my Snap-On scanner to the truck and see what the intake air temp is. I will let you all know.



I have the flash done and haven't see any difference in MPG or preformance.

 

[DFormstone]

Flash is done

Well I never thought I would ever look forward to sub-zero temps but I am.

My local dealers service manager was telling me that Dodge has had this program upgrade for 3 years but only released it recently. I wonder why they held onto it for so long.

 

[stephen bolger]

WHERE DID YOU HAVE THE FLASH DONE. I LIVE IN MEDICINE HAT. BOTH OF THE DEALERSHIPS IN TOWN SAY I HAVE TO PAY TO HAVE THE FLASH DONE.

 

[David_VT]

Cold enough but...... nada....

OK,

I know we have some DC mechanics lurking around. What's up with this fast idle sequence.



I have been cold enough to see something and nada!!!



I just came in and feel like an idiot who bought a 35$ rolex in Korea..... (2:30AM and cold outside, you get the picture)



So, I started the truck ice cold. Watched the grids cycle. Made sure the parking brake was set. Ran up the cab heater on full blast to make sure we did not build up any heat in the engine.



Guess what? When the SPA reading on the manifold temp dropped below 222 I gave up. To me that signified the end of any heater grid influence and the end of my anticipated glee at watching the thing run up the idle on it's own.



The dash gauge for the water temp never left the left pin (where it was when I started the truck). The truck had not ran since before noon (some 14+hrs).



---------------

OK, I did notice an ABS light on the dash that I do not recall ever seeing before. That came on for a few seconds after the truck started (following a good wait to start cycle). Maybe it is nothing but I thought I share if for our lurking DC mechanics.

---------------

I remain hopeful and don't mind if someone can tell me I did something wrong in the sequence.

---------------

Ambient temp was 22F.

 

[Ray Torresdal]

IAT

Might this mean that your IAT sensor is bad??? Just a guess on my part. I'm waiting to see how this works before subjecting my truck to the dealer service department. Ray

 

[DFormstone]

ReFlash

Stephen, I had mine done in Edmonton at Southtown Dodge. The foreman was real helpful and was more than willing to do it under warranty. A very pleasant experience.

 

[nwinters]

I have an appointment for Monday. I'm way out of warranty, does it matter if I have an EZ hooked up? Will it affect the update, or should I unhook it?



Nate

 

[JyRO]

Still a waitin'...

Howdy,



Some of y'all know me. Ole bomb-less JyRO. I haven't down anything to my truck yet. But this sounds cool (course this is not a bomb, or is it a warranty covered bomb?). Even though I leave my truck in the garage all night, and it probably doesn't get too much below freezing in the garage even in sub zero weather, there are time I think it would be beneficial. I can think of one particular time last winter when I drove my truck to work. When cranking to go home, the outside temperature gage read -5°F. It cranked over slower and was missing on at least one cylinder once it was running. I hated the thought of blowing fuel into that cylinder and it not igniting. It probably washed down that cylider good. It actually took it quite a while to get that cylinder(s) running.



The idle up would've helped me in that situation I think. I think this is a worthy reflash, but I'm going to wait to see if someone can post that it actually works.



My main question is this: For those of you who's hasn't worked yet, even at 2:30 AM at 22°, do you push the brake pedal when starting? I wonder if doing so deactivates this feature? Almost as if the computer thinks you're about to drive it and deactivates it. Is it possible you may be doing something else listed in the TSB that is deactivating this feature also? Please inform us. I'd like to hear that it worked for someone and that it's pretty cool. Thanks.



- JyRO

 

[David_VT]

I figured my post was long enough, but for more detail:



I tried several ways of starting the truck:

Parking brake on, only clutch depressed

Parking brake off, only clutch depressed

same as above with & without PE box on

and a few other wild ideas that were too crazy to mention



Naturally at some point the accumulated heat probably pushed the water jacket over 140F.



Time will tell... .



Ray, IAT??

 

[Ray Torresdal]

IAT

Intake Air Temperature sensor. There was a long thread a month or two ago about some of these being bad. I'm assuming it is using this to determine the ambient air temp??? Ray

 

[David_VT]

Thanks Ray, guess I missed the IAT thread.



I see that the heaters are cycling so I have to assume that the IAT is at least detecting the air is cold enough to require them.



Seems like justification to look into a software package to monitor the truck or even that palm thing.



D

 

[TowPro]

when I read the TSB, I THINK I read they have to reflash the ECM AND then turn on the option for the high idle. maybe they just reflashed it and never turned on the option? I will have to read it again.



TowPro

Originally posted by David_VT

Thanks Ray, guess I missed the IAT thread.



I see that the heaters are cycling so I have to assume that the IAT is at least detecting the air is cold enough to require them.



Seems like justification to look into a software package to monitor the truck or even that palm thing.



D

 

[Lil' Dog]

Originally posted by stephen bolger

WHERE DID YOU HAVE THE FLASH DONE. I LIVE IN MEDICINE HAT. BOTH OF THE DEALERSHIPS IN TOWN SAY I HAVE TO PAY TO HAVE THE FLASH DONE.

My brother in law just picked up his 2002 ETH-DEE 3500 on Friday in Lethbridge. He knows the dealer pretty well and says its a free-bee for purchasing there... . I can ask him what is required for the upgrade... .



J-eh