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Cummins question COLD weather.

darkshadow

darkshadow

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Friend has a dodge Cummins the grill is blocked off, so the truck will warm up.

But the problem he is having is that until the truck hits full operating temp, the truck WILL NOT go fast, he could hold it to the floor he will peg 2000rpms, it down shifts but the truck will not go faster then 35MPH

as soon as it hits 90* halfway on the stat, the rpm's fly to 3500 and he takes off like a rocket.

he has hurd that this is a common problem and that people take them in and the dealer removes something and it doesn't do it anymore.

whats the deal with this?

can it be remedied, is this a problem or a design?
 
I have never seen this happen, or heard of this. My dad's Cummins works great in the mornings, as long as he remembers to plug it in. If he doesn't plug it in, it can take an hour or more to warm up. I did a little searching, but I can't see anything that would appear to make this a design. It almost sounds like maybe the heat grid isn't working properly, and the air is too cold coming in. Trust me in that I am probably wrong, since I am not a diesel expert.
 
I don't know either, if it slowly got better then I would think something is wrong. But this thing has ZERO power until the stat gets exactly mid way then it just takes off, I thought it was either injection pump, or computer controlling something.
 
Computer could be controlling, but the way it sounds, the heat grid starts warming up much more once the water temp starts coming up. That is just the way it sounds to me though, and as I said, I could be totally off on this.
 
if it was a 12 valve i would say the grid heater wasnt cycling properly...but you said it will rev to 3500 so im going to assume its a newer computer controlled one so im not sure
 
1. He's got a 24v, otherwise it's a 12v with a governer kit.

2. The grid *should* have no effect on your friend's problem. The grid will cycle for about 4-5 minutes progressively when the truck is started cold and left in "park." But, as soon as you drive above around 25mph or so, the grid stops cycling.

That is not a common problem in those trucks, as I don't see that as an issue in the forums. I'll think about it an post back if I come up with something myself....
 
I am not sure of the exact year but I think it is a 2ed gen 24v almost sure.


I remember he said if he drops the rpms to less then 1000 then hits it it would speed up for a sec, then bog back down.



2. The grid *should* have no effect on your friend's problem. The grid will cycle for about 4-5 minutes progressively when the truck is started cold and left in "park." But, as soon as you drive above around 25mph or so, the grid stops cycling.
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could it not be working at all? needing the truck to heat up on its own?

Oh also he said it will not warm right up if it is parked. It will at most go halfway to operating temp.

he has card board down in front of his rad so that the whole grill is blocked off, but nothing for the holes in the bumper.
 
darkshadow said:
I am not sure of the exact year but I think it is a 2ed gen 24v almost sure.


I remember he said if he drops the rpms to less then 1000 then hits it it would speed up for a sec, then bog back down.







could it not be working at all? needing the truck to heat up on its own?

Oh also he said it will not warm right up if it is parked. It will at most go halfway to operating temp.

he has card board down in front of his rad so that the whole grill is blocked off, but nothing for the holes in the bumper.
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Think of the grid like a choke in a carb. You don't need the choke when you are driving down the road with the engine still not up to operating temp. The only difference with the diesel/grid is it becomes nearly useless as soon as the truck fires up and the pistons warm enough that they will ignite the fuel on their own without the help of the grid (this is a matter of a few seconds after complete combustion on start up).

It's fairly normal that the truck won't warm up very well just idling. I can leave mine idling in the driveway on a 35* morning for 5 minutes and coolant temp is only 90* or so. Diesels just don't build much heat idling. I've even had trouble in cold weather snowing where I can only do 25mph or so, and the truck starts cooling off....:o


Does he have any white smoke at start up? He's got to have either of two things wrong IMHO.

1. I'd say he's got electronics possibly going bad in the VP44.

2. Or, he's got a bad sensor someplace somehow causing the ECM to screw with power output? That sounds strange, but you never know.


I wouldn't worry about the slow warming up though. I can pull 10K up a grade at 60mph+ in 105* ambient temp and stay under 210* coolant temp. These Dodges have huge aluminum radiators in them to be able to accomplish that, which equates to slllooooowwww warm up in cold weather. It's even worse with a performance exhaust and intake.
 
It is not so much the slow warm up that is the problem, it warms up to operating temp with in 5-10 min of driving with the rad blocked.

It is a safety thing, merging in to traffic with a ball less truck is a little hairy at times.

confermed today 2001, and no smoke on start.
 
I have access to Cummins quickserve, if you can get me an engine serial # I can look it up.
 
sorry, but whats that do? :dunno:

ill try to get that today, doing some more framing with him in an hour.

you need the block #?
 
darkshadow said:
sorry, but whats that do? :dunno:

ill try to get that today, doing some more framing with him in an hour.

you need the block #?
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There is going to be a manufacturer plate on the engine listing HP rating, engine serial, manufacturer date, and something else I can't recall. Whenever you need parts for a Cummins engine, you give the serial number to any Cummins dealer and they can get the right parts for that engine.

Regardless, I don't know what that will do for yuor friend anyway. Running the serial is for getting parts, not telling what is wrong.


He is likely going to need to take it to either a dealership, or a good shop that knows diesels.
 
rjfguitar said:
1. I'd say he's got electronics possibly going bad in the VP44.

2. Or, he's got a bad sensor someplace somehow causing the ECM to screw with power output? That sounds strange, but you never know.
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that's what i think, the fact that its gutless until a certain point then its full power from then on sounds like a switch or relay not working properly, or a code keeping it from running correct. if it still has a warranty, by all means take it in and have the dealer work on it. let us know what you find out.
 
Cummins quickserve is for parts & service. :rolleyes:
Being that I am a Cummins certified tech I have access to all manuals & troubleshooting trees. :wink1:

The engine serial number will give me repair & troubleshooting manuals for that engine and computer system. Along with service bulletins, service parts topics, recalls, ect. ect.
 
I did not get it today I forgot, little busy. Is it just on the rad support?

Today I actually drove it, I started to think MAP, or TP sensor, there seemed to be very little throttle response I would leave a light slowly and it would shift once or twice, and level right off, but as I depressed the throttle more and more there was NO response at all, it seemed as if the throttle was not opening at all, unless I let off and stomped on it would it respond.

I will get the number on Monday.
 
IIRC the data tag is on the front gear cover on the left side, I believe it is also stamped on the ECM (engine control modual)

Generaly if a TPS or other sensor is going out it will throw a fault code and if it is active will light up the check engine light.

It sounds like it is derating untill the temp comes up for whatever reason.
There may be new software that needs to downloaded to correct this.

With a lot of drivability problems the first step is generaly checking the software phase and seeing if it needs to be updated.

But with a 2001 those issues should have been resolved by now. But ya never know. There could be an old service program that deals with that problem. I run into it all the time.
 
I never saw your last post, I took a quick look today but it was -20 so I said forget it.

today being so cold it would come and go, fast one minute the crappy the next on the highway, he called the guy he bought it off of (who was the 3ed owner) said it would always do it.

going to email him what you said see if he can get the number.
 
the IAT sensor had a big effect on power with temperature. take it out and clean it first. see if that helps or changes anything. then scan the ECM for sure. I have a full code list for the 2nd gen trucks. You could have a code with no check engine light.
 
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