Archived 1999 2500 Intermittent Loss of Power

[DAMorlock]

I've posted this before. Since posting have replaced fuel filter, fuel is clean,replaced lift pump (17 psi), replaced VP44, turbo and waste gate is ok. There are no codes. Works fine, then looses power. Any clues would be appreciated.

 

[MChrist]

When you say "loses power", do you mean a slight loss of power, or a loss like your accelerator pedal isn't connected to the engine. Otherwise known as "dead pedal".

 

[DAMorlock]

When going up a hill at 40 mph, there is nothing I can do to get beyond 40 mph (shifting to 4th gear, flooring the accelerator, pumping accelerator).

 

[ChrisOlson]

Is the Loss of power only on that hill. have you tried down shifting to 3rd gear going up that hill?? How steep is the hill.



is there a loss of power otherwise??

your dodge was rated at 235 hp and 450 ft lbs of tourque.

no codes??? any other information for us to help you trouble shoot your problem.

hmmm join date 2004

with 8 posts how long have you had this truck.



GET A FUEL PRESSURE GAUGE!!!!



chris

 

[MChrist]

So it doesn't sound like dead pedal, because when that happens, it's like your foot slipped off the pedal and you have no power at all. Have you checked your TAG2? Maybe something happened to that. If you had an EGT gauge, you would see the temp spike. Air filter, fuel filter? Too steep of a hill?? My '98. 5 has same motor and trans as yours, and I can pull a 12,400# trailer up a 6% grade and the truck weighs 12,000 to start with. I start the hill at 55 and a mile later, when I crest it, I'm around 48.

 

[MChrist]

And mine has 3. 55 gears...

 

[DAMorlock]

The hill was an example of the power loss. Normally I can accelerate up that hill in fifth gear with no problem. I cannot accelerate of level ground when this occurs. I bought the truck new in Oct 1999. The fuel pressure is 15-17 psi. I am installing a fuel pressure gauge when I get the truck back home. Air and fuel filter are clean. TAG2 was inspected and is clear.

 

[sslechta]

Based on your description I would say I had a similar problem a couple of years ago.



My truck would be running fine and then 'lose power' like you described. I could mash the go pedal to the floor and the truck just would not respond. I could not replicate the problem at will (it would come and go with no clues as to why) so when I took it to my mechanic he checked for codes and there were none. After much discussion we decided the VP44 was going bad so it was replaced. On the drive home immediately after that repair, the 'no power' condition occurred again. It stayed in its 'no power' condition long enough for me to limp it back to his shop. Again, no codes. He connected his 'Star Scan' tool (I think that's what it is) and we drove around so he could analyze the problem. During this he found that the truck computer was reading 0 PSI boost even though my gauge showed 1-2 PSI. We swapped out the boost sensor (it might also be known by some other name) and that fixed the problem. When the computer thought there was no boost, it simply did not allow additional fueling (this is my understanding). The problem has never happened again.



In short, I replaced an expensive part unnecessarily when an inexpensive part was the culprit. Sometimes you just don't know. I hope this info helps someone.

 

[DAMorlock]

I forwarded your info to my tech. I hope it solves the problem. I'll be back, hopefully with results. Thanks to all.

 

[Sticks]

Based on your description I would say I had a similar problem a couple of years ago.

My truck would be running fine and then 'lose power' like you described. I could mash the go pedal to the floor and the truck just would not respond. I could not replicate the problem at will (it would come and go with no clues as to why) so when I took it to my mechanic he checked for codes and there were none. After much discussion we decided the VP44 was going bad so it was replaced. On the drive home immediately after that repair, the 'no power' condition occurred again. It stayed in its 'no power' condition long enough for me to limp it back to his shop. Again, no codes. He connected his 'Star Scan' tool (I think that's what it is) and we drove around so he could analyze the problem. During this he found that the truck computer was reading 0 PSI boost even though my gauge showed 1-2 PSI. We swapped out the boost sensor (it might also be known by some other name) and that fixed the problem. When the computer thought there was no boost, it simply did not allow additional fueling (this is my understanding). The problem has never happened again.

In short, I replaced an expensive part unnecessarily when an inexpensive part was the culprit. Sometimes you just don't know. I hope this info helps someone.

Seems like the truck should have been trying to add fuel rather than go into limp mode unless the ECM was reading an open in the MAP circuit, but that should have set a code. Now if it was reverse and the MAP sensor was reading over 22, then it would defuel.

DAMorlock - To me, this sounds like an APPS sensor issue, which is notorious for not throwing any codes until it goes completely dead. If the truck is not setting any codes at all, then a drive with the scanner hooked up and monitoring the MAP, APPS, Fueling, and load sensor reading to see which one is out of whack.

 

[DAMorlock]

The bottom line is the MAP sensor was bad. No codes ever showed up and the sensor was putting out good info to a monitor. Confusing and expensive. Thanks for all the help.