Engine/Transmission (1998.5 - 2002) Instantaneous power loss when pulling really heavy

[pdxkevinc]

I have a 98. 5 24v, manual trans (5sp), 4x4 basic stock truck and 109,000mi. The only guage I have is a fuel pressure guage. I have had an intermittant problem the last 3 times I have towed my 5th wheel.



When pulling real hard *up steep hill, passing, etc) with my 5th wheel, I have hed 5 or 6 occasions where it felt like total instantaneous loss of power for just a fraction of a second. A real "thump" sort of feeling. It is driving me nuts

because there are no codes. I have a new lift pump and like I said the guage shows no fuel loss.



The odd thing about this problem is that it only happens when I have my foot mashed to the floorboard and so far only in 4th and 3rd .



Cummins says that is really doesn't sound like fuel or injectors since I have full power back immediately. They think it sounds electrical.



Do these symptoms sound familiar to anyone? I have searched the forums, but only find lots of posts about hesitation and shuddering and so on. Nothing about a high-RPM instantaneous loss of power (the lasts a fraction of a second).

 

[CumminsAholic]

Is it sort of like a gasser missing? I mean you can feel it miss/ loose power almost like a cylinder isn't firing? My truck does something like that. I can't figure it out either. But it doesn't do it all of the time. It's almost like I'd turn my fueling box on off on off on off on, but it always clears out. It'd not that much of a power loss, but it's definately noticable I'd say at least 50 hp.

Corey

 

[obert]

I had a bad connection at the MAP sensor causing occasional cut back, didnt always set a code, but would happen at any given RPM or load.

Could be an APPS issue, mabey?



Then there's always the fact that the early VP44's are most failure prone -- mine only lasted 50k miles... .

 

[obert]

turn my fueling box on off on off on off on

I get a "buck" like that at around 2700 rpm, very light throttle. The fuel light flashes on / off in rythm to the buck. I think its a bad spot on the apps, but since I dont normaly drive for that scenario to occur, I just ignore it

Or (hopefully) just too much sensitivty with the box on at HI eng. speed.

 

[CumminsAholic]

I dunno. I'll get a similar thing at low throttle when it's cold, maybe when the grid heaters come on? It could be the vp, I'm already on my second one though. I reset the apps by moving it as per Bill k, that helped my shifting problems for a while anyways. But it didn't help the "miss". It's not really bad, but it bugs me and I'd like to figure it out.

Corey

 

[Mhannink]

well being an auto tech i wold say get your modis and start doing wave forms on your apps but thats an 8k tool. i would say to do a voltage test of the output wire to the computer and see if theres a ''blip'' in the readings. in a wave from it would show up as a drop in the voltage only for a minute then go on like normal. on the multimeter i will drop voltage. if you move the apps slowly to wot you should see the voltage go from almost 0 to almost 5 volts any sudden change while u move in this direction will indicate an open in the sensor wiring and means you need a new one. well good luck w/ that and i hope this helps

 

[lumberjack98]

maby

On my truck 98. 5 24v auto while searching for dead pedal probablems (no codes) i found that at the drivers side below the power distribution box that the shock is a stud type and that the wiring loom for the injection pump, map sensor etc was sitting on top of the stud and had wore/punched a hole through 7 of the wires in the loom not all the way through but most of the way broken. i had to loosen up the loom and cut it open to solder and heat shrink everything back togeather then secure it out of harms way. have also heard where the plug from this loom plugs into the power distribution box has had some loose, corroded issues. Hope this helps

 

[obert]

have also heard where the plug from this loom plugs into the power distribution box has had some loose, corroded issues. Hope this helps

Thats interesting... unrelated, but I'll have to look at that-- might explain why sometimes I have to unplug the trailer relay to get the trailer lights to work right. If they dont turn off, unplug relay and they work on/off just fine, till they wont turn on, the the relay goes back in till the cycle starts over.

 

[pdxkevinc]

it is not like a gasser missing... it is a almost like a total loss of power, but only for a split second...

 

[WadePatton]

There's a "intermittant stumble" reflash for the 24v. Don't know which years exactly, but my 2000 had it. Look for a TSB or post of that nature.



It was exactly what you say about "split-second" cutting out, but it was unpredictable. No way to reproduce it, it just happened---well, shall we say, intermittantly. I had mine flashed and have put 50k or so more miles on it without a recurrence.



That being said, I'd hook a scanner to yours and try to reproduce it while monitoring--which may mean hooking the 5er up and all.

 

[pdxkevinc]

thanks for the info... I need to find a good shop with a dyno I think

 

[JKinney]

I believe smarty can do the reflash