Engine/Transmission (1998.5 - 2002) Ever heard your Cummins Cackle?

[Gizmo 007]

I did a flat out run today on a long open stretch of road. I hit about 3200 RPMs, but I had to back out cause I was running out of road. The engine came back to an idle, but it was "cackling". It sounded like a powersmoke !!!! Seriously, it sounded like it was only hitting on two cylinders. It sounded cool, but couldn't have been healthy. It was only idling at about 450 rpms!

Ok. I was getting scared. I nailed the throttle and the engine went back to idling normal. I have a very curious nature, so I tried it again . After an evening of testing, here's what I've concluded:



While moving, if I rev to 3200 +/- 50 rpms, and immediately go back to idle, the engine cackles and idle drops to 450 RPMS. Touch the throttle and operation returns to normal. Best I can figure, I've found a bad computer glitch. Humm, I can have some fun with this.



The best part is the looks I got when I let it cackle as I rolled up to a stop light. People gave me this saucer-eyed look and tried their best to get out of the way! See, our trucks can do neat tricks that we don't even know about (and probably don't want to )

 

[jerrethomas]

only you could discover this one!!lol

 

[John Berger]

You might want to give Father Karras a call!

 

[HoleshotHolset]

This may or may not be related to your issue... but here's some more info... .



PSD's and GM 6. 5L TD's will cackle and make all sorts of racket on deceleration with your foot off the soot pedal.



Using compression braking on either of these engines while slowly going down a hill in a low gear will cause the engine to receive NO fuel... . and just as soon as it's at the right conditions for idle it'll receive fuel, cackle and then return to normal.



It's not a software bug, it's the nature of the beast.



Matt

 

[Gizmo 007]

I didn't think about the lack of fuel, but here is the kicker... It will continue to cackle as long as I don't touch the accelerator. I would think it would get enough fuel eventually.



Guess my next order is to find my fuel pressure tester and see what the pressure does as this happens. I may have a fuel delivery problem... hmmmmm.

 

[Big P]

Gizmo, my truck has done it maybe once or twice under similar conditions to yours. I never thought much of it until now.

 

[HoleshotHolset]

That may or may not be a bug... . interesting... .



So you are saying that once it starts cackling... it will continue NO MATTER WHAT until you hit the throttle?



Now I see what you mean about it being an attention getter...



Matt

 

[Big P]

That's how it was for me.

 

[HoleshotHolset]

I wonder if it's dropping cylinders like the cylinder contribution test.....



Interesting... .



back into the lab... .



Matt

 

[Terry]

I'm sure I hear my Cummins cackling every time I blow by a Power Smoke or a Dura Mini.

 

[Steve Campbell]

Not to be a pesimist....

But there was a thread a year ago talking about the injection pump siezing up when going from full throttle, hard pull, to no throttle after the installation of a fueling box. Perhaps you have found what happens if your injection pump is on the middle ground!!!



Then again... it sound like a computer glitch.

 

[Big P]

The one or two times my truck did it, it had only a timing box and DD2's.

 

[PRout]

Sounds like testing this "interesting phenomenon" could get expensive.

 

[Gizmo 007]

Holeshot, your dead on. It'll keep cackling until I move the accelerator, then it will quit.



Ever heard a powerstroke w/auto transmission coasting to a stop and noticed how the engine sounds just as it comes to a stop? That's exactly what it sounds like!



I tested the fuel pressure this weekend and it checks out fine. I checked the pressure normally and when it was cackling. Both read about 14 psi. I'm going to call it the computer's fault. Maybe it's just not communicating fast enough . Never gives me any trouble. Just touch the pedal and she's good as new.

 

[98rammer]

is this a cackling, stumbling, or an idle knock? the PSD's cackle and knock are two seperate things. yes, they're based off the same fuel line problems (check valves, small fuel lines, uneven length fuel lines, in-tank gaskets leaking, etc. ). But the idle knock is simply an idle knock. the cackle is sort of like the revers sound of the motor at 1400-1800. the cackle is also some what hollow sounding--basically you have to knock what you're listening for in order to find it. just clarifying here...

 

[Gizmo 007]

Sorry, rammer. I meant just the sound when the powerstroke cuts out during coast. There is not a problem, per say, with my engine, just a strange phenomenon. I didn't mean that the problems are related. My engine cackles because only 2 - 3 cylinders are firing when the computer goofs up. I went back and re-read my last post, so I can see where you are comming from. Sorry about the confusion.

 

[98rammer]

Originally posted by Gizmo 007

Sorry, rammer. I meant just the sound when the powerstroke cuts out during coast. There is not a problem, per say, with my engine, just a strange phenomenon. I didn't mean that the problems are related. My engine cackles because only 2 - 3 cylinders are firing when the computer goofs up. I went back and re-read my last post, so I can see where you are comming from. Sorry about the confusion.

ah, sorry, didn't mean to come off harsh there as i just re-read it. you know, the only way to get rid of the problem is to get a better truck like a 12valver

 

[Gizmo 007]

Originally posted by 98rammer



you know, the only way to get rid of the problem is to get a better truck like a 12valver

Ouch... That hurt. Aw, 24 valves ain't too bad. Got more top end that a 12 valver . Just ask drice.

 

[StakeMan]

Could it be that the timing isn't returning to an idle setting?



Who let that under-valver in here?

 

[98rammer]

Originally posted by StakeMan

Could it be that the timing isn't returning to an idle setting?



Who let that under-valver in here?

i'm not wanted:{ nah, someone forgot to lock the back door:-laf



i can put up a good fight i f i have to , what happens when you put a 4k gsk in a 12v for top end without the 24v having the drag comp or something of that nature?





uh oh, i can feel that wrath now...