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

[emjay]

Isn't there an idle switch or switches contained in the APPS assembly aside from the sensor itself?

 

[MCummings]

My truck will do something similar,, but only when I come off of a hard load (Not a no load 3,200RPM)



If I let the truck idle for say 30 seconds,, then run it hard through 2nd and 3rd and at 2,700RPM WOT I just let off, push in the clutch and hit the brakes the truck will fall well below idle, and sounds exactly like a ton of air in the lines,, the truck shakes back and forth and the tach bounces about 75-150 RPM +/- from idle.



I do have a normal idle speed though,, just 75-150 +/- from idle speed (not 450RPM)



Sounds like it's firing real good on 3 cylinders and real soft on the rest. Has a very sweet Lope,, Blap, blap, blap,blap, blap,,, just like a 12V with an insane GSK



I am thinking bigger than stock injectors are confusing the ECM, and Injection pump computer.



I know my truck has a small bump (lope) at idle all the time,, more when hot,, It actually moves the truck around a little, but it is more noticable in sound from the stacks.



Just my $. 02



Merrick Cummings Jr

 

[Gizmo 007]

ok rammer, don't make me come over there! I'd hate to have to show you up now . Nah, I'll admit it, a good 12 valver could get me almost any day he wanted. But that's just because I have a six speed



emjay, the apps sensor and idle validation switches(2) are all in one unit. True, one may not be functioning properly, but I would think that it would go back to and idle and not rev up? (I was playing with it one day and one of the idle val. wire pulled out of the harness. I couldn't make it come off idle. Took a minute to figure that one out ) But I don't know, I'm just guessing here.

 

[emjay]

Yeah, I'm not sure what those switches actually do, either. I was thinking at least one of them is used to "qualify" a true idle position; my rationale is that if it is intermittent, it might explain the odd behavior.

 

[Big P]

Well, this post has been buried for a while and unfortunatly I get to add to it. I put a Comp box on my truck sometime around Sept-Oct. Not at first but soon after with the box on level 5x5 and getting on the throttle hard while shifting through the gears, then let off the throttle suddenly and stepping on the clutch in would cackle pretty consistantly. It also got progressivly harder to get the cackle to clear up. This past month it would do it every time under these same conditions, but only with the box on 5x5, but I've been driving mostly with the box off for most of the winter. I thought it was a cold weather/box issue. Well yesterday while taking a friend for a ride in the all mighty Cummins , I get on the throttle with the box on 5x5, ya' know to show off a little. Well when I'm done bang'n the gears I step on the clutch and the motor died. This wasn't supposed to be part of the show. Anyways the injection pump is gone. This has only been a part of my bad luck lately!

 

[Gary - K7GLD]

UNH-OHHhhhh!



That turned out to be a "here, watch this - let me show ya how to blow up an injector pump" bit...



Or maybe a "let me show ya how to spend $1500 REAL fast"...

 

[Big P]

Gee, Gary, I can't figure out why it failed. After all I have a pusher pump.

 

[Gizmo 007]

Man, ouch, that sucks. Mine did the exact same thing, only my pump is still running. Hate to hear that .

 

[Gary - K7GLD]

"Gee, Gary, I can't figure out why it failed. After all I have a pusher pump. "



YUP - a curiosity - did you ever have a LP failure prior to adding the pusher, and do you use any lubricity additive in your fuel on a regular basis?

 

[Pit Bull]

Sorry to hear about your problem. I will draw from your experience and not do this to my truck. Thanks

 

[Chipstien]

Nothin more embarrassing than showing off and the truck croaks. :{

 

[Gary - K7GLD]

Personally, I'm more than a little curious about this - several fellas have reported the same phenomena - and MP even had a pusher pump on his, so pretty unlikely fuel starvation was the cause...



I'm wondering if a burst of high-RPM operation, and sudden backing off the throttle, somehow "confuses" the ECM - causing erratic operation of the VP-44 fuel solenoids, which then places unusual stresses upon the fuel injector pistons... Much like an exhaust brake - but potentially far more violent, due to the uncompressible nature of liquids...



Certainly something to think about...

 

[Big P]

I can deal with the embaressment, it's the wallet that's been taking the beating lately. And I didn't get off the throttle quick enough to bark the turbo. I also used to have a cold weather shuddering problem with the Comp box on in any level, however within the past month or so it changed from a shudder to weak performance in mid-level boost range 23-28psi? Under full throttle it still ran good.

 

[Pit Bull]

Originally posted by MPagnucco

I can deal with the embaressment, it's the wallet that's been taking the beating lately.

If you can't do the time, don't do the crime

 

[Chrisw]

MPagnucco my pump did the same thing about a week ago. I was showing my truck off and all when it died at a stop light. Before I spent the money for a new pump... . Thank god I called PDR and they told me to take and loosen 3 injector lines and turn the truck over till the fuel started coming out. it took 3 tries of about 15 seconds each time. after that It started back up. PDR said they have seen it before. and told me to look for a pump in my future



give them a call

 

[Big P]

Chris, unfortunatly I think that you might be in my situation eventually too. I had the truck towed to a local diesel/performance shop and they did get running in the way you described. The also did further diagnostics on it and determined that it was going south. Like I said this is the first time it died on me, but the clackle was starting to happen 95% of the time after full load with the Comp on 5x5. Anyways I'm going to have it replaced because I really don't trust the reliability right now.

 

[jtisdale]

Add me to the list...

The weekend after New Years, my wife and I were coming thru town when I spied a fellow CTD owner/buddy's truck sitting at the filling station unattended. While he was in paying for fuel, I drove into the next parking lot over, about 250 feet away. I pointed my truck towards the open area between his truck, and the door, and turned off my lights. (We always do this kinda stuff to each other) When he came out of the door, I waited till he was about half way to his truck, and I lauched in 2nd REAL hard. Under "foot to the floor" acceleration I came flying towards him, then let off the go pedal and stabbed the brakes. After I quit laughing, and he cleaned out his shorts he asked me why my truck was idling so neurotic... about 400-500 and seemed to be wildly missing. I reved it abit, and it returned to normal.

This must be what you guys are talking about. I just figured it to be a glitch.

Since then, I have heard comments of vp44's biting the dust after going from wide open under load to zero throttle.

 

[Big P]

jtisdale, I don't want to get you nervous but that's how mine started. It would clear up just fine with a touch of the throttle at first but towards the end it needed to be put under a slight load to clear it up.