Engine/Transmission (1998.5 - 2002) hesitation with no codes

[Gary - K7GLD]

OK - a bit of a revelation to some of you guys using the stock Cummins black bolts as grounding points... .



Those bolts are ANODIZED, or coated with a non-conductive coating that creates the very real potential the they will NOT provide a grounding path for some of your aftermarket installed electronic stuff like the Comp or similar.



The coating is easily removed with a wire wheel, grinding ot sandpaper - and the threads need a good hit with a wire brush as well to assure a good ground potential where they thread into their attachment point.



A real eyeopener is to check for electrical continuity from the head to the threads of one of those bolts with an ohmmeter!



On mine, I wire-wheeled the threads and the underside of the bolthead and then used stainless electrical star washers for continuity and also a decent application of no-corrode on all contact points including the bolt threads.



Dunno if that was a contributing point or not, but a good point to check anyway - and interestingly, DC/Cummins themselves use those bolts as grounding points at various locations, including the grounding point for the grid heaters!



Without attention like the above sure doesn't seem like a good idea to me!

 

[WadePatton]

YES

Whoever related this problem to ambient air temp was barking up MY tree. It warmed up to the 40's today and I couldn't reproduce the hesitation.



I think I may have gotten a bit of hesitation at part throttle, but it was GONE at WFO.



I still have a huck-a-buck on 5x5 at part throttle, but I've always had that.



Anyhoo. I'm planning on a new IAT sensor. This one has 95k on it.

 

[Gary - K7GLD]

WELL, since returning to our warmer California climate, and detaching the 5th wheel, I can't duplicate the problem either - it only occurred 3 consequetive mornings from Texas thru Nevada when overnite temps dropped below freezing - we had last filled with fuel at El Paso - so wonder if winter fuel might have been a wild card?



Since the ECM is largely composed of solid state devices, and they frequently display erratic behavior in cold temps, I sorta wonder if that might be a factor - some of my rather expensive solid state ham radio stuff also gets balky when the temp gets down that low, and in fact, the display on my mobile radio installed in my truck was also functioning poorly during those cold mornings until the temp got higher!



Added to this, is the fact that it took a LOT longer warmup for my hesitation to go away than just the time it took for coolent temp to normalize - which would seem sorta reasonable IF the ECM is the base problem - it sits off the engine and would most likely take noticeably longer to normalize in temp than the engine itself.



At any rate, since I can't duplicate the problem, and am RARELY likely to encounter those same conditions and circumstances again, guess I'm through here, unless we get some significant additional info...

 

[JTBMC]

Mine does the exact same thing, it fisrt started last winter when I was running the Edge EZ, now its back with a vengence, but only while towing, it will not buck running empty no matter how I try. I've noticed as the temps drop mine starts to buck with the Comp on. If I turn it off the bucking goes away. I will change the ground to the Comp and will be pulling tomorrow and post the results.

I have replaced the EZ with comp, as Edge and I both believed the bucking to be caused by the EZ, now I'm not so sure.

Just wondering if anyone with the Diesel Dynamics UFM version of the Comp suffers from the same surging, bucking problem that we have sense their timing feature is different.

TJ

 

[DavidC]

Originally posted by tjlaffite

Mine does the exact same thing, it fisrt started last winter when I was running the Edge EZ, now its back with a vengence, but only while towing, it will not buck running empty no matter how I try. I've noticed as the temps drop mine starts to buck with the Comp on. If I turn it off the bucking goes away. I will change the ground to the Comp and will be pulling tomorrow and post the results.

I have replaced the EZ with comp, as Edge and I both believed the bucking to be caused by the EZ, now I'm not so sure.

Just wondering if anyone with the Diesel Dynamics UFM version of the Comp suffers from the same surging, bucking problem that we have sense their timing feature is different.

TJ

Ask and you shall receive.

http://turbodieselregister.com/forums/showthread.php?s=&threadid=85178



Dave

 

[JTBMC]

Howdy Dave,

My VP connection is still ok sense the last time I checked it and I am keeping a watchful eye on it. I have also cleaned the ECM,PCM, APPS,FASS pump MAP & IAT plugs with electric parts spray cleaner and reapplied dielectric greased them.

I will be pulling 16. 000 pounds of Hay in the morning and hope the surging doesnt come back, as I now have a new Comp and have ordered the Grabber, to get rid of the scotch lock, I checked the S/L connection and it appears to be good and is still greased well, and will be changing the ground conections before I leave.

TJ

 

[DavidC]

TJ,



One other note I found (I believe it was in the service manual) was that the fueling system also monitors the cooling system temp. . From what I could tell it is from the sending unit for the guage. Do not know if this helps anyone but it does add another piece to the puzzle. Good luck with the tow and let us know the result.



Dave

 

[Big P]

See, I told you Wade.



BTW, I've replaced my IAT sensor twice with no change. Don't waste your money. I still think it's in the ecm somewhere.

 

[WadePatton]

UFM

I have the DDUFM. Speaking of timing--that's sorta what if feels like. It's a real soft bucking--unlike the bucking that I got when my wire-tap was the culprit (long ago).



Today is was in the low 50's and the only bucking I got was the clutch turning loose every now and then. (Yes, Peter and I have worked out a swap)



Cleaning up all the connections is a good way to spend some time under the hood, but it didn't change anything on my ride.



So the IAT ain't agonna fix it? Guess I'll just have to P-foot around on cold days. Or drive the 12v.



I'll try restricting the underhood airflow to seef that helps.



This would be a MAJOR issue for me if I lived in one of those cold places.

 

[Gary - K7GLD]

"that's sorta what if feels like. It's a real soft bucking"



YUP - exactly what mine did as well - so light, I at first wasn't sure but what it was imperfections in the road surface causing it. But the more I read and think about it, the more convinced I am that it relates to the ECM, and various internal circuit component sensitivity to cold temperatures - sorta strange if true - since so many of these engines commonly operate in pretty cold climates and conditions - you'd think it would have been long since identified and corrected...

 

[Big P]

Gary

You'd think it would have, but the common here seems to be that 95% of the people affected have performance boxes. Dodge and Cummins are testing stock.

 

[WadePatton]

ambient air temp

Okay, I'm satisfied that air temp plays a role in this. Last night it dipped into the 20's again here and the stumble came back.



"Winter front" is in order.

 

[Gary - K7GLD]

OK - it would REALLY help to isolate the condition, and eliminate deadends, like various sensors, etc...



Since the ECM has evolved as a primary suspect, maybe some of you who live in cold climates, and predictably have the problem, can try a bit of an experiment:



Try a low wattage heat source - a small heating pad or low power heat lamp as closely focused and confined to the ECM as possible - leaving the rest of the engine to remain in a cold condition - then, with the ECM alone "preheated", see what happens on a cold morning.



Sorta like the engine block heater, only different...

 

[jhutton]

As a follow up to an earlier post of mine; really covering the front radiator and all the way down to the bottom of the front bumper and extending this as far to the sides as possible totally eliminates all my hesitation and stumbling. Ave engine temperature is up by about 20 degrees by the factory analog gauge--higher than I've ever seen it even in 105 degree days. Turbo cool down is certainly much longer, but in town stop and go temps are lower than what I see on 60 mile commutes at 65-70mph in mountains.



John



Banks Power Pack; Big Hoss 5; Power Elbow; Edge EZ; DDII, K&N version of BHAF; Star Clutch, Gear Vendor; 285/75-16; HO '01 6sp.

 

[Okie-Go]

Mine does it also. Going to the friendley Dodge dealer on Monday to let him keep it for 3-4 days while I am deer hunting. Got to get this fixed as it is driving me crazy. Does it when warm outside and when cold. I have confidence in this guy and will post in a week or so when I get back.

 

[Gary - K7GLD]

One more follow-up question - does this condition stay pretty much the same level when encountered - or does it appear to get progressively worse over time? If mine only does it now under circumstances I rarely encounter, is it likely to worsen until it DOES start showing up in my normal driving?



I can just imagine taking mine in for dealer repair - an extremely rare condition that only shows up in below freezing weather, and when towing...



NO WAY I'd EVER get that found and fixed!



And for THAT matter, even if they DID swap out the ECM (assuming that IS the problem!), I'd have no assurance the replacement was any better - and have great difficulty myself in testing it to find out!

 

[Big P]

"an extremely rare condition that only shows up in below freezing weather, and when towing... "



That seems pretty accurate. Accept it's under about 40 degrees.



My truck only does it with the box ON. Running only my DD2's I don't feel anything.

 

[JTBMC]

The bucking continues,

As you said Big P, no Bucking when the Comp is off while towing, mine will not buck unless I'm pulling and only above 21 pounds of boost as it powers up to pull the load over the hill.

Just running on my injectors and boost feature of the comp while pulling she is a smooth as silk.

Mine seems to get worst if I leave the box on, started out as a suttle surge. Like you started the pull up the grade as though I was lightly taping fuel petal over and over again, fueling & de-fueling, as it progresses the truck feels like I'm running a wash board road. Mine will also buck at 60 degree's F, it doesn't have to be in the forty's. But never does this in the hot summer months.

TJ

 

[Gary - K7GLD]

We'll never know exactly WHAT causes the problem - or how to correct it - until we isolate it!



Those like me who rarely encounter the problem due to the climate and circumstances we operate in are STILL at risk if the problem gets progressively worse, or if we at various times DO use our trucks in the circumstances that typically cause the problem to surface - an RV trip up north in cold weather, or the owner who moves from Arizona to Wyoming...



We really NEED to nail this down and ISOLATE it!



And only you guys out there who DO encounter it regularly are in a position to do that! The rest of us who have found we are at at least a small degree of risk need several of you to do as suggested up above in an earlier post, and try some method of preheating the ECM to once and for all either ELIMINATE it as the source, or actually prove it IS the source - until that is accomplised, we're still simply flying blind...



There are a handful of you fellas out there in the colder climates who are in a position to really help the rest of us out - how about it guys?

 

[Big P]

I would if I could

Pre-heating the ecm will not help. I first encountered this problem while towing a snowmobile trailer to VT. Through CT and MA is pretty flat, never really had a problem, but once you get into the hills of VT it will show up. So as you can imagine by the time I'm in VT, oil, coolant, and everything else is up to full operating temp. I remember reading somewhere on this site that the ecm will alter timing according to air temp. I know the the IAT provides this info to the ecm, but what does the IAT acually measure, ambient air temp or air after its been through the turbo and after cooler? The key might be adding some type of resistor curcuit to the IAT to fool it into seeing higher temps, which BTW I would try if I had the ability to do so.