Engine/Transmission (1998.5 - 2002) Surging

[Curious Dave]

Okay guys... I have had this happen off and on over the years. But I never seem to be able to figure it out. #@$%!

Driving down the road... and the truck feels like it is surging a bit. If I watch the boost I can see it fluctuate up and down a few pounds while maintaining a cruise @ 65. It isn't on cruise... Just maintaining the pedal. No hills, no load. Anyone have an idea?



Thanks.

 

[Curious Dave]

I really don't think I am the only one that has experienced this. Anyone familiar with the surging?

 

[JLandry]

Dave,



It could be so many things that without some diagnostic tests, it'd be pure guessing. I could see arguments being made that it's a problem with the APPS, the MAP sensor, the ECM, the or VP44.



It might be helpful to get a real-time engine analyzer like a Chrysler DRBIII or a Scanguage to see if you could correlate something to the surging in the hopes of narrowing it down a bit.



Good luck,



John L.

 

[Curious Dave]

Hey John... . Thanks, I am waiting for new fuel filters and will try that... . Afterwards I will see about the analyzer. Thanks again.

 

[Joe Mc]

Dave, are you running the stock turbo? Has this always been an issue? Did you recognize this after a bomb? If you change smarty setting does it still surge? I have a surge when cruising between 40 - 44 mph due to my turbo size and gearing etc. My supplier warned me I probably would have this issue and it's nothing for me to worry about - if it bugs me either speed up or slow down. This surge for me is annoyance, but since I was prepared for it I don't let it bug me - I just speed up or slow down.

 

[Curious Dave]

Joe, I am running the HX35 stocker. It has happened off and on since I have owned the truck (since new). I am on the second turbo and second engine. I am not sure when the first time was that I noticed it. This has been ongoing for years and not all of the time. I usually don't drive @ 6o but I was trying to play with the mileage. I have never noticed it any worse than any other time and it really isn't a hinderence. Just annoying and wondering what it is. It feels almost like the brakes are cuasing the truck to slow down briefly, like a quick tap of the pedal. Not even that extreme really. But one can see that it is a drop in boost. It is some sort of a fueling issue. What is causing it though... I have no idea. We'll see what the filters do, if anything.

 

[Joe Mc]

Dirty APPS? Does it happen when the cruise is on?

 

[aviatorman]

Surging at cruise

Dave: I chased a problem like yours for 2 years,, same symptoms. I finally fell off my wallet (not wanting to admitt something so simple was causing the problem) and bought a new MAP sensor from my local cummins house. Problem was fixed immediately. The new sensor has a different electrical connector, ,so you will also need to buy the harness wire adaptor ($19) to go with the sensor ( $51 ).

 

[Curious Dave]

My clockspring is broken. I quit using cruise a long time ago. I had 5 times where the truck was in cruise and the truck would briefly lose all power and then it would kick back on. Doing this was really hard on the entire truck so I quit using cruise. It did this since the truck was new and of course DC knew nothing about it. I gave up.

Now thinking about it... maybe these 2 things could be related.

aviator... What are the part numbers? I may throw some money at it.

 

[aviatorman]

Dave: I mis quoted the price in my post for the MAP, it's $87. 90 and thats why I resisted so long in replacing it (DUH-HUH). The old part has been superceded by cummins and the new MAP pn# is 4921505, that's why you need the new wire harness adaptor. Sorry I don't have the wire harness pn# , but the cummins boys know about it and have them in stock. A foot note on the MAP for ya , , my cruise control was also doing the very same thing as yours, and the MAP fixed it too. The MAP is on the left rear of the engine right in front of the IAT sensor. Not bad to change with the right socket.

 

[Curious Dave]

Cool... Thanks.