Well something went wrong at 232K miles. Diagnosing is what I need help with. I prefer to do my own wrenching. Oh, did I specify "automatic tranny"?

At freeway speeds in high gear the engine rpm begins surging up by 200 then back down for no apparent reason. It's not the tranny downshifting guys. It's the engine. I happens at light throttle settings and goes away with full throttle.

Now in my old Kenworth I'd layover at a good truckstop and give it the onceover especially checking for codes from the computer among other things. My Dodge shows no codes but the computer still might have registered something. All indications under the hood and under the truck are normal.

No guys, this truck is maintained properly, by me. I really doubt a fuel problem. I think it's electronic.

I've learned over the years to stay away from dealers. They guess, we pay... This symptom is not predictable. If a mechanic drives it it may not act up for him.

I was thinking either someone who has a similar experience or a dynamic bench test. I don't like other guys driving my truck.

Questions:

Can there be a code without the engine light indicating it's presence?

Anyone have expertise with speed regulation/sensor in this all stock engine?

Tks

JPS

 

I had an "electrical spike" in my 99 auto which the steelership fixed for 300ish. Mine reved up at lower speeds, would rev up and down quickly but no more problems since the fix.

 

I was going to post a similar question. Mine surges around 45 at light throttle. Once the converter reaches lock up, under no load it seems like it is searching for a gear. I called my tranny rebuilder that we use here at the shop and he says its a "normal condition" due to the amount of torque that the diesel puts out if there is no load it tends to search for a gear and best fuel economy. I don't know if this guy is blowing smoke up my because he doesn't know what he is talking about? But once you lay into the throttle and get out of the 45-55 mph range she runs like a top.

 

Check and clean ALLLLLL your ground cables, This includes the battery, engine, trans, and frame ground cables. It seems to be a fairly common problem on the 2nd gens.

 

Interesting replies guys. I will make sure everything is bonded to the same ground.

 

Mine does the same thing when running between 1250-1300rpm. Never higher or lower. It's not MPH dependant, it's engine rpm. I haven't checked he ground wires yet.
It's definately not a tranny issue (with mine), I'm on my second one and the truck has 206,000+.

 

Thanks Fathead for the comment. All I can say is that if the thing is in "lockup" the computer sure should know it and will not allow the tranny to search for gears or anything else. I think your mechanic is in over his head on this one.

I expect the Dodge Bros are quite aware of it but would rather not have an expensive recall unless they get told to. Of course I do tend to be cynical at times (and this is one of them).

And besides, I've driven mostly C-12's and Detroit 60's in the past few years. These sometimes have automatics but when they do they are the kind that does not have a torque converter. The computer just shifts for you, clutch and all while you sit there picking your nose and looking out the window or reading a comic book.

I don't like those but they do work pretty well with no power loss.

 

have seen this alot clean both positive and negative battery cables and check grounds on engine. very picky on battery connections make sure they are clean.... can cause alt. spikes giving false electrical readings just adding my two cents

 

There was a good article in TrailerLife magazine, January 2005, on this very issue. Yes, the first thing was check all grounds, etc, as indicated by 12 Valve. Perhaps this article is still availablesome where.