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

[ALittlejohn]

I get an hesitation with my 2000 dodge with no lights and no codes. Talked to the dealer no codes unknown problem. Dearler replace LP about 15 months ago or about 34,000 miles. anyone have an answer.



Should I put the FASS on my truck?

 

[Sticks]

It would help us out a little to see what you have on your truck, and what kind of truck it is.



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[WadePatton]

me too

I now have a hesitation with no codes on my 2000 truck.



FP is fine. Filter may be old. No WIF light, but water is the only thing that makes sense right now. (It helps me believe that it's not the 44. )



Truck applicable BOMBS: DDUFM, DD3's, Max Flow fuel lines.



It's not consistent. It pulsate slightly at heavy throttle with box on. It may exist with box off, but it's hard to feel. I've re-done the pump tap/ground and it's all good. This stumble isn't nearly as bad as the one when the pump tap wasn't good.



New filter today. And nervously checking for codes again.

 

[RobbyRam]

May be the MAP sensor, but other than than I don't have a clue.

Bob in Sacto

 

[WadePatton]

Re-tapped the pump wire after running a direct ground and cleaning up all the battery connections. No change.



Road conditions prevent further testing for a few days.



Next to try swapping boxes, but Gap's box is out of town.



Wouldn't a MAP sensor out of spec set a code?

 

[Gary - K7GLD]

My '02 was doing that while towing the last few hundred miles of the long trip we just returned from - pretty much went away when the Comp was turned off, and was much worse when the engine was cold. Once the engine fully warms up, it seems to disappear or greatly diminish - can't seem to notice it with the trailer off the truck, either with or without the box on. Since I am also experiencing a slipping clutch with the Comp turned on, even on the lower levels and when accellerating briskly, I was thinking maybe a pulsing slippage might be the cause, but sort of doubt it.



I have guages, and have excellent fuel pressure at all times/loads, as measured right at the VP-44.



Like I said, with no RV load on the truck, and even WITH the RV, it is pretty much gone once the truck warms up, especially when the Comp is turned off. I sorta wonder if the fuel/timing map in the ECM is borderline for proper fuel delivery under heavy load and cold engine operation, and the Comp is aggravating the situation?

 

[WadePatton]

Welcome back stranger!



I haven't correlated it with engine temp, but then I always let the thermostat open before I hammer it.



Going hunting in the 4x4 next couple of days. Will get back on it next week.

 

[Gary - K7GLD]

HI Wade - and thanks for the welcome!



We went thru your beautiful state on our way to NC, where we spent about 6 weeks near Ashville visiting our oldest daughter and family. My wife was disappointed that she was unable to get any pretty picture postcards from your state as she did the other states we passed thru, since none of the places we stopped as we went thru had any available.



Lets keep this thread working, and see if a solution crops up - and I'll try harder to duplicate the hesitation without the 5er attached. I suppose another likely possibility is a partially clogged or defective injector that misbehaves more noticeably under load - altho' the hesitation seems too random for that to be the cause...

 

[Big P]

If you do a search you'll find that it's not an uncommon problem. My truck has been doing it for two years now, although it only does it in cold weather with the Comp on loaded or unloaded. I think Gary is right, it's probably a fault in the ecm and the advanced fueling/timing amplifies it.

 

[WadePatton]

Searching is how I found this thread.



My truck didn't do it last Winter. Hasn't been doing it for 94,000 miles. Box has been on it since 9/30 last year.



Something is amiss, and I'll find it.

 

[Gary - K7GLD]

I'm with Wade - SOMETHING has changed!



Mine started about a week or so ago, at slightly less than 20,000 miles on the truck and 1000 miles from home during our latest RV trip, when temperatures dipped down to frost levels - the truck has seen cold weather previously, at lower mileage, with no similar behavior - thankfully, SO FAR it's rather mild, and only when towing and until it is FULLY warmed up.



My truck has just over 20,000 miles on it, and only other changes in behavior are slipping clutch due to the Comp - and noticeably increased power as the miles increase and engine loosens up. Fuel filters are clean, and passing normal flow, fuel PSI at the VP-44 is as always, and I regularly (always!) use Power Service fuel additive for clean fuel system and added lubricity.



I am generally aware of theory of fuel/timing maps as used by engine control computers in our trucks that monitor various aspects of engine operation, temperature, engine load, speed,etc. , to determine best optimal fuel timing and volume.



I suspect that SOME conditions might place engine control near the edge of the "map" the computer references for fuel delivery and timing, and cause it to "hunt" for best settings under conditions the place it outside or near the edge of typical demands - and an added timing/fueling box would simply add to the erratic behavior.



In my case, added miles have somewhat altered the efficiency level of my engine - and MIGHT have also slightly nudged the fuel/timing mapping closer and "over the edge" at specific loads and speeds.



Other suspects so far are the throttle position sensor and airflow sensor - will eventually get to those if other more informed info isn't forthcoming...

 

[Ram4Sam]

Colder temps...

It seems the that the common denominator is the colder air temps. Could the key be the AIT sensor? Maybe when it detects colder incoming air in the manifold it is sending normal info to the ECM that the comp unit doesn't like.



Sam

 

[Gary - K7GLD]

"It seems the that the common denominator is the colder air temps. Could the key be the AIT sensor? Maybe when it detects colder incoming air in the manifold it is sending normal info to the ECM that the comp unit doesn't like. "



Good suggestion - and pretty well covered if a search on "IAT" is done on this site - as well as "ECM" and "MAF" - problem is, there seem to be far too many potential issues that various owners have tried - some worked, most didn't - and there doesn't yet seem to be any single magic fix that works the majority of the time...



BUT, I *DO* now wonder if most of this surging/bucking tendency is occuring primarily as colder temperatures are in effect - once it starts, does it continue still even after warmer weather is back?

 

[Big P]

In warmer weather, 40+ degrees, my truck runs fine on any fueling/timing level.

 

[jhutton]

I have this problem too (or I'd be foolish to be on this thread). I was fine untill the weather started getting cold enough to expect snow. I put 900# of gravel in the bed and proceeded to carry on with my daily commute as usual. It wasn't very long until the surging was very evident. Maybe a little less severe with cruise on. This characteristic is very proportional to the rate of power delivery I try to achieve. At steady speeds or gradual/slow acceleration the surging is very reduced and may not even be present. It's also clearely worse in relation to the engine and probably more so the block temp. On a 60 mile commute the last 30 miles have a moderating effect. Good blocking of the front end by covering most of the intake areas will pretty well stop it. I've found that a new fuel filter (2500mile change intervals) and not overdoing the additives are positives. So I pretty much think its the IAT circuit. Most of us pull some serious cold air with the BHAF's, Scotty's, etc we use for our mods.

 

[Gary - K7GLD]

OK, *IF* the IAT is the problem when exposed to cold temperatures, what if we "fool" it into thinking its a bit warmer than it really is?



Assuming the resistance of the IAT sensor goes LOWER as intake temps go colder (as is typical in resistance circuits), what if an appropriate resistor was installed is series with the IAT lead to make it think it ws somewhat warmer - or, possibly even a variable potentiometer that could be adjusted as seasonal temperatures change?



What is the measured resistance of the IAT at nominal temp, and does anyone know what the design resistance change is in relation to temperature in "normal" usage? I've seen this info posted before, but don't remember the values. Is it possible that indidvidual variations in manufacturing tolerances of the IAT's and associated circuitry in some cases is far enough out of range to cause cold weather fuel/timing problems?

 

[Gary - K7GLD]

WELL, I was full of beans on resistance change vs temperature for the IAT, at least in this particular application - here's a post in an old related thread made by Alan Reagan giving ohmmeter readings he did on a couple of them:



"I changed out the IAT with the new one from the dealer. Before installing them both, I did four temp tests for readings.



Old

30* 30. 1K

76* 9K

81* 8K

130* 5. 57K



New

30* 40K

76* 13K

81* 6. 87K

130* 4K



=========



Interesting to note that the thread that quote was lifted from had NOTHING to do wit power surges or "bucking", but only fuel mileage and EGT - so sorta leaves uss hanging as to possible additional effects of the IAT as related to power surges...

 

[Turbo Tim 1]

But, cold temperatures could be affecting a connector causing this situation. Welcome back around Gary, where is your ground for your comp located? I know it was already mentioned to some extent here, but this was my problem. Seems that the connector to the air intake horn wasn't making a good ground after having been installed and removed a couple of times for other work. It would be somewhat easy to check from the connector to the engine block with and ohm meter.

 

[Gary - K7GLD]

TIM - my Comp ground is the same as yours, and I do plan to try a better location for it - as well as checking various connectors for looseness - I suspect washing engines as some do might be a contributor to deteriorated connector contact over time, and carefully avoid washing mine other than wiping it down with a cleaning rag.



Anyone wanting more info on IAT function, do a board seach on "IAT resistance values", and especially read the thread on cleaning the IAT originated by Bowhunter, and the one of fuel mileage originated by Marco - dunno if Marco still reads and posts here, but his expertise in ECM programming as well as related computer engine control would sure help us with this surge and hesitation question...

 

[Turbo Tim 1]

Gary, just so you know I had a bad surging problem with mine and I chased it for a while, after talking with people from these boards and Justin at Edge Products I decided to run the ground wire directly to the battery and whalah my skip/surge/hesitation was gone. One of these days I am going to solder it directly into the harness but for now it is working.