Engine/Transmission (1998.5 - 2002) slight hesitation in '01 high output - 6 speed

[bboxall]

My '01 high output has a slight hesitation at about 1700-1900 rpm. Noticeable in 4,5, & 6th. If you press the throttle on down it will accelerate fine but you feel the stumble, below that RPM it is smooth. No starting or idling problems and not down on power at all. I checked and no error codes are stored.



-Not equiped with fuel pressure gauge.



Any ideas would be appreciated.



THANKS!

 

[SBall]

Russian-roulette!

Personally I feel running these trucks without a fuel pressure gauge is taking a real chance, and hesitiation under load could suggest a fuel issue. I'd first check/replace the fuel filter and check the IAT sensor, but I'd have that fuel pressure checked before i drove it any more. You don't want to starve that injector pump! $$$$$$

 

[bboxall]

I replaced the fuel filter first thing. The lack of a fuel pressure gauge will get solved ASAP.

 

[ESorensen]

stumble

I had the same symptoms a couple of years ago. It ended up being the lift pump. I'm now on the second one; replaced last week but I also installed the guages (mandatory adddition IMO) along with MAD ECM. You NEED to change the lift pump. I did it in thirty minutes in my driveway. Pump cost 185 at NAPA. You can do it yourself easily. If you have any ?'s PM me.

Eric

 

[bboxall]

I changed the lift pump last night, didn't help at all. Going for the throttle position sensor tomorrow.

 

[bboxall]

I changed the APPS (throttle position sensor) tonight and reset the calibration (turn key on, don't start, slowly push accelerator to floor and slowly back up)



Didn't help at all. Still have a noticeable hesitation/ stumble at 1700-1900 rpm. If it was a gasoline engine I would say that one of the spark plugs had a cracked ceramic insulator or a partially bad plug wire.

 

[PC12Driver]

I may be going through the same thing as you are. Not really missing, but a slight fluttering hesitation/surge under light throttle from 1600-2000 ish rpm.



I found corrosion in the plug between my Comp MAP output and the truck's harness. I didn't clean it out very well (remove, insert, remove, insert, etc x10) and the surging went away. That was about two weeks ago and now the surge is back. I have some new plug ends that I'm gonna put on this weekend, so I'll let you know how it turns out.



Not counting a bad VP44 (which would probably have other symptoms too, but maybe not), there's really only a couple of things that could effect the fueling amount on these trucks. The APPS, MAP sensor, and the IAT sensor (and of course all their connections). In my case, the ECM was reading an intermittant low signal from the MAP due to the corrosion (no code since it didn't have an open circuit and the voltages were still within the range). And if the ECM doesn't see boost, it won't give (as much) fuel. Any noise in the MAP signal will result in changes in fueling, similar to twitching the throttle.



Check your connectors (MAP and IAT); hopefully you'll get lucky.

 

[DAWG-1]

Connections

Use Dielectric grease at all the connections. You can also get some electrical contact cleaner and use that first and then put the dielectric grease in the connections.

 

[lfuchs]

Its Going To Be The Injector Pump. My Dads 02 6 Speed Did The Same Thing. It Started Doing It With 75000 Miles On It By 80000 Miles At 1700- 1900 Rpm It Fall On Its Face. We Took In Under Warranty And Dodge Replaced The Lift Pump . 5 Miles Later It Did The Same Thing . We Took It Back To Dodge And Raised Hell. :-{} They Admitted That It Was Going To Need Vp44. It Had A Timing Code In Pump Itself. Ti Took A Week To Get One In . After That It Was Fine.

 

[boydo]

Consider having your injectors pop tested at an injection shop, an injector that weeps or dosen't pulse well will cause the truck to hestitate under certain conditions. I had a stumble simular to yours and I had 3 less than exceptable injectors that weeped and spayed like showerheads not a fine pulsed spay.

 

[PC12Driver]

Well, mine just threw a 237 code (MAP sensor). That's after 6-8 weeks of feeling the surging (which was particularly bad today). So, I guess I'm on the right track for plug corrosion (in my case anyway). I'll find out tonight when I switch the plugs.

 

[Greenleaf]

There will not alway be an active code. A stored code can be logged in a matter of a second or two. Stored codes are retrieved differently than active codes. Stumbling will not always be logged as an active code.



I have had stumbling. Sometimes it a cam sensor and sometimes an injection pump. I'd rather not list the entire troubleshooting procedure as it's printed in the manual. It is extensive. It will first tell you to check for active codes, then stored codes. This will prompt you what chart to follow to perform the troubleshooting.



Scott



BTW I have nine ISB engines here at the school.

 

[bboxall]

I disconnected every connection under the hood, sprayed each with contact cleaner and then dielectric grease. Didn't find any problem connections. I also removed and cleaned all ground connections under the hood. I also ordered a MAP sensor and IAT sensor today. Both will be here Monday - I'll post the results.

 

[bboxall]

Consider having your injectors pop tested at an injection shop, an injector that weeps or dosen't pulse well will cause the truck to hestitate under certain conditions. I had a stumble simular to yours and I had 3 less than exceptable injectors that weeped and spayed like showerheads not a fine pulsed spay.

Well, you were right! One poorly performing injector and another going sour. I decided to replace all 6 - after all if two are bad how far can the others be from going bad?



Truck runs like a swiss watch now.

 

[litespeed]

Use Dielectric grease at all the connections. You can also get some electrical contact cleaner and use that first and then put the dielectric grease in the connections.

To include the connections at the firewall and frame!!



This is a good idea and will prevent future electric headaches and mysteries... .



Any good automotive store carries this grease... CRC makes a small can that can last years if you are liberal.



Good post "Dawg-1"!!!!! Often over looked... ...



AJ

 

[PC12Driver]

Bboxall, just out of curiosity, how many miles do you have on your truck?

 

[HookMeUp]

Must be what I am experiencing also. I took it to the dealer last week and they said nothing is wrong with it. When the stumbling ocurrs the fuel pressure is around 9 PSI and the tach is between 1700-2000 rpm. No codes set. Good thing is the dealer didn't charge me anything.

 

[SKneeland]

mines doing allmost the same thing

mid throttle stumble , notice in 5 & 6

goes away if i turn off the comp

stronger with more defueling (lower sublevels), allmost non-existant on 5x5



going to clean and regrease the electrical connections today hopefully



dirty MAP connection would make sense with the symptoms(stronger with higher defueling-waiting to see boost before fueling)

 

[HookMeUp]

I have notice that mine only does it when warm. When the engine is cold it runs great, which leads me to believe that the IAT sensor may be bad. Does this make any sense?

 

[RAJohnson]

bboxall how many miles when you noticed this problem. Just wondering when it will happen to mine