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

[bboxall]

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.

Well, that was short lived. After a two days it is stumbling/hesitating again but not as sharply for the first few days. Now it is running poorly. New VP44 will be installed on Friday.

 

[Diesel Freak]

I have had this issue from day one!!!!



It is more pronounced when temps drop under 45F.



I blocked off the air to the CAC with a piece of cardboard, and the shudder disapeared.



WARNING: if you do this, keep an eye on coolant temps when idling in stop and go traffic.

 

[bboxall]

Well the new injectors didn't seem to fix it after all. It steadily got worse and it got its new VP44 today. It now runs like it did when it was new.



I have learned not to start replacing sensors until they actually generate an error code.



I have also learned NEVER EVER run the VP44 out of fuel - it'll kill it EVERY TIME.

To make sure this doesn't happen, NEVER RELY ON THE FUEL GAUGE - use the odometer and fill up according to mileage.



An education can sometimes be expensive... $805 in sensors it didn't need, $1500 in new injectors and diagnostic work to track down the hesitation, $2335 for a new VP44 installed. All work except for the sensors was done by a Cummins authorized shop.

 

[GCULP]

man, mine is doing exactly the same thing, only thing different is Dodge Dealer replaced my VP44 and it didn't fix the problem.

 

[JKinney]

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.

I cant give the proper procedure, but from what Ive read here that is not the correct way to adjust the apps.

 

[RAJohnson]

Yep your right JKinney here it is.



RESETTING THE APPS SENSOR.

(ACCELERATOR PEDAL POSITION SENSOR)

2ND GENERATION 24 VALVE TRUCKS ONLY.



LIST OF TOOLS NEEDED



DIGITAL VOLT METER

# 20 TORQUE BIT SOCKET

# 1 PHILLIPS

# 10 MM SOCKET



Proper service and repair procedures are vital to ensure personal safety of those performing the repairs. Standard safety procedures and precautions should be followed at all times to eliminate the personal injury or improper service, which could damage the vehicle or compromise its safety.

Although this material has been prepared with the intent to provide reliable information, no liability is assumed in reliance of this material.



It has come to my attention that a lot of people think by disconnecting & re-connecting the batteries and stepping on the throttle it is going to reset the apps, no, that is not correct. It is impossible to adjust your apps if you do not know where it is supposed to be set at. That is why you need the voltmeter.



This is the procedure I use to re-set the apps.



With the key on, engine off you need to probe the apps wire to see where your voltage is currently set at.

The best location to probe the wire is on the PCM (power control module) which is located off the passenger side of the firewall.



• You want the C1 connector, this is the connector closest to the engine,

• You want the orange wire with the dark blue tracer which is pin # 23

• Voltage should read somewhere around 0. 5 volts,

• At this point the voltage reading does not matter, it just has to be accurately written down for later reference.



*** TURN THE IGNITION OFF ON THE TRUCK ***



• The apps sensor is located slightly above and a little to the left of the injection pump.



• Remove the black plastic cover that is located by your injection pump.



The two screws that are holding it are plastic, do not put any downward pressure on them or you will never get them off.



• Un do the 6 - 10 mm headed bolts that hold the bracketry in place.

(DO NOT REMOVE THE CABLES)



You will notice the apps is on the back of the bracketry that you just removed, it is held in place by 2 - 20 bit screws. These screws have a little bit of locktite on them so make sure you have a good socket and gently give a little tap with a hammer before attempting to loosen. Be very careful these screws strip very easily and you only get one shot at them.



• On the apps you will find a white tag that gives you the information on what the apps adjustment should be.



• After loosening the screws you can rotate the apps both clockwise and counter clockwise to get the adjustment you need.



• The reading you took at the beginning of the process on pin # 23 should match the white tag on your apps, if not adjust accordingly.

 

[KDoerr]

Good Day To all Well I had the problem and I still have it. I did it a I replaced the injectors and the pumps and adjusted the apps and I still have the problem I even changed the Clutch and it is still there. so keep me posted on what you all find out.

Thanks Keith

 

[PC12Driver]

It sounds like that procedure is only going to adjust the voltage output of the APPS at zero throttle, since you're only re-clocking the potentiometer in the APPS. How is this supposed to help surging?

 

[PC12Driver]

Good Day To all Well I had the problem and I still have it. I did it a I replaced the injectors and the pumps and adjusted the apps and I still have the problem I even changed the Clutch and it is still there. so keep me posted on what you all find out.

Thanks Keith

Do you have the surge with the cruise set?

 

[GCULP]

Do you have the surge with the cruise set?

I don't know about him, but mine is smooth when on Cruise Control, that was one of the first things tried. Next?

 

[PC12Driver]

I don't know about him, but mine is smooth when on Cruise Control, that was one of the first things tried. Next?

On the electronic cruise control trucks (i. e. no vacuum servo pushing the pedal for you) the APPS is taken out of the loop when the cruise is set and your foot is off the pedal.



If the surging stops when you set the cruise, I'd lean toward the APPS as being the source of the surge.

 

[GCULP]

If the surging stops when you set the cruise, I'd lean toward the APPS as being the source of the surge.

I was going that direction too untill I took it to the dealer and he put the computer on it and I watched the voltages as I pressed the pedal up and down several times, and held it static at all different points through the pedal throw both running and not running without any anomolies (sp?)

 

[KDoerr]

PC12Driver Do you have the surge with the cruise set?







Sorry it took so long to get back. No I don't have cruise I have a hand throttle and it will surge when I set that. With the hand throttle the petle get press down as you pull the hand throttle so I have no idea on what could be going on. Any more suggestions?



As Again sorry it took so long to get back I was busy with work.



Thanks Keith

 

[bboxall]

On my '01 24valve both the cruise and the pedal actuate the APPS. The APPS then tells the computer how much throttle is being requested and the computer puts the fuel into the engine. But yes, mine hesitated on cruise just as it did on the pedal.

 

[KDoerr]

So What is Going on with these trucks?



It seem that I'm not the only one who has this problem.

 

[PC12Driver]

On my '01 24valve both the cruise and the pedal actuate the APPS.

Your pedal moves with cruise on? I thought all of the '01 manuals used e-cruise (internal to the ecm - does not use the apps).

So What is Going on with these trucks?

I'd say it's age. Mine was corrosion on a MAP plug and a worn APPS. Mix that in with a worn-in VP44, agressive injectors, and a timing box, and the effect is amplified. Since I've replaced the worn parts (and a VP44 that coded out on me shortly after), I'd swear that my truck is smoother than it was when I drove it home from the dealership.



After seeing what's inside an APPS, I'm surprised that they last as long as they do. It's easy to see that a little bit of brush dust could cause some noise that would cause surge. Or how easy it would be to wear some dead spots in a particular throttle setting.

 

[KDoerr]

PC12Driver

I'd say it's age. Mine was corrosion on a MAP plug and a worn APPS. Mix that in with a worn-in VP44, agressive injectors, and a timing box, and the effect is amplified. Since I've replaced the worn parts (and a VP44 that coded out on me shortly after), I'd swear that my truck is smoother than it was when I drove it home from the dealership.









With My truck I had the motor rebuild after 530,000 Km because one of the injectors had failed and it was doing it back then and now I have the stock Injectors and only the Edge chip (the small one) and I still have the problem. And as far as I know the injector pump, MAP, APPS is all new but I think I will check for corrosion in the MAP plug.

Thanks

PC12 I will try that.



Keith