Engine/Transmission (1998.5 - 2002) Some what weird engine problem?

[jeff77indy]

On my '01 it sometimes feels like the brakes are being bumped at medium to low speeds, usually when going up a grade. Don't notice it at highway speeds. Also the weather and fuel tank level does not seem to affect it.

The injector pump was replaced about a year ago. I did not have the same symptoms when it went.

Fuel pressure is 20 PSI at idle and 18-19 PSI at WOT. The truck had the same symptoms before the Glacier LP install.

Jeff

 

[DMcPherson]

first thing first, cycle the key 3 times and see if you get any codes. start there

 

[jeff77indy]

I'll check for codes again.

I checked before but none were showing.

Jeff

 

[jeff77indy]

Well I checked for codes and it is not throwing any.

Update on symptoms are does it mostly when cold, running at 1800 RPM. fuel tank level has no affect, fuel pressure stays at 18-20 PSI.

Jeff

 

[GCULP]

try this, with the engine off, pump the accelerator pedal about 20 times all the way to the floor, then go drive it. Mine has the same sympton and I replaced the APPS (accelerator pedal position sensor thingy) and it went away. The APPS is like a dimmer switch with metal contacts that build up carbon, pumping the pedal will sometimes clear it off, but it's only a short time fix.

 

[PC12Driver]

Maybe a flat spot developing on the APPS? Slowly depress the throttle while in neutral and see if you get a stumble around 1800 rpm. I had that around 80k miles. Felt like a tugging on the truck. No codes set.

 

[Cummins724]

If I am understanding you correctly. It pulses like it isn't getting fuel correctly right? Are you sure it isn't a fuel filter? Possibly bad fuel? Maybe try a fuel additive to clean injectors... ... or antigel. I've been seeing some weird stuff with gelled fuel lately around here.

 

[Cummins724]

Maybe a flat spot developing on the APPS? Slowly depress the throttle while in neutral and see if you get a stumble around 1800 rpm. I had that around 80k miles. Felt like a tugging on the truck. No codes set.

That is very possible, but my truck threw a 1693 right away when my apps started to go. I'd clear it & it would just come back right away. I just changed mine last week. I ran it with the bad apps for a month before the po121 code showed up for apps.

 

[jeff77indy]

GCULP; Thanks for the response I'll try your t/s technique in the morning and see how it goes.



PC12Driver: That is exactly how it feels, thanks for the response.



Cummins 724; I've been been around diesel engines all my life, tractors, heavy equipment and have driven 1st Gen Dodge Cummins for years, I believe I know what a diesel engine that is not getting fuel feels like and this is nothing like that, it is a tug. Yes I have changed filters, and use Diesel Service at least every other tank of fuel. Fuel is purchased at the same station every time.

As far as codes this truck did not throw any when the VP was going not until it was gone.

Thanks all for the responses and the help.

Jeff

 

[MCummings]

My truck does this when the MAP is acting funky.



My MAP sensor is within specs, so it doesn't throw a code, but it tells the ECM that I have 3psi, then 15psi, 3, 15, 3, 15, 3, 15. Kinda feels like a brake drum that is out of round.



Merrick

 

[Cummins724]

Cummins 724; I've been been around diesel engines all my life, tractors, heavy equipment and have driven 1st Gen Dodge Cummins for years, I believe I know what a diesel engine that is not getting fuel feels like and this is nothing like that, it is a tug. Yes I have changed filters, and use Diesel Service at least every other tank of fuel. Fuel is purchased at the same station every time.

As far as codes this truck did not throw any when the VP was going not until it was gone.

Thanks all for the responses and the help.

Jeff

Sorry! I was only trying to help... ... sometimes the basics get overlooked.

 

[jeff77indy]

Well I cycled the pedal to the floor 20 times with the key switch off this morning. The wife drives this truck so when she got to work she called me at work to tell me that the truck ran fine. I'll see when she gets home tonight if the symptoms returned or not.

Since it looks like this is the culprit. Where is the best palce to buy a new APPS, the dealer? Any tricks with changing it out?

Thanks for all the help.

Cummins724 sorry I came accross the way I did.

Jeff

 

[Cummins724]

Well I cycled the pedal to the floor 20 times with the key switch off this morning. The wife drives this truck so when she got to work she called me at work to tell me that the truck ran fine. I'll see when she gets home tonight if the symptoms returned or not.

Since it looks like this is the culprit. Where is the best palce to buy a new APPS, the dealer? Any tricks with changing it out?

Thanks for all the help.

Cummins724 sorry I came accross the way I did.

Jeff

I would read issue 54 of TDR mag [page 40] & it says that the APPS can sometimes be fixed. You drill a 1/8" hole in it in a certain spot & shoot some tuner control cleaner & lubricant... . then rotate the APPS control briskly through its range. Reconnect APPS & battery terminals. This sometimes works, but may not..... its still worth a try for $395. Hope this helps.

 

[PC12Driver]

Where is the best palce to buy a new APPS, the dealer? Any tricks with changing it out?

I bought mine from Hoesli Diesel. Good price, good service.



No tricks to the install, just a quick swap. And since you have a manual truck, slowly depressing the pedal to the floor and releasing it with the key on (before starting the engine) will calibrate it. Autos may have to go through the reclocking method to get the APPS output voltage to match the PCM.

 

[jeff77indy]

Well the wife drove home with no symptoms so I guess the APPS is the culprit.



Cummins724 thanks for pointing out the write up in TDR, I'll pickup some tuner cleaner at Radio Shack on my way home tommorrow and see how it works.



PC12Driver I'll check the link for a new APPS for later as the cleaner fix will most likly be temporary.



Thanks.

Jeff