Engine/Transmission (1998.5 - 2002) ISB and timing advance

[Cummins Cowboy]

I have had a few observations since I have had my new truck. My old truck was a '93. I have noticed right away that my new truck seems to have less idle torque, when you let the clutch out taking off it seems to lug the engine more, a couple of times i have even killed it going up a steep hill, the first gen would never do that. I have also noticed since it has gotten colder than when I start the engine, The engine sounds like it is just hammering and is very loud, It also seems to almost stall when I go to take off quickly after starting. This all seems to be more evident when the engine is very cold. My question is, is this caused by excessive timing advance?? If so since the ISB has the ability to alter timing advance, why isn't the timing retarded more at lower rpm' to help the engine run better in all situations, seems it would also make the engine run quieter at idle speed??

 

[pcarlson]

cummins cowboy,



My understanding is the injection pump timing is set by an offset key. You can change it to advance the timing, otherwise I don't beleive the ECM changes much of the timing. It gets retarded for emmisions standards throughout the years. Advancing the timing should make it louder. My . 02.

 

[Steve St.Laurent]

The ECM does adjust the timing during cold starts which is why the ISB sounds so different when cold. The reason the timing is set where it is is because of emissions plain and simple. Our engines would run better with more advance but they would also create more emissions. The PE EZ Box, PE Comp Box, VA Box, and the Diablo power puck all advance the timing.

 

[LSMITH]

I believe what cummins cowboy is getting at is that the first gen has a LOAD more torque at idle than the 24V. The timing being advanced on the 24V will cause or at least contribute to this. Retarding the timing at idle would increase torque considerably. If you have never driven a 5 speed first gen the torque at idle will blow your mind. I drove a friends 90 model with less than 1000 miles on it and HAD to have one after the drive. Took me a while LOL.



The timing in our engines varies greatly depending on lots of different factors, with emissions being the largest factor. The first gen timing is mechanical, and is solely based on RPM.

 

[Diesel Freak]

Originally posted by pcarlson

cummins cowboy,



My understanding is the injection pump timing is set by an offset key. You can change it to advance the timing, otherwise I don't beleive the ECM changes much of the timing. It gets retarded for emmisions standards throughout the years. Advancing the timing should make it louder. My . 02.

Do not change the offset key!



The Timing on the ISB is not static. It changes with engine RPM, Intake air Temperature, engine load... etc. etc.

 

[jwilliams3]

Diesel Freak is right.

Do not change that key, it is specific to your fuel pump and is designated by a 2 digit number.



The fuel pump key is sort of like installing shims to align something perfectly.



--Justin