dbrannon79
I'm getting there!
Hello all, I have recently been comparing my truck to others who run a 6.5 with a similar stock setup and noticed that my truck seemed to be lacking power. I had noticed from the beginning that it doesn't have the power to break the tires loose on dry pavement much less barley able to do it in wet conditions. At first I really didn't think much about it since I know it's a heavy really long wheel base crew cab 1 ton pickup, plus I have 265-75 tires on it. But being as it is, even with having 4.10 gears with the 4L80E trans, I've had several friends tell me that it should have more power than it does unless the motor is just worn out (low compression) or having some kind of fueling or timing issue. This got me thinking about the age, mileage, and how it runs (smooth vs rough, missing ect.. ) even with 280k miles on the clock. Currently it has no miss and never skips a beat, idles smooth as if nothing is wrong, so I started doing a lot of reading on forums looking to see if there were some simple things I could check for or try in the hopes that the motor is not worn out. I don't have access to a diesel compression tester so checking the compression is out if the question until I can get my hands on one. while reading, I ran across several threads talking about the "optical bump" that from what I understand is advancing the timing slightly (compensating for minor timing chain wear) and changing the "pre-fueling" time for the injector pump. each thread I read had various results with some even reporting 20+ hp increase running like a scalded ape! so I decided to try it, thinking "what have I got to loose".
before I did the bump I connected GMTDscan and took a snapshot of the PCM readings, also did one after. doing the bump, I moved the optical sensor adjustment in the direction of the passenger side fender guesstimating 1mm (marked it's position before hand) and slapped everything back together. As for my results, I haven't really taken it out on the open road yet but just a quick trip through town I noticed a smoother idle (thought it was smooth before) and seemed to have slightly better pickup response from a traffic light (couldn't go too fast, 30mph limit in town). The engine didn't seem any louder than before, it may have been slightly quieter! anyway I have attached the before and the after PCM snapshots for the you guys to have a look through to see if readings look good or can be better. After my drive through town noticing the slight differences, I'm thinking that the timing may have or is still slightly retarded and I simply brought it closer to where it should be.
on a side note, I have not even attempted to try the TDC relearn. Frankly I'm scared to do it thinking it will make things worse!
let me know your opinions and suggestions, any help is greatly appreciated
before I did the bump I connected GMTDscan and took a snapshot of the PCM readings, also did one after. doing the bump, I moved the optical sensor adjustment in the direction of the passenger side fender guesstimating 1mm (marked it's position before hand) and slapped everything back together. As for my results, I haven't really taken it out on the open road yet but just a quick trip through town I noticed a smoother idle (thought it was smooth before) and seemed to have slightly better pickup response from a traffic light (couldn't go too fast, 30mph limit in town). The engine didn't seem any louder than before, it may have been slightly quieter! anyway I have attached the before and the after PCM snapshots for the you guys to have a look through to see if readings look good or can be better. After my drive through town noticing the slight differences, I'm thinking that the timing may have or is still slightly retarded and I simply brought it closer to where it should be.
on a side note, I have not even attempted to try the TDC relearn. Frankly I'm scared to do it thinking it will make things worse!
let me know your opinions and suggestions, any help is greatly appreciated