Dodge Cummins Diesel Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
22 Posts
Discussion Starter #1
I have put in a couple of 3k and 4k kits in 97 and 98 12valve's now, and both have worked great. But what I have noticed with both kits is that when you free rev the trucks they don't rev up smoothly, they seem to miss a bit, or cough. The faster you rev it the worse it is, if you ease into it it isn't as bad. Just wondering what causes this or is something wrong with the install, if not what causes this and can it be fixed?
Thanks in advance
GG
 

·
Registered
Joined
·
384 Posts
sorry to hijack but i have my timing at 16.5 and im installing 4k gsk should my timing be higher?
 

·
Registered
Joined
·
22 Posts
Discussion Starter #4
06smoker thanks for the relpy but I am not talking in the higher rpm range but still down low, like between 1000-2000rpm. Any other thoughts, the one truck is set at 16.5 on the timing and it does it as well.
thanks
 

·
Registered
Joined
·
89 Posts
yes mine did the same thing, the faster you accelerate the worst spittin and sputering got, advance your timing more. and my overflow valve had a little bit to do with it but not much
 

·
Avatarless
Joined
·
4,002 Posts
so your saying that with the stock governor springs you had no sputtering and once you put in the 4gsk it began to sputter?
 

·
Registered
Joined
·
22 Posts
Discussion Starter #7
Yes with the stock springs nice smooth even rev-up, with the 3k or 4k the sputering started. The trucks work great under load or driving, no issues there. All of the shims are removed, and even played with adjusting the gov springs tighter and looser but same results each time.
 

·
Tech Specialist
Joined
·
2,034 Posts
What's the fuel pressure at?
Are the automatics or manuals?

My 4ks really take off after 1200rpm but other than that its smooth.
 

·
Avatarless
Joined
·
4,002 Posts
Yes with the stock springs nice smooth even rev-up, with the 3k or 4k the sputering started. The trucks work great under load or driving, no issues there. All of the shims are removed, and even played with adjusting the gov springs tighter and looser but same results each time.
thats really weird that governor springs would cause you to pop like that, ever more so that its happened multiple times. Like stated above, you need to know fuel pressure to diagnose.
 

·
Avatarless
Joined
·
4,002 Posts
at idle you need to be around ~20psi, but you also need to check it under load if they are dropping below 10-12psi then you have issues.
 

·
Registered
Joined
·
92 Posts
Sounds like you need to advance your timing to me. Mine was the same way popped when revved. Changed my timing and it's nice and smooth now.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #13
So are you saying at 18deg like your sig says that your popping went away, and you had it (popping) at say 16deg?
 

·
Registered
Joined
·
182 Posts
I had the same problem. 21.5 degrees of timing and good fuel pressure (22 psi at idle, 35-40 psi at rpm, 20-30 psi under load depending on load). Overflow valve helped some along with tuning but came back with bigger turbo. It revs nice and smooth under load/in gear not sure what the problem is but truck drives fine.
 

·
Registered
Joined
·
451 Posts
Mine pops also and my fuel pressure is at 25psi at idle but it doesn't go up to 32psi when you rev it to 2500 like it's supposed to
 

·
Registered
Joined
·
2,065 Posts
Yes with the stock springs nice smooth even rev-up, with the 3k or 4k the sputering started. The trucks work great under load or driving, no issues there. All of the shims are removed, and even played with adjusting the gov springs tighter and looser but same results each time.
Sounds like your timing slipped.

On edit, I see thats been covered, but like others said 17-18* is perfect.
 

·
Registered
Joined
·
22 Posts
Discussion Starter #17
One truck is a 98 with stock timing, never been adjusted, so bumping it up will help? The other is set at 16.5 but I will double check that it has not slipped.
 
1 - 17 of 17 Posts
Top