Attention: TDR Forum Junkies 
Apparently it's been so gradual I haven't noticed.
I have a great Cummins mechanic, he is very experienced and I greatly respect his opinion. I bought my '98 12V almost 4 years ago, about a year later I had the valves adjusted, the pump readjusted, and the timing set. Afterwards it ran great!
30k miles later, I take the truck back in and have a 4kGSK installed. When I picked it up, he tells me that he noticed on the test drive the engine was sluggish and down on power. He suspected the timing may be off. I reminded him that he set it 3 years ago, so feels there may be some other problem. I'm taking it back next week so he can investigate the problem. I realize that the timing may have slipped, so hopefully that's still it.
BUT, in the two days since, I've noticed that it runs slightly different than before the 4kGSK install. The idle speed was down to 600 RPM with the trans in gear and the AC on (I don't think he adjusted it), of course if I downshift it will rev to 3000+ (as high as I'll take my stock valve springs for now), but mainly it seems to hit a power wall at about 2200 rpm that I don't think was there before. Other than that, it runs the same as it did before. At 2200 rpm, it just seems like the engine won't accelerate like it used to.
I have changed the fuel filter and reset the idle speed, but it's still the same. I do believe he will find the problem and fix the truck, but I'm still wondering what may have changed. Any thoughts?
I have a great Cummins mechanic, he is very experienced and I greatly respect his opinion. I bought my '98 12V almost 4 years ago, about a year later I had the valves adjusted, the pump readjusted, and the timing set. Afterwards it ran great!
30k miles later, I take the truck back in and have a 4kGSK installed. When I picked it up, he tells me that he noticed on the test drive the engine was sluggish and down on power. He suspected the timing may be off. I reminded him that he set it 3 years ago, so feels there may be some other problem. I'm taking it back next week so he can investigate the problem. I realize that the timing may have slipped, so hopefully that's still it.
BUT, in the two days since, I've noticed that it runs slightly different than before the 4kGSK install. The idle speed was down to 600 RPM with the trans in gear and the AC on (I don't think he adjusted it), of course if I downshift it will rev to 3000+ (as high as I'll take my stock valve springs for now), but mainly it seems to hit a power wall at about 2200 rpm that I don't think was there before. Other than that, it runs the same as it did before. At 2200 rpm, it just seems like the engine won't accelerate like it used to.
I have changed the fuel filter and reset the idle speed, but it's still the same. I do believe he will find the problem and fix the truck, but I'm still wondering what may have changed. Any thoughts?
