Turbo in 1st Gear?

[Roadglider09]

Question regarding my 98 Dynasty w/ 8.3 Cummins and Alison 6 speed. Should I have turbo in 1st gear? In 1st, it's a real dog and my rpm's won't go over about 1500. My turbo gauge also sits at 0. Once it shifts into 2nd, the turbo kicks in and the coach takes off. I don't recall the coach doing this before, but I haven't been able to drive it for about a year and maybe I just don't remember.

[DSDP_Don]

You said it's been sitting for a year....you may have some other small issues, like old fuel, dirty fuel filters and air cleaner problems.

[havasu]

Sully2 wrote:
If the engine runs...the turbo spins.

Wow that was useful! Not!

A spinning turbo does not generate boost if the wastegate is open!

To answer the OP, the electronic ISC (2001) does restrict boost in first gear to prevent transmission damage.

It should however generate sufficient power to be able to get the wheels rolling before it shifts into second at which point you will have full boost available.

I am not aware of any fixes for this on the general market. I guess that the liability of a twisted/broken driveshaft would prevent most from wanting to market such a device.

[Roadglider09]

Kerrie-Roo wrote:
Has anyone heard of a resolution to this problem? I'm having the same concern on a 2006 HR Endeavor with the 400hp cummins
Tnx
As an added thought : mine also sat for a few months. Something sticking??

I have not found a resolution yet, but I have noticed that it doesn't do it when the engine is cold. Only after it warms up. When it's cold, plenty of go in 1st gear.

[Kerrie-Roo]

Has anyone heard of a resolution to this problem? I'm having the same concern on a 2006 HR Endeavor with the 400hp cummins
Tnx
As an added thought : mine also sat for a few months. Something sticking??

[BigRabbitMan]

If you can "just barely pull away" you have a problem. You need to see a qualified mechanic.

[Sully2]

If the engine runs...the turbo spins.

[Ivylog]

With a 1998 ISC is it a electronic one or the old mechanical injection pump?
How much boost are you getting in the other gears? What is the max that you've seen? It's not the waste gate as it opens when you have too much boost. I know in my 96 FL70 with a maunual tranny it's hard to see much boost in the lower gears as you are not putting enough work on the engine for it to think it needs any boost which is a function for RPMs. The higher the RPMs the more boost it will make if the throttle is all the way down. You can have high RPMs and 0 boost if you are barely on the throttle.
If it's a mechanical pump I'd check for a air leak on the line going to the back of the pump.
If it's an electroinic system, I'd have the codes read to see if the computer knows what's wrong.

*Having thought about this some more, if the the torque converter is locking up (should be unlocked) in 1st (and 2nd) this could explain your problem. My Aladin system tells me things like this so about the only way to check is to have someone with a computer hook up while you drive it. This also assumes it's an electronic ISC.

[Roadglider09]

One reason I think it's a problem is that when I'm towing our motorcycle trailer and pulling away from a stop sign or light, the coach barely moves. It just crawls until I can build enough speed to get to 2nd gear, then the turbo will kick in. Since my trailer, loaded, only weighs 5k pounds and my coach is rated for 10k, I should have no problem pulling it. Indeed, I took it to South Dakota 2 years ago and had no problem pulling away from a stop.
But why would the turbo work in every other gear but 1st?

[Rvndave]

It is not uncommon in pick up trucks, to reduce power to save the automatic transmission.

[AprilWhine]

The engine control unit dials down the torque in 1st gear to prevent twisting the drive shaft. Our diesel SUV does the same thing by locking out 1st gear in the automatic. Sport mode or a real hard pull will allow a 1st gear start, but limits the power until the shift to second.

You know, it is a feature, not a bug..

[McObra]

Turbo chargers operate any time the engine is running. If you aren't getting
boost it may be a mechanical problem with the turbo, the wastegate, ducting or any of several other problems. It should be checked.

[hershey]

I'm pretty sure that the turbo is running in all gears, perhaps there is a computer gate valve that keeps the boost from engaging in low gear?????
My 5.9 acts the same way, I've never noticed the boost in low gear, I'll have to look into that.