• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Lugging vs Boost issues

Flyboy207

Flyboy207

New Member
Messages
29
Reaction score
1
Location
CA
Hey all, I've gone and bought a replacement for my LBZ because the trans was giving me issues and computers aren't my thing...

So I bought a 12 valve.
I've been getting used to the learning curve of the 5 speed manual plus a low redline, and I had a question. In third gear, (which seems to sometimes be too high to shift out of second, and yet only tall enough to get to 35) I will get on it when I first shift to third and it sort of hesitates to boost up until after the RPMs climb past a certain point. :???:

So my question basically is do I have fueling or turbo issues, or am I just lugging the thing? Admittedly I am used to the VGT on the LBZ.
If I have an issue is there a correction for the engine, or do I just need to wind it out farther?

Am I just being a :dr: ?
Thanks for the help.
 
I don't have a Cummins but imagine you need to hold it a bit longer and can't dally on the shift. Shift it out of 2nd as high as it takes you to get established in bottom of 3rd where it feels like it pulls. And its going to feel a little gutless until turbo re-spools. But 3rd isn't so high as 4th and 5th so it should increase rpm slowly. Just be patient. If it can't accelerate try a higher shift out of 2nd (and quicker shift).

Try to roll into fuel with a nice steady increase in pedal and don't just dragster floor it in low gears (1st and 2nd). Trying to accelerate a load is not like racing at least to me its more an anticipation of shift and smooth loading up. Wait til established in 3rd to pin the pedal again I usually mash it floor smoothly and pretty quick but its not a stomp to floor. Slapping the fuel to it might bog it down some in the bottom of 3rd. Anytime you overfuel a diesel for the air (carburetor can be same) it can bog so you have to be established in 3rd pretty quick sometimes. Don't be scared to floor it but if the gear is too tall for the fuel and load its just too tall.

The shifting takes practice and depends on the truck. I can pretty quick pull out of 2nd gear and clutch into 3rd not coming off completely on fuel and roll back into fuel pedal in 3rd decent fast. Its usually only a problem going uphill with heavy load. But 4th and 5th at least for me can be a lack of power for the higher gears and have had to climb hills in 3rd.
 
Sounds normal to me.

Alot of people don't even use first, and start in second because first to too "low" of a gear, and 3rd is alot taller / longer, so I could see where you think it may be Lugging or "Lacking"

Also, don't forget with a manual, every time you shift, you gotta re-spool the turbo, unlike an Auto, where it stays Spooled while it's shifting.

...you can Mod your injection pump to give you up to another 100hp over stock, for free, just by turning some screws and bolts. ;)
 
It seems that all the nv4500 transmissions you need to go a little higher in rpms on the second gear due to the third gear being a lot lower my 6.2 if shifting at 2600 rpm will drop to about 1800-1900 rpms, if i'm pulling Ill go to 2800rpms to get the truck to shift better.
 
I was more considering when towing earlier. It seems to me if you are unloaded or lightly loaded and you launch in 1st and wind it up then tach up 2nd too the gears are so low (vs resistance) you don't really build any heat for making boost. Then 3rd feels gutless at first compared to torque you just felt from the lower gears until boost builds. I use 1st when I can't launch from 2nd from idle no extra fuel (when loaded or decent uphill launch).
 
Don't forget the Aneroid, smoke puff limiter, that delays fuel until there is boost. Boost takes time to come on and is RPM dependent. Keeping the smoke down limits fuel that limits boost at low RPM to a point - you can flood and cool the engine exhaust with lots of black smoke but that is a different story.

MT's are "slow to shift" over an auto. The 6 speed is even slower, but, gives you some close gears for just this reason. I have to double clutch to shift faster after winding a gear out.
 
Man you guys are awesome, I appreciate the help and the detailed replies
 
You must log in or register to reply here.
Back
Top