Bogging/limited power until 30mph???

[Regulator Red]

Hey peeps. Need some ideas here. I've had my truck a few months now and have noticed that there is very little acceleration from a stop until I get up to around 30mph, then it seems to take off and rev up fine. I have taken off the throttle body and completely cleaned it. I have also replaced fuel filter and performed a couple fuel services. My gas mileage improved, but it is still really sluggish from stop. There are a couple of factors I am also considering...... It is a lwb 3500 with 305 tires in the rear. Does anyone know if the 4L80 has a granny gear from factory? It almost acts like I have No first gear because it doesn't shift until around 45 mph. Could the bigger tires cause this? I'm confused and could use some advice. Anyone had this experience? Would clogged spider injectors cause this????

Love life. Live love.

 

[great white]

So, I'll assume it's OBDII since you seem to be talking about a vortec and assume 454 since you're saying 4l80E and it's a 3500.

Pull the OBD codes first and see what's lurking in there....

 

[Regulator Red]

2000 model. 5.7L. No codes present

Love life. Live love.

 

[magimerlin]

Long shot but..... There are two VSS(vehicle speed sensor) on the 4L80 in the 90's not sure if still uses two in the 2000 years or not. Unplug them and see if either are wet with transmission fluid. If either are then replace the wet/bad one.. Also check the big plug near the rear of the trans as well for the same issue.

What about the mass air flow sensor? That would kill your lower end acceleration.. May just need to be cleaned.

 

[Regulator Red]

Thanks, I will check.

Love life. Live love.

 

[grampadirt]

Sounds like it's not downshifting into 1st. when stopped & starting in 2nd when taking off.Try shifting manually from 1st. to see what it does.

 

[Regulator Red]

That is exactly what it feels like. My wife took it to work (she loves driving it. Even over her awd Honda pilot), so I'll check it later. Thanks

Love life. Live love.

 

[grampadirt]

Where I used to work we had a few Chevy trucks with transmissions that if you put the gearshift in ''2'' it would start off in second,not first.Read somewhere that's for starting off if you're on snow,ice,etc.....basically slippery conditions,to reduce the chance of spinning the tires.If done on dry ground it would do what you describe.

 

[96Z71ECSB]

Yup. Mine does the 2nd gear slow takeoff when you select "2".
As suggested, try manually selecting first gear and see if the truck moves.
If it doesn't move, I would say the trans is done.